@article { ISI:000234202200037, title = {3-Aminopropyltriethoxysilyl functionalized Na-Al-MCM-41 solid base catalyst for selective preparation of 2-phenylpropionitrile from phenylacetonitrile}, journal = {Applied Catalysis A-General}, volume = {292}, year = {2005}, month = {SEP}, pages = {344-353}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Various solid base catalysts have been prepared by ion exchange of zeolites and Na-Al-MCM-41 and by organosilane grafting over mesoporous materials. Base catalysts thus synthesized were studied in the selective monomethylation of phenylacetonitrile (PAN) to 2-phenylpropionitrile (2-PPN) using dimethylcarbonate (DMC) as an alkylating agent in a Parr autoclave at a temperature ranging between 443 and 473 K and at autogenously developed pressure. NH2-Na-Al-MCM-41 (30) showed a high activity, and the optimum loading of 3-aminopropyltriethoxysilyl (3-APTES) was found to be 1.35 mmol g(-1), being consistent with the structural characterization. Co-condensation of 3-APTES, tetraethylorthosilicate (TEOS) and sodiumaluminate in the presence of surfactant provides a material with uniformly distributed basic sites responsible for high activity in the selective monomethylation of phenylacetonitrile. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {2-phenylpropionitrile, base catalysis, dimethylcarbonate, monomethylation, NH2-Na-Al-MCM-41, phenylacetonitrile}, issn = {0926-860X}, doi = {10.1016/j.apcata.2005.06.013}, author = {Venkatesan, C. and Chidambaram, M. and Singh, A. P.} } @article { ISI:000231401000008, title = {Influence of silica source in the catalytic activity and heterogenity of mesoporous vanadosilicates}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {239}, number = {1-2}, year = {2005}, month = {SEP}, pages = {57-63}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Vanadium-substituted ordered mesoporous silicates (V-OMS) were synthesized hydrothermally using two common silica sources, viz. fumed silica and tetraethyl orthosilicate, and their surface properties and catalytic activities were evaluated in the liquid phase oxidation of 1-napthol using aqueous H2O2 as an oxidant. The catalysts were characterized by XRD, N-2, adsorption-desorption, DRUV-vis and TPR to evaluate the mesostructural ordering and the local environment of vanadium in the MCM-41 matrix. Characterization data of the fresh calcined catalysts reveal a more ordered hexagonal structure for the V-MCM-41 catalyst prepared by using tetraethyl orthosilicate as the silica source while spent catalyst showed that the material is less stable than the V-MCM-41 catalyst prepared by using fumed silica as the silica source. Further, the observed differences in the selectivity behavior of extracted and calcined forms of both vanadium catalysts shows that the treatment conditions had a decisive role in the formation of extra framework metal species and further in the mesoscopic structural ordering. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {1-napthol, MCM-41, Mesoporous, Oxidation, Vanadium}, issn = {1381-1169}, doi = {10.1016/j.molcata.2005.05.029}, author = {Shylesh, S. and Mirajkar, Subhash P. and Singh, A. P.} } @article { ISI:000232712200011, title = {Synthesis, characterization and catalytic activity of Mn(III)- and Co(II)-salen complexes immobilized mesoporous alumina}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {241}, number = {1-2}, year = {2005}, month = {NOV}, pages = {79-87}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Mn(III) and Co(II)-schiff base complexes were immobilized over mesoporous alumina through the reaction of mesoporous alumina functionalized 3-aminopropyl triethoxy silane (3-APTES) and salicylic aldehyde via schiff base condensation. The surface properties of the functionalized catalysts were analyzed by a series of characterization techniques like elemental analysis, PXRD, FTIR, N(2) adsorption-desorption, TG-DTG, DR UV-vis, XPS, etc. PXRD and adsorption-desorption analysis shows that the mesostructure of alumina remains intact after various modifications, while spectral technique show the successful anchoring of the neat complexes inside the porous alumina support. The catalytic activity of the functionalized metal-salen complexes examined in the liquid phase oxidation of styrene and cyclohexene shows that the functionalized salen complexes are more active and selective than the corresponding neat metal complexes. Further, the catalyst (Mn-S-NH(2)-MA) was recycled three times in the oxidation of styrene and no major change in the conversion and selectivity is observed, which shows that the immobilized metal-salen complexes are stable under the present reaction conditions. (c) 2005 Elsevier B.V. All rights reserved.

}, keywords = {Immobilization, Mesoporous alumina, Oxidation, Schiff base complexes}, issn = {1381-1169}, doi = {10.1016/j.molcata.2005.07.005}, author = {Chaube, V. D. and Shylesh, S. and Singh, A. P.} } @article { ISI:000240279200047, title = {Assembly of hydrothermally stable ethane-bridged periodic mesoporous organosilicas with spherical and wormlike structures}, journal = {Microporous and Mesoporous Materials}, volume = {94}, number = {1-3}, year = {2006}, month = {SEP}, pages = {364-370}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Hydrothermally stable periodic mesoporous organosilicas with spherical as well as wormlike frame structures were synthesised by two different synthesis routes using the silsesquioxane precursor, 1,2-bis (triethoxy silyl) ethane (BTEE) and surfactant octadecyl trimethyl ammonium (ODTA), under basic conditions. The materials were characterized by PXRD, SEM, TEM, N-2 adsorption-desorption, FT-IR, Si-29 MAS NMR, C-13 CP MAS NMR and TG-DTA techniques. Characterization techniques revealed that the morphology of the hybrid material prepared from pure silsesquioxane precursor resulted in spherical particles while a combination of tetra ethyl orthosilicate and 1,2-bis (triethoxy silyl) ethane (90:10 ratio) resulted in materials having wormlike structures. Hydrothermal stability of the hybrid material was evaluated by refluxing the sample under boiling water for various time periods and was compared with that of a periodic mesoporous silica material, Si-MCM-41. Results showed that the hybrid material is stable up to 100 h in boiling water, with the existence of d(100) peak, while the mesopore structure of Si-MCM-41 get destroyed even after a 12 h reflux time. The improved hydrothermal stability of the hybrid material is related to the more hydrophobic environment induced inside the pore channels, due to the presence of integrating ethane groups in the wall channels. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {hybrid mesoporous materials, Hydrothermal stability, spherical particles, wormlike structures}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.04.012}, author = {Shylesh, S. and Jha, Ratnesh Kumar and Singh, A. P.} } @article { ISI:000239671800023, title = {Cobalt-containing hexagonal mesoporous molecular sieves (Co-HMS): Synthesis, characterization and catalytic activity in the oxidation reaction of ethylbenzene}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {255}, number = {1-2}, year = {2006}, month = {AUG}, pages = {123-130}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Cobalt-containing hexagonal mesoporous materials (Co-HMS and Co/HMS) with different cobalt content were synthesized for the first time by direct hydrothermal and post-synthesis (grafting) method. The materials were characterized in detail by X-ray diffraction, BET surface area, N-2 sorption isotherms, SEM, TEM, UV-vis and XPS techniques. Powder X-ray diffraction pattern, N2 adsorption-desorption analysis and TEM analysis show the presence of hexagonal mesoporous structure, having Type W isotherms and reveals the typical wormhole-like morphology. Spectroscopic techniques like UV-vis and XPS reveal cobalt in +2 oxidation state and tetrahedrally coordinated. Liquid phase oxidation of ethylbenzene using TBHP (70 wt\%) as an oxidant shows that the catalysts are highly active, under solvent free conditions as well as under lower cobalt concentrations. Leaching studies performed by hot filtration experiments show that the cobalt catalysts prepared by hydrothermal methods are stable, while the grafted catalysts show the leaching of cobalt under the reaction conditions. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Co-HMS, ethylbenzene, HMS, hydrothermal, Oxidation}, issn = {1381-1169}, doi = {10.1016/j.molcata.2006.03.072}, author = {Bhoware, Shrikant S. and Shylesh, S. and Kamble, K. R. and Singh, A. P.} } @article { ISI:000239869200010, title = {Organosilanesulfonic acid-functionalized Zr-TMS catalysts: synthesis, characterization and catalytic applications in condensation reactions}, journal = {Applied Catalysis A-General}, volume = {310}, year = {2006}, month = {AUG}, pages = {79-90}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Organosilanesulfonic acid (-Si-R3S-R4SO3H, OSA)-functionalized mesoporous Zr-TMS (Zr-TMS-Si-R3S-R4SO3H, Zr-TMS-OSA) was synthesized either by post-synthetic modification of Zr-TMS (zirconia-based transition metal oxide mesoporous molecular sieves) with 3-mercaptopropyltrimethoxysilane (3-MPTS) and further with 1,4-butanesultone (1,4-BS) or by in situ one-pot synthesis procedure. A number of physico-chemical characterization techniques have been used to show that the organosilanesulfonic acid groups were anchored on to the walls of Zr-TMS. MCM-41-Si-R3S-R4SO3H-20 (MCM-41-OSA-20) was also prepared by post-synthesis procedure for comparison. Physico-chemical properties of in situ made A-Zr-OSA-20, Zr-TMS-SO3H-20 and MCM-41-OSA-20 were compared with Zr-TMS-OSA catalysts. The catalytic activity of the materials was tested in liquid phase condensation of aniline with p-formaldehyde to 4,4{\textquoteright}-diaminodiphenylmethane (4,4{\textquoteright}-DADPM). Results showed that Zr-TMS-OSA catalysts were more active than Zr-TMS-SO3H-20, MCM-41-OSA-20 and A-Zr-OSA-20 and more selective than Zr-TMS-SO3H-20 and A-Zr-OSA-20 catalysts. (C) 2006 Elsevier B.V. All rights reserved.

}, keywords = {Acid catalyst, condensation of aniline, mesoporous ZrO2, organic functionalization, organosilanesulfonic acid}, issn = {0926-860X}, doi = {10.1016/j.apcata.2006.05.024}, author = {Chidambaram, M. and Venkatesan, C. and Singh, A. P.} } @article { ISI:000241306300020, title = {Oxidation of ethyl benzene and diphenyl methane over ordered mesoporous M-MCM-41 (M = Ti, V, Cr): synthesis, characterization and structure-activity correlations}, journal = {Microporous and Mesoporous Materials}, volume = {95}, number = {1-3}, year = {2006}, month = {OCT}, pages = {154-163}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Transition metals (M = Ti, V, Cr) were incorporated into the MCM-41 framework by surfactant-assisted direct hydrothermal (DHT) methods and were characterized in detail by XRD, N-2 adsorption-desorption, TG-DTG/DTA, SEM/TEM, DR UV-Vis, XPS and EPR. The structural regularity as well as the textural properties of the M-MCM-41 materials was confirmed by XRD, TEM and adsorption-desorption techniques. Nature of metal species and the percentage of framework as well as extra framework metal sites in the MCM-41 matrix are discussed in detail by various spectroscopic techniques. The catalytic activity as well as the selectivity of the M-MCM-41 catalysts were explored in the one-step liquid-phase oxidation reaction of ethyl benzene and diphenyl methane. Reaction data showed that the oxidation activity is more when H2O2 was used an oxidant, acetonitrile as solvent and V-MCM-41 as catalyst. However, the selectivity towards the desired keto derivatives (ethyl benzene to acetophenone and diphenyl methane to benzophenone) follows the order, Ti-MCM-41 \> V-MCM-41 \> Cr-MCM-41. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {diphenyl methane, Ethyl benzene, MCM-41, Oxidation}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.04.018}, author = {Jha, Ratnesh Kumar and Shylesh, S. and Bhoware, Shrikant S. and Singh, A. P.} } @article { ISI:000240279200017, title = {Vanadium-containing ethane-silica hybrid periodic mesoporous organosilicas: synthesis, structural characterization and catalytic applications}, journal = {Microporous and Mesoporous Materials}, volume = {94}, number = {1-3}, year = {2006}, month = {SEP}, pages = {127-138}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Vanadium-containing ethane-silica hybrid mesoporous silsesquioxane materials (V-HMM) with uniform hexagonal arrangement were prepared using C-18-, C-16- and C-14-alkyl trimethyl ammonium (ATMA) surfactants under basic conditions. The materials were characterized by PXRD, N-2 adsorption-desorption, UV-Visible spectroscopy, Raman, Si-29, C-13 and V-51 solid-state MAS NMR, TEM and SEM techniques. The characterization techniques revealed that the structural ordering, morphology as well as the percentage of metal incorporation depends strongly on the hydrophobic chain length of the surfactant. PXRD, electron microscopy and N-2 adsorptiondesorption analysis confirmed that the original hexagonal structure of the material is maintained after vanadium substitution. UV-Visible, V-51 NMR and Raman analysis certified that vanadium exists in a highly dispersed state and had tetrahedral coordination with the support surface. Liquid-phase epoxidation reaction of styrene using aqueous H2O2 and TBHP as oxidants, showed that the hybrid materials were highly active and more stable than conventional vanadosilicates. The high catalytic activity and improved epoxide selectivity of the V-HMM samples is related to the more hydrophobic environment inside the pore channels than the silica channels in V-MCM-41. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {epoxidation, organo vanadosilicates, styrene, V-HMM, V-MCM-41}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.03.027}, author = {Shylesh, S. and Singh, A. P.} } @article { ISI:000245961800008, title = {Benzylsulfonic acid functionalized mesoporous Zr-TMS catalysts: an efficient and recyclable catalyst for the preparation of coumarin derivatives by pechmann condensation reaction}, journal = {Catalysis Communications}, volume = {8}, number = {5}, year = {2007}, month = {MAY}, pages = {777-783}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Benzylsulfonic acid functionalized mesoporous Zr-TMS (Zr-TMS-BSA, Zr-TMS, zirconia based transition metal oxide mesoporous molecular sieves) catalyst is used as an alternative to conventional acid catalysts in the von Pechmann condensation of aromatic alcohols with ethyl acetoacetate leading to the formation of coumarin derivatives in solvent free condition at 150 degrees C. Three types of coumarins, 7-hydroxy-4-methylcoumarin (beta-methylumbelliferone), 7-methoxy-4-methylcoumarin (Methyl-4-methylumbelliferyl ether) and 7,8-benzo-4-methylcoumarin derivatives have been prepared using resorcinol, 3-methoxyphenol and 1-naphthol, respectively. The catalytic activity and the recycle studies of the catalyst in all the three reactions proved the superior performance of the catalyst. Further the products were confirmed by GC, elemental analysis, melting point and NMR techniques. Finally, the probable mechanism for Pechmarm condensation using Zr-TMS-BSA catalyst has been reported. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {benzylsulfonic acid, Pechmann condensation and coumarins, Zr-TMS-BSA catalysts}, issn = {1566-7367}, doi = {10.1016/j.catcom.2006.08.039}, author = {Selvakumar, S. and Chidambaram, M. and Singh, A. P.} } @article {52}, title = {Characterization and catalytic activity of cobalt containing MCM-41 prepared by direct hydrothermal, grafting and immobilization methods}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {266}, number = {1-2}, year = {2007}, month = {APR}, pages = {118-130}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

{Cobalt containing hexagonal mesoporous molecular sieves (MCM-41) were prepared by different methods viz., direct hydrothermal synthesis, grafting and immobilization. The calcined material was characterized by various spectroscopic tools such as powder X-ray diffraction (XRD), N-2 adsorption-desorption isotherms, Fourier transformed infra-red (Fr-IR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance UV-vis and X-ray photoelectron spectroscopy (XPS). The XRD patterns show the highly intense (100) reflection peak in the range 2-3 degrees (2 theta angle), characteristic of mesoporous material. Higher order reflection peaks suggest highly ordered mesoporous structure. N2 adsorption-desorption isotherms are of type IV according to IUPAC classification and the steep rise in the isotherms in the narrow range 3.5-4.5 of relative pressure (P/P-0) is due to the condensation of N-2 gas molecules in the pores (characteristic of mesoporous structure). In FT-IR increase in the intensity of band at 960 cm(-1) with the increase of the cobalt content in Co-MCM-41 samples indicate the incorporation of cobalt ions in the framework of MCM-41. SEM and TEM reveal spherical morphology for the cobalt substituted MCM-41. UV-vis spectra demonstrate the characteristic features of framework and extraframework cobalt in MCM-41. Cobalt is in +2 oxidation state as evidenced from UV-vis and XPS. The catalysts were tested for the side chain oxidation of ethylbenzene using 70 wt.\% tert-butyl hydrogen peroxide as an oxidant with and without the use of solvent. Solvents have effect in the catalytic activity and selectivity. In the absence of solvent, substituted cobalt [

}, keywords = {2-butanol, cyclohexanone, Mesoporous molecular sieves, MPV reduction}, issn = {1381-1169}, doi = { 10.1016/j.molcata.2006.09.031}, author = {Bhoware, Shrikant S. and Singh, A. P.} } @article { ISI:000244144700016, title = {Chromium-containing small pore mesoporous silicas: synthesis, characterization and catalytic behavior in the liquid phase oxidation of cyclohexane}, journal = {Applied Catalysis A-General}, volume = {318}, year = {2007}, month = {FEB}, pages = {128-136}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Organic-inorganic hybrid mesoporous silica materials containing chromium and various organo trialkoxysilanes (chloropropyl, vinyl, methyl) were prepared by the co-condensation method, in the presence of cetyl trimethyl ammonium surfactants. The hybrid material, containing chromium, retains one X-ray diffractogram (XRD) peak up to a molar ratio of 1: 1 between tetra ethyl orthosilicate (TEOS) and organosilane in the synthesis gel. Small pore mesoporous chromium-silica samples can be prepared from the large pore hybrid mesoporous chromium samples by calcination. By this method, the pore size of the material can be tailored into the supermicroporous region, without changing the chain length of the surfactant used in the assembly process, as judged from the XRD and N-2 sorption isotherms. The shrinkage in pore size is dependent on the nature and percentage of the organic pendant groups, such that the chloro propyl and vinyl pendant mesoporous material show more pore size shrinkage than the smaller methyl pendant units. Because of the tailorable pore size and with better textural characteristics, the chromium samples show better catalytic activity in the aerial oxidation reaction of cyclohexane than the conventional chromium-containing mesoporous material, like Cr-MCM-41, under a solvent free system. Among the porous chromium catalysts, the samples prepared using chloro propyl silane show higher cyclohexane conversion and cyclohexanone selectivity and behave as a true heterogeneous catalyst. (c) 2006 Elsevier B.V. All rights reserved.

}, keywords = {chromium, Cyclohexane, Oxidation, small pore silicas}, issn = {0926-860X}, doi = {10.1016/j.apcata.2006.10.046}, author = {Shylesh, S. and Samuel, Prinson P. and Singh, A. P.} } @conference { ISI:000291657600254, title = {Ethane bridged hybrid mesoporous silsesquioxanes with sulfonic acid functionalities: synthesis, characterization and catalytic applications}, booktitle = {From Zeolites to Porous Mof Materials: the 40th Anniversary of International Zeolite Conference, Proceedings of the 15th International Zeolite Conference}, series = {Studies in Surface Science and Catalysis}, volume = {170}, year = {2007}, note = {15th International Zeolite Conference, Beijing, PEOPLES R CHINA, AUG 12-17, 2007}, month = {AUG}, pages = {1899-1904}, publisher = {Elsevier Science BV}, organization = {Elsevier Science BV}, address = {Sara Burgerhartstraat 25, Po Box 211, 1000 AE Amsterdam, Netherlands}, abstract = {

Periodic mesoporous organosilicas having -CH(2)-CH(2)- groups in the framewall positions and sulfonic acid groups in the pore channels were prepared using 1,2-bis(triethoxysilyl) ethane, 3-mercaptopropyltriethoxysilane and cetyltrimethylammonium surfactant, under basic conditions, by a one-pot synthesis method. XRD, N(2) sorption isotherm and TEM analysis revealed that the mesoporous structural ordering is retained after the functionalization of organic groups while solid-state NMR techniques like (13)C CP MAS NMR and (29)Si MAS NMR show the presence of sulfonic acid groups and the stability of the mesoporous framework with integrated ethane moieties as bridging groups. The hybrid material was more active, selective and stable than the conventional sulfonic acid containing mesoporous catalysts in the Claisen-Schmidt condensation of acetophenone with benzaldehyde to form chalcone.

}, isbn = {978-0-444-53068-4}, issn = {0167-2991}, author = {Shylesh, S. and Samuel, Prinson P. and Parischa, Renu and Singh, A. P.}, editor = {Xu, R and Gao, Z. and Chen, J and Yan, W} } @article { ISI:000244106200013, title = {One step synthesis of chromium-containing periodic mesoporous organosilicas and their catalytic activity in the oxidation of cyclohexane}, journal = {Microporous and Mesoporous Materials}, volume = {99}, number = {3}, year = {2007}, month = {FEB}, pages = {334-344}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Chromium-containing ethane-bridged hybrid mesoporous materials (Cr-PMO) with uniform hexagonal arrangement were synthesized by two different synthesis routes using 1,2-bis(triethoxysilyl)ethane (BTEE) and tetraethyl orthosilicate (TEOS) as silica sources and alkyltrimethyl ammonium salts (ATMA) as surfactants. Powder X-ray diffraction, TEM, N-2 adsorption-desorption, FT-IR, in situ FT-Raman, UV-ViS, XPS, Si-29 MAS NMR and C-13 CP MAS NMR were used to probe the mesoporous structure and the nature of chromium sites in the hybrid catalyst matrix. PXRD, TEM and N-2 adsorption-desorption analysis showed that the original hexagonal structure of the materials is maintained after chromium substitution, while FT-Raman, UV-Vis and XPS analysis showed that chromium atoms exist in a highly dispersed state. The catalytic performance of the chromium-containing hybrid samples was tested in the liquid-phase oxidation of cyclohexane with aqueous hydrogen peroxide (H2O2) and non-aqueous tert-butylhydroperoxide (TBHP) as oxidants. The hybrid materials exhibited better catalytic activities and were more stable than the conventional Cr-MCM-41 catalyst. The higher catalytic activity of the new chromium-containing molecular sieves is attributed to the improved hydrophobicity of the materials and to the complementary structural features that facilitates the accessibility of cyclohexane to the active framework chromium sites. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {Cr-MCM-41, Cr-PMO, Cyclohexane, hybrid mesoporous materials, Oxidation}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.09.029}, author = {Shylesh, S. and Srilakshmi, Ch. and Singh, A. P. and Anderson, B. G.} } @article { ISI:000249091400025, title = {Sulfonic acid functionalized mesoporous silicas and organosilicas: synthesis, characterization and catalytic applications}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {274}, number = {1-2}, year = {2007}, month = {SEP}, pages = {153-158}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Ethane bridged mesoporous organosilicas and MCM-41 having sulfonic acid groups in the pore channels were prepared by co-condensation method as well as grafting method, using 3-mercaptopropyltriethoxysilane (3-MPTS) as the sulfur precursor. TEM and N-2 sorption isotherm analysis revealed that the mesoporous structural ordering is retained after the functionalization and modifications of organic groups while FT-IR, Raman, XPS and solid-state C-13 CP MAS NMR shows the presence of sulfonic acid groups and the stability of the mesoporous framework. The catalytic activity of the developed materials was evaluated in the liquid phase Claisen-Schmidt condensation reaction of acetophenone with benzaldehyde, to probe the effect of mesoporous support surfaces as well as the role of preparation methods. Results showed that sulfonic acid functionalized ethane-silica samples were more active, selective and stable than the conventional sulfonic acid containing mesoporous catalysts. (c) 2007 Elsevier B.V. All rights reserved.

}, keywords = {condensation, ethane-silica, heterogeneity, sulfonic acids}, issn = {1381-1169}, doi = {10.1016/j.molcata.2007.04.040}, author = {Shylesh, S. and Samuel, Prinson P. and Srilakshmi, Ch. and Parischa, Renu and Singh, A. P.} } @article { ISI:000244798300032, title = {Synthesis of hydrothermally stable aluminium-containing ethane-silica hybrid mesoporous materials using different aluminium sources}, journal = {Microporous and Mesoporous Materials}, volume = {100}, number = {1-3}, year = {2007}, month = {MAR}, pages = {250-258}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Aluminium-containing ethane-silica hybrid mesoporous materials having ethane groups in the frame wall positions are synthesized using aluminium isopropoxide as well as aluminium nitrate as the aluminium sources. The materials were characterized in detail using powder XRD, N-2 adsorption-desorption, SEM, TEM, TG-DTG, TPD, Si-29, C-13 and Al-27 MAS NMR techniques. Characterization techniques revealed that aluminium isopropoxide was the appropriate source for the synthesis of organo aluminosilicas on considering the structural ordering, acidity as well as the percentage of aluminium incorporation into the ethane bridge. Al-27 MAS NMR displays aluminium as tetrahedrally coordinated in both the aluminium-containing organosilicas. Unlike the conventional EtOH-HCl template extraction process, in the present studies, we had used EtOH-NH4OH as the surfactant-extracting medium and chemical analysis results suggest that using this procedure the extent of dealumination can be greatly reduced. XRD and nitrogen physisorption studies further proved that the materials are hydrothermally stable, that the ordered pore channels retains its structure even after 150 h reflux in boiling water, while the conventional Al-MCM-41 catalyst collapsed its mesostructure after 50 h reflux in water. The improved hydrothermal stability of the hybrid materials, even in presence of sodium ions, is attributed to the thick pore walls as well as due to the presence of hydrophobic bridging ethane groups in the wall positions. (c) 2006 Elsevier Inc. All rights reserved.

}, keywords = {Al-HMM, Al-MCM-4l, hybrid materials, Hydrothermal stability}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2006.11.010}, author = {Shylesh, S. and Samuel, Prinson P. and Singh, A. P.} } @article { ISI:000252529400004, title = {Bridging the gap between micropores and mesopores by the controlled transformation of bifunctional periodic mesoporous silicas}, journal = {Microporous and Mesoporous Materials}, volume = {108}, number = {1-3}, year = {2008}, month = {FEB}, pages = {29-40}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Novel bifunctional periodic mesoporous silicas having high content of organic groups in the pore channels and chromium in the frame wall has been synthesized by direct co-condensation method, using organo trialkoxysilanes (chloro propyl, vinyl, methyl), chromium nitrate and tetraethyl orthosilicate, in presence of cetyltrimethyl ammonium surfactants. The obtained materials show one main peak in the XRD patterns up to a molar ratio of 1: 1 between TEOS and organosilane in the synthesis gel and N-2 adsorption-desorption analysis shows that the mesopore structure remains intact after the surfactant removal process. Among the organosilanes, chloro propyl and vinyl pendant chromium samples shows a shift in the main peak to higher 2-theta values with a corresponding decrease in pore volume and pore diameter, with the percentage of organosilane functionalization. Small-pore silicas and chromium silicas can be prepared from the large pore mesoporous MCM-41, by effectively removing the organic groups by calcination. By this method, the pore size of the material can be tailored into the super-microporous region, without changing the chain length of the surfactant used in the assembly process. The shrinkage in pore size is dependent on the nature and percentage of the organic pendant groups that the chloro propyl and vinyl pendant mesoporous materials show the maximum pore size shrinkage than the small chain length methyl units. Because of the tailorable pore size and with better textural characteristics, chromium-silica materials find applications in the field of shape selective heterogeneous catalysis, as demonstrated in the oxidation reaction of cyclohexane, than the conventional metal-containing mesoporous materials. (c) 2007 Elsevier Inc. All rights reserved.

}, keywords = {bifunctional silicas, chromium, Cyclohexane, MCM-41, Oxidation}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2007.03.039}, author = {Shylesh, S. and Srilakshini, Ch. and Singh, A. P. and Anderson, B. G.} } @article { ISI:000261329400003, title = {Periodic mesoporous silicas and organosilicas: an overview towards catalysis}, journal = {Catalysis Surveys from Asia}, volume = {12}, number = {4}, year = {2008}, month = {DEC}, pages = {266-282}, publisher = {SPRINGER/PLENUM PUBLISHERS}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Micelle-templated mesoporous and organic-inorganic hybrid mesoporous materials are important in many fields of material research, especially for hosting catalysts in confined space. Among this class, the recent discovery of periodic mesoporous organosilicas (PMOs) represent an exciting new group of organic-inorganic nanocomposites targeted for a broad range of applications ranging from catalysis to microelectronics. Compared to the earlier generation of organic-inorganic hybrid mesoporous samples, obtained by the cocondensation reaction or by the grafting reaction, PMOs represent the right combination of organic and inorganic groups in the frame wall positions. This article reviews the current state of art in organic-inorganic hybrid mesoporous material research with special emphasis over periodic mesoporous organosilica materials having various redox centers (Ti, V, Cr) suitable for oxidation reactions as well as acidic sites (Al, -SO(3)H) for the organic transformation of bulky molecules.

}, keywords = {Acid catalysis, epoxidation, Mesoporous organosilicas, Organic-inorganic hybrid materials}, issn = {1571-1013}, doi = {10.1007/s10563-008-9056-2}, author = {Shylesh, S. and Samuel, Prinson P. and Sisodiya, Sheetal and Singh, A. P.} } @article { ISI:000263509700017, title = {Benzoylation of anisole over silicotungstic acid modified mesoporous alumina}, journal = {Catalysis Letters}, volume = {128}, number = {3-4}, year = {2009}, month = {MAR}, pages = {363-372}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Mesoporous alumina (MA) molecular sieves were synthesized by using aluminum sec-butoxide as Al precursor and lauric acid as the structure directing agent. The synthesized MA was functionalized with silicotungstic acid (STA) via wet impregnation method and characterized by various physico-chemical techniques. The XRD patterns of a series of HPA functionalized MA are showing the ordered structures. N(2) sorption analysis shows type IV isotherm. NH(3)-TPD measurements revealed an increase in number of acid sites with an increase in loading of STA over MA. At the same time decrease in the acidity was observed with the increase in calcination temperature of the supported materials. Functionalization of STA were also carried out over different alumina supports such as catapol-B (CB) and alumina synthesized without surfactant (ASW) and their activities were evaluated by carrying out liquid phase Friedel-Craft acylation (FC) reaction of anisole with p-toluoyl chloride in a batch reactor at 120 degrees C. Recycling was performed in the FC reaction using 30 wt\% STA-MA two times and no major deactivation of the catalyst was observed.

}, keywords = {Friedel-Craft acylation, Mesoporous alumina, Silicotungstic acid}, issn = {1011-372X}, doi = {10.1007/s10562-008-9755-3}, author = {Selvakumar, S. and Singh, A. P.} } @article { ISI:000271443200015, title = {Catalytic activity of cobalt containing MCM-41 and HMS in liquid phase oxidation of diphenylmethane}, journal = {Catalysis Letters}, volume = {133}, number = {1-2}, year = {2009}, month = {NOV}, pages = {106-111}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Cobalt containing MCM-41 and HMS were synthesized by direct hydrothermal (DHT) and post synthesis methods (grafting and immobilization). The catalytic activity of these materials was investigated in the liquid phase oxidation of diphenylmethane at 80 A degrees C with TBHP (70 wt\%) as oxidant. Comparative study of cobalt containing MCM-41 and HMS was carried out to reveal the catalytic performance of framework, extraframework and immobilized cobalt species. The role of the solvent in the performance of catalyst was examined with different polar and non polar solvents. Oxidation of diphenylmethane in solvent free media (under similar reaction conditions) shows formation of hydroxy derivatives of benzophenone in addition to main product (benzophenone). Hundred percent selectivity to benzophenone was obtained when the reaction was carried out in solvent.

}, keywords = {diphenylmethane, HMS, Immobilization, MCM-41, XRD}, issn = {1011-372X}, doi = {10.1007/s10562-009-0162-1}, author = {Bhoware, Shrikant S. and Kamble, K. R. and Singh, A. P.} } @article { ISI:000270665200029, title = {Catalytic aerobic oxidation of cyclohexane and ethyl benzene over chromium-containing mesoporous organosilicas}, journal = {Catalysis Letters}, volume = {132}, number = {3-4}, year = {2009}, month = {OCT}, pages = {492-499}, publisher = {SPRINGER}, address = {233 SPRING ST, NEW YORK, NY 10013 USA}, abstract = {

Chromium-containing ethane-bridged hybrid periodic mesoporous organosilicas (Cr-PMO) were synthesized using 1,2-bis(triethoxysilyl) ethane (BTEE) and tetraethyl orthosilicate (TEOS) as silica sources and alkyltrimethyl ammonium salts as surfactants by two different synthesis routes. PXRD and N(2) adsorption-desorption analysis shows that the original structure of the materials is maintained after chromium substitution while spectroscopic study proves the incorporation of chromium in the frame wall positions and show the existence of Cr(2)O(3) species in the mixed silica source (BTEE-TEOS) synthesized chromium samples. The catalytic activity of the newly developed chromium samples was evaluated in the liquid phase oxidation of cyclohexane and ethylbenzene using air as an oxidant. Further, the Cr-PMO samples exhibited better cyclohexane conversion and cyclohexanone selectivity than the conventional Cr-MCM-41 and other metal-containing MCM-41 samples. The exceptional activity of the new chromium-containing molecular sieves is attributed to the hydrophobicity of the materials and to the complementary structural features that facilitates the accessibility of substrate to the active framework chromium sites.

}, keywords = {Cr-MCM-41, Cyclohexane, Ethyl benzene, Organosilicas, Oxidation}, issn = {1011-372X}, doi = {10.1007/s10562-009-0121-x}, author = {Singh, A. P. and Torita, N. and Shylesh, S. and Iwasa, N. and Arai, M.} } @article { ISI:000264437500028, title = {Ru(II)-Chiral (1R,2S)-(+)-cis-1-amino-2-indanol immobilized over SBA-15 for asymmetric transfer hydrogenation reaction of prochiral ketones}, journal = {Catalysis Today}, volume = {141}, number = {1-2}, year = {2009}, note = {18th National Symposium and Indo-US Seminar on Catalysis, Indian Inst Petroleum, Dehradun, INDIA, APR 16-18, 2007}, month = {MAR}, pages = {161-167}, publisher = {Catalysis Soc India; Petrotech Soc; Indo US Sci \& Technol Forum}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Mesoporous SBA-15 (Santa Barbara University at California) has been synthesized and functionalized with (4-chloromethyl)phenyltriethoxysilane, there after the surface silanols groups were passivated by dimethoxydimethylsilane (MeO(2)Me(2)Si) [Bz-SBA-15]. Further (1R,2S)-(+)-cis-1-amino-2-indanol [AIL] has been immobilized over functionalized SBA-15 (BzAIL-SBA-15). The heterogeneous catalysts were synthesized by complexation of BzAIL-SBA-15 by [RuCl(2)(benzene)](2) and [RuCl(2)(p-cymene)](2) in 2-propanol at reflux condition designated as Ru-Bn-BzAIL-SBA-15 (Ru-1) and Ru-Cy-BzAIL-SBA-15 (Ru-2). The synthesized materials have been characterized by small angle X-ray diffraction spectroscopy (SAXS), N(2) adsorption-desorption isotherms, Fourier Transformed-Infra-red (FT-IR) spectroscopy, Transmission Electron Microscopy (TEM), intensively Coupled plasma atomic emission spectroscopy (ICP-AES), Diffuse reflectance UV-vis and (13)C CP MAS NMR analysis. Further the synthesized and characterized materials (Ru-1 and Ru-2) have been successfully applied in the asymmetric transfer hydrogenation (ATH) reaction of simple prochiral ketones, which gave a yield of 56\% and 18\% and enantiomeric excess (ee) values of 62\% and 77\% for Ru-1 and Ru-2, respectively, after 1 h for acetophenone. The reusability studies showed approximately the same enantiomeric excess value at lower conversions. (c) 2008 Elsevier B.V. All rights reserved.

}, keywords = {(1R, 2S)-(+)-Cis-1-amino-2-indanol, Asymmetric transfer hydrogenation, Chiral amino alcohols, Mesoporous molecular sieve, Prochiral ketones, SBA-15}, issn = {0920-5861}, doi = {10.1016/j.cattod.2008.04.003}, author = {Parambadath, Surendran and Singh, A. P.} } @article { ISI:000274058400003, title = {Nature of the acid sites in the metal triflates immobilized in SBA-15 and their role in the friedel-crafts acylation of naphthalene}, journal = {Applied Catalysis A-General}, volume = {372}, number = {2}, year = {2010}, month = {JAN}, pages = {130-137}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

The Zn-triflate molecules loaded (5-30 mol\%) in mesoporous SBA-15 silicate exhibited considerably higher catalytic activity for liquid-phase Friedel-Crafts (FC) acylation of naphthalene with p-toluoyl chloride, as compared to the corresponding triflates of La, Ce and Y. In situ FTIR studies revealed that the triflate molecules occluded in the channels of SBA-15 may cause severe perturbation of surface hydroxyl groups, without undergoing an electronic binding. The metal cations of the triflate molecules, on the other hand, participated in direct bonding of the reactant molecules and also helped in the formation of some Bronsted type surface acid sites. This article discusses the role of the acid sites generated on occlusion of metal triflates in SBA-15, as monitored by using NH(3)-TPD and pyridine-IR spectroscopy, in the Friedel-Crafts acylation of naphthalene. (C) 2009 Elsevier B.V. All rights reserved.

}, keywords = {Acylation, Mesoporous silica, Metal triflate, Naphthalene}, issn = {0926-860X}, doi = {10.1016/j.apcata.2009.10.021}, author = {Selvakumar, S. and Gupta, Narendra M. and Singh, A. P.} } @article { ISI:000273709900033, title = {Vice to virtue: intracellular biogenic nanoparticles for the generation of carbon supported catalysts}, journal = {Journal of Nanoscience and Nanotechnology}, volume = {10}, number = {2}, year = {2010}, month = {FEB}, pages = {905-911}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {25650 NORTH LEWIS WAY, STEVENSON RANCH, CA 91381-1439 USA}, abstract = {

Intracellular biogenic nanoparticles are considered disadvantageous as the separation of the nanoparticles from the biomass becomes intricate. However realizing the importance of carbon supported catalyst for many important organic reactions we envisaged these nanoparticles as a source for carbon supported catalyst. Herein we demonstrate the heat treatment of intracellular biogenic nanoparticles under inert atmosphere as an efficient method for the preparation of carbon supported metal oxide catalysts. Aspergillus ochraceus, a fungus isolated from foundries, on incubation with K(2)TiF(6) led to the synthesis of intracellular titanium oxide nanoparticles. The nanoparticles embedded biomass upon heat treatment at 600 degrees C in a nitrogen environment gave titanium oxide nanoparticles implanted in a carbonaceous matrix. The material thus formed was characterized using FTIR spectroscopy, Raman spectroscopy, HRTEM and X-ray diffraction. Appreciable benzaldehyde selectivity was observed when styrene oxidation was carried out over such immobilized catalysts. The conversion rate was determined to be 76\% and the benzaldehyde selectivity was greater than 80\%.

}, keywords = {Benzaldehyde Selectivity, Biosynthesis, Carbon Supported Titania, Nanoparticles, Styrene Oxidation}, issn = {1533-4880}, doi = {10.1166/jnn.2010.1894}, author = {Vijayakumar, P. S. and Selvakumar, S. and Gholap, Ramkrishna S. and Singh, A. P. and Bhagavatula L. V. Prasad} } @article { ISI:000296674400011, title = {Synthesis and characterization of bifunctional ethenylene bridged mesoporous organoaluminosilicates}, journal = {Nanoscience and Nanotechnology Letters}, volume = {3}, number = {4}, year = {2011}, month = {AUG}, pages = {497-502}, publisher = {AMER SCIENTIFIC PUBLISHERS}, address = {26650 THE OLD RD, STE 208, VALENCIA, CA 91381-0751 USA}, abstract = {

Bifunctional mesoporous organosilicas having -CH=CH- bridges and aluminium in tetrahedral coordination with tailorable pore sizes have been synthesized using a one-step templating method using cationic surfactants of different chain lengths. Unlike the conventional EtOH-HCl template extraction process, EtOH-NH(4)NO(3) was used as the surfactant-extracting medium and chemical analysis results suggest that through this procedure the mesoporous structure can be retained and dealumination can be minimized. The surfactant-extracted mesoporous solids display high surface area, pore volume and the pore size of the material varies in the range 2.6-3.6 nm, with respect to the alkyl chain length of the cationic surfactant. XRD and nitrogen physisorption studies further proved that the organosilicas are hydro thermally stable than the conventional Al-MCM-41 materials and their better stability is attributed to the thick pore walls as well as due to the presence of hydrophobic bridging ethenylene groups in the wall positions. The coupling of Al(4) with -CH=CH- bridges offer new prospects for the application of periodic mesoporous organosilicas in heterogeneous catalysis.

}, keywords = {Aluminium, Cationic Surfactants, Hydrothermal stability, Organosilicas}, issn = {1941-4900}, doi = {10.1166/nnl.2011.1196}, author = {Shylesh, S. and Kapoor, Mahendra P. and Juneja, Lekh R. and Srilakshmi, Ch. and Singh, A. P.} } @article { ISI:000287839600014, title = {Tin incorporated periodic mesoporous organosilicas (Sn-PMOs): synthesis, characterization, and catalytic activity in the epoxidation reaction of olefins}, journal = {Catalysis Communications}, volume = {12}, number = {7}, year = {2011}, month = {MAR}, pages = {629-633}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Tin incorporated mesoporous organosilicas (Sn-PMO) having uniform hexagonal arrangements were prepared using alkyl trimethylammonium bromide surfactants under basic reaction conditions. Characterization techniques revealed that the structural ordering, morphology, and the percentage of tin incorporation depend critically on the hydrophobic chain length of surfactants. The Sn-PMO samples are thermally stable up to 500 degrees C under air atmosphere and were hydrothermally stable up to 100 h in boiling water. The organotinsilicates showed excellent catalytic activity and reusability in the epoxidation of norbornene and ciscyclooctene than an Sn-MCM-41 due to organic groups in the frame wall positions and the better accessibility of reactants to the active sites. (C) 2010 Elsevier B.V. All rights reserved.

}, keywords = {epoxidation, Hydrothermal stability, Mesoporous, Organosilica, Sn-MCM-41, Sn-PMO}, issn = {1566-7367}, doi = {10.1016/j.catcom.2010.11.025}, author = {Sisodiya, Sheetal and Shylesh, S. and Singh, A. P.} } @article { ISI:000311350000024, title = {Binapthyl Schiff base diamine complex covalently bonded to modified SBA-15: synthesis, characterization and catalytic application}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {184-188}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Protected mesoporous SBA-15 phase was synthesized by grafting the complex Chloro (S,S)(-)[N-3-tert-butyl-5-chloromethyl salicylidene]-N{\textquoteright}-[3{\textquoteright},5{\textquoteright}-di tert-butyl salicylidene] 1,1{\textquoteright}-binapthyl-2,2{\textquoteright}-diamine manganese(III) through the reactive 3-aminopropyl trimethoxysilane(3-APTMS) group. The surface properties of the functionalized catalyst were analyzed by a series of characterization techniques like elemental analysis, XRD, N-2 sorption measurement isotherm, FT-IR, XPS, and solid state C-13 NMR. The screening of the catalyst Mn(III)-L-SBA-15 and neat Mn(III)-L complexes was done for the oxidation reaction of thioanisole (methyl phenyl sulfide) using TBHP as an oxidant. Mn(III)-L-SBA-15 catalyst shows higher activities and exhibit enantiomeric excess comparable to homogeneous catalyst. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {-OH protected NH2-SBA-15, Binaphthyl Schiff base ligand, Ordered mesoporous materials, Sulfoxidation, Thioanisole}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.05.024}, author = {Sharma, Priti and Singh, A. P.} } @article { ISI:000308731400012, title = {Mn(III) based binapthyl schiff base complex hetrogenized over organo-modified SBA-15: synthesis, characterization and catalytic application}, journal = {Applied Catalysis A-General}, volume = {439}, year = {2012}, month = {OCT}, pages = {101-110}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A heterogenized organocatalyst was synthesized by the covalent anchoring; of the complex chloro (S,S)(-)[N-3-tert-butyl-5-chloromethyl salicylidene]-N{\textquoteright}-[3{\textquoteright},5{\textquoteright}-di-tert-butyl salicylidene] 1,1{\textquoteright}-binapthyl-2,2{\textquoteright}-diamine manganese(III) over modified mesoporous surface of SBA-15 through the reactive 3-aminopropyl trimethoxysilane (3-APTMS) group. The surface properties of the functionalized catalyst were analyzed by a series of characterization techniques such as elemental analysis, XRD, N-2 sorption measurement isotherm, FT-IR, TGA-DTA, XPS, and solid state C-13 NMR. The XRD and N-2 sorption measurement, UV reflectance and CP MAS NMR spectroscopy (C-13 and Si-29) of the catalyst confirmed the structural integrity of the mesoporous hosts and the spectroscopic characterization technique proved the successful anchoring of the metal complex over the modified mesoporous support. The screening of the catalyst Mn(III)-L-SBA-15 and neat Mn(III)-L complexes was done in the oxidation reaction of thioanisole (methyl phenyl sulfide) by using TBHP as an oxidant. Mn(III)-L-SBA-15 catalyst shows higher activities and turnover number (TON) and exhibit enhanced enantiomeric excess comparable to homogeneous catalyst [Mn(III)-L]. [Mn(III)-L-SBA-15] catalyst was found more active than homogeneous catalyst [Mn(III)-L]; Moreover bulkier alkene like 1,2-dihydronapthalene was also efficiently epoxidised with the synthesized supported catalyst. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {Binaphthyl ligand, Chiral Schiff-base, Immobilization, Post grafting synthesis}, issn = {0926-860X}, doi = {10.1016/j.apcata.2012.06.048}, author = {Sharma, Priti and Lazar, Anish and Singh, A. P.} } @article { ISI:000315614700038, title = {Chiral (VO)-O-IV-Sal-Indanol complex over modified SBA-15: an efficient, reusable enantioselective catalyst for asymmetric sulfoxidation reaction}, journal = {Microporous and Mesoporous Materials}, volume = {170}, year = {2013}, month = {APR}, pages = {331-339}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A reusable, mesoporous, heterogeneous vanadium complex, (VO)-O-IV-Sal-Ind-SBA-15 has been synthesized first time from (1R,2S)-(+)-Cis-1-amino-2-indanol for enantioselective sulfoxidation reaction. The physico-chemical properties of the functionalized catalyst were analyzed by a series of characterization techniques like XRD, N-2 sorption measurement isotherm, TEM, FT-IR, XPS, EPR, DRS UV-Visible, ICP-OES and solid \& liquid state C-13, Si-29 and V-51 NMR spectroscopy. Powder X-ray diffraction patterns, TEM and N-2 physisorption analysis confirmed the retention of mesoporous structure after various modifications. Solid-state NMR (C-13 CP-MAS NMR, Si-29 MAS NMR) and FT-IR analysis certified the integrity of organo-catalyst residing inside the pore channels of the mesoporous support. Further, XPS, EPR, V-51 NMR and DRS UV-Visible analyses help to find out the oxidation state and coordination environment of vanadium in (VO)-O-IV-Sal-Ind-SBA-15. Catalytic evaluation in asymmetric sulfoxidation reaction of sulfides indicated that VOIV-Sal-Ind-SBA-15 exhibited higher catalytic activity, stability, reusability and comparable enantioselectivity than SBA-15, PrNH2-SBA-15, neat (VO)-O-IV-Sal-Indanol complex and without catalyst. The effect of different catalysts, temperature, solvents and substrates on sulfoxidation reaction were examined in order to optimize the conversion and enantioselectivity of thioanisoles to sulfoxides. Crown Copyright (C) 2012 Published by Elsevier Inc. All rights reserved.

}, keywords = {(1R, 2S)-(+)-Cis-1-amino-2-indanol, Asymmetric sulfoxidation, Heterogeneous vanadium complex, Mesoporous, Thioanisole}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2012.12.014}, author = {Lazar, Anish and Sharma, Priti and Singh, A. P.} } @article { ISI:000324656500008, title = {Clay entrapped Cu(OH)(x) as an efficient heterogeneous catalyst for ipso-hydroxylation of arylboronic acids}, journal = {Applied Catalysis A-General}, volume = {466}, year = {2013}, month = {SEP}, pages = {60-67}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A remarkably active, selective and stable montmorilonite-KSF entrapped Cu(OH)(x) catalyst, has been prepared for the ipso-hydroxylation of arylboronic acids under ambient conditions without requirement of any ligand or base. This catalyst shows excellent reusability without leaching and any significant loss in catalytic activity. The catalyst was characterized using, XRD, SEM, TPR, IR, XPS and BET surface area measurement techniques. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {clay, Copper, heterogeneous catalysis, Phenols, Water chemistry}, issn = {0926-860X}, doi = {10.1016/j.apcata.2013.06.051}, author = {Dar, Bashir Ahmad and Bhatti, Prince and Singh, A. P. and Lazar, Anish and Sharma, Parduman R. and Sharma, Meena and Singh, Baldev} } @article { ISI:000325039100047, title = {Ultrasound promoted efficient and green protocol for the expeditious synthesis of 1, 4 disubstituted 1, 2, 3-triazoles using Cu(II) doped clay as catalyst}, journal = {Applied Clay Science}, volume = {80-81}, year = {2013}, month = {AUG}, pages = {351-357}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Cu(II) doped clay catalyst has been prepared by an easy technique from inexpensive starting materials and investigated for the one pot synthesis of 1, 4-disubstituted 1, 2, 3-triazoles via Huisgen [3 + 2] cycloaddition under ultrasonic irradiation at room temperature. The catalyst is highly active, selective, and stable and can be reused several times. The prepared catalyst has been characterized by XRD, BET-SA, H-2-TPR, SEM and XPS techniques. This transformation is fast, efficient and does not require nitrogen atmosphere or anoxic conditions and additive. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Catalyst support, Copper catalyst, Crystallization, selectivity, Sustainability}, issn = {0169-1317}, doi = {10.1016/j.clay.2013.06.030}, author = {Dar, Bashir Ahmad and Bhowmik, Amrita and Sharma, Amit and Sharma, Parduman R. and Lazar, Anish and Singh, A. P. and Sharma, Meena and Singh, Baldev} } @article { ISI:000330822900026, title = {Clay encapsulated Cu(OH)(x) promoted homocoupling of arylboronic acids: an efficient and eco-friendly protocol}, journal = {Applied Catalysis A-General}, volume = {470}, year = {2014}, month = {JAN}, pages = {232-238}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Cu(OH)(x) has been encapsulated over montmorillonite-KSF by simple ologomeric deposition strategy. The resulting catalyst has been employed for selective homocoupling of arylboronic acids under ambient conditions without requirement of any ligand or base. This catalyst is easy to recover and shows excellent reusability without losing its activity. Techniques like XRD, SEM, TPR, IR, BET surface area measurement and XPS were used to characterize the catalyst. The present method promises for the simple and clean homocoupling of arylboronic acids. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {Biaryls, clay, Copper, Heterogenous catalyst, Homocoupling}, issn = {0926-860X}, doi = {10.1016/j.apcata.2013.10.048}, author = {Dar, Bashir Ahmad and Singh, Snehil and Pandey, Nalini and Singh, A. P. and Sharma, Priti and Lazar, Anish and Sharma, Meena and Vishwakarma, Ram A. and Singh, Baldev} } @article { ISI:000345460800049, title = {Covalently anchored 2,4,6-triallyloxy-1,3,5-triazine Pd(II) complex over a modified surface of SBA-15: catalytic application in hydrogenation reaction}, journal = {RSC Advances}, volume = {4}, number = {102}, year = {2014}, month = {OCT}, pages = {58467-58475}, publisher = {ROYAL SOC CHEMISTRY}, type = {Article}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Highly efficient and reusable SBA-15-TAT-Pd(II) has been synthesized by anchoring a 2,4,6-triallyloxy-1,3,5-triazine (TAT) complex over the organo-functionalized surface of SBA-15. The physiochemical properties of the organo-functionalized catalyst were analyzed by elemental analysis, ICP-OES, XRD, N-2 sorption measurement isotherm, TGA \& DTA, solid state C-13, Si-29 NMR spectra, FT-IR, XPS, DRS UV-visible, SEM and TEM. XRD \& N-2 sorption were analyzed to find out the textural properties of the synthesized catalyst and confirm that an ordered mesoporous channel structure was retained even after the multistep synthetic procedures. The electronic environment and oxidation state of Pd in SBA-15-TAT-Pd(II) were monitored by XPS and DRS UV-visible techniques. The catalytic activity of the synthesized catalyst SBA-15-TAT-Pd(II) was screened for hydrogenation reactions and shows higher catalytic activity with good turnover numbers (TON) under optimized experimental conditions with maximum conversion (\> 99\%) and selectivity (100\%). The anchored solid catalyst can be recycled efficiently and reused upto five times without major loss in reactivity.

}, issn = {2046-2069}, doi = {10.1039/c4ra10002f}, author = {Sharma, Priti and Singh, A. P.} } @article { ISI:000340208400025, title = {Phosphine free SBA-15-EDTA-Pd highly active recyclable catalyst: synthesis characterization and application for suzuki and sonogashira reaction}, journal = {Catalysis Science \& Technology}, volume = {4}, number = {9}, year = {2014}, month = {AUG}, pages = {2978-2989}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

Phosphine obstructed highly efficient and reusable SBA-15-EDTA-Pd(11) has been synthesized by anchoring a Pd-EDTA complex over the surface of organo-functionalized SBA-15. The physiochemical properties of the organo-functionalized catalyst were analyzed by elemental analysis, ICP-OES, XRD, N-2 sorption measurement isotherms, TGA and DTA, solid state C-13, Si-29 NMR spectroscopy FT-IR, XPS DRS UV-visible, SEM and TEM. The XRD and N-2 sorption analyses of the synthesized catalyst confirm that the ordered mesoporous channel structure was retained even after the multistep synthetic procedures. The (100), (110) and (200) reflections in SBA-15 provide a good structural stability, an the existence of a long range order and high pore wall thickness. The TGA-DTA results reveal that the thermal stability of the synthesized catalyst SBA-15-EDTA-Pd(11) was maintained at higher temperature. The organic moieties anchored over the surface of the SBA-15 and inside the pore wall were demonstrated by solid state C-13 NMR and FT-IR spectroscopy. Further, solid state Si-29 NMR spectroscopy provides information about the degree of functionalization of the surface silanol groups, of the SBA-15 with organic moieties. The electronic environment and oxidation state of the Pd metal in the SBA-15-EDTA-Pd(11) were monitored by XPS, and DRS UV-visible techniques. Moreover, the morphologies and topographic information of the synthesized catalyst were confirmed by SEM and TEM spectroscopy. The synthesized catalyst SBA-15-EDTA-Pd(11) was screened for the Suzuki and Sonogashira coupling reactions and shows a higher catalytic activity with higher TON (turn over number). The anchored solid catalyst can be recycled efficiently and reused five times, without a major loss in the reactivity.

}, issn = {2044-4753}, doi = {10.1039/c4cy00144c}, author = {Sharma, Priti and Singh, A. P.} } @article { ISI:000333205200038, title = {Synthesis and characterization of 3-[N,N {\textquoteleft}-bis-3-(salicylidenamino)ethyltriamine] Mo(VI)O-2@SBA-15: a highly stable and reusable catalyst for epoxidation and sulfoxidation reactions}, journal = {RSC Advances}, volume = {4}, number = {27}, year = {2014}, month = {MAR}, pages = {14063-14073}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The efficient and reusable oxidation catalyst 3-[N,N{\textquoteright}-bis-3-(salicylidenamino)ethyltriamine] Mo(VI)O-2@SBA-15 has been synthesized by the anchoring of the 3-[N,N-bis-3-(salicylidenamino)ethyltriamine] ligand (L or Salpr) on the inner surfaces of organofunctionalized SBA-15 and subsequent complexation with Mo(VI) O-2(acac)(2). The physico-chemical properties of the functionalized catalysts were analyzed by elemental analysis, ICP-OES, XRD, N-2-sorption measurements, TG \& DTA, solid state C-13, Si-29 NMR spectroscopy, FT-IR, Raman spectroscopy, XPS, DRS UV-Vis spectroscopy, SEM and TEM. XRD and N-2 sorption analyses helped to find out the morphological and textural properties of the synthesized catalysts and confirm that an ordered mesoporous channel structure was retained even after the multistep synthetic procedures. The (100), (110) and (200) reflections in SBA-15 provide hints of a good structural stability, the existence of long range ordering and a high pore wall thickness. TG and DTA results reveal that the thermal stability of (L)Mo(VI)O-2@SBA-15 was maintained up to 300 degrees C. The organic moieties anchored over the surface of the SBA-15 support were determined by solid state C-13 NMR and FT-IR spectroscopy. Further, solid state Si-29 NMR spectroscopy provides the information about the degree of functionalization of the surface silanol groups with the organic moiety. The electronic environment and the oxidation state of the molybdenum site in (L)Mo(VI)O-2@SBA-15 were monitored by Raman spectroscopy, XPS and DRS UV-Vis techniques. Moreover, the morphology and topographic information of the synthesized catalysts were confirmed by SEM and TEM imaging. The synthesized catalysts were evaluated in epoxidation and sulfoxidation reactions, and the results show that (L)Mo(VI)O-2@SBA-15 exhibits high conversion and selectivity towards epoxidation and sulfoxidation reactions in combination with high stability. The anchored solid catalysts can be recycled effectively and reused several times without major loss in activity. In addition, Sheldon{\textquoteright}s hot filtration test was also carried out.

}, issn = {2046-2069}, doi = {10.1039/c3ra47222a}, author = {Lazar, Anish and Thiel, Werner R. and Singh, A. P.} } @article { ISI:000344525500041, title = {Synthesis of a recyclable and efficient Pd(II) 4-(2-pyridyl)-1,2,3-triazole complex over a solid periodic mesoporous organosilica support by {\textquoteleft}{\textquoteleft}click reactions{\textquoteright}{\textquoteright} for the stille coupling reaction}, journal = {RSC Advances}, volume = {4}, number = {81}, year = {2014}, month = {AUG}, pages = {43070-43079}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

A highly efficient, reusable B-PMO-TZ-Pd(II) catalyst was synthesized by anchoring 4-(2-pyridyl)-4-(2-pyridyl)-1,2,3-triazole ligand over the surface of an organo-functionalized benzene support containing periodic mesoporous organosilica (B-PMO) via {\textquoteleft}{\textquoteleft}click reaction{\textquoteright}{\textquoteright} and the subsequent complexation with PdCl2. B-PMO materials with uniform hexagonal arrangements were prepared using C-16 alkyl trimethyl ammonium bromide [CTAB] surfactant under basic conditions. The physiochemical properties of the functionalised catalyst were analysed by elemental analysis, ICP-OES, XRD, N-2 sorption, TGA \& DTA, solid state C-13, Si-29 NMR spectra, FT-IR, XPS, UV-vis, SEM and TEM. XRD and N-2 sorption revealed the morphological and textural properties of the synthesized catalyst, confirming that ordered mesoporous channel structure was retained even after the multistep synthetic procedure. The (100), (110) and (200) reflections in B-PMO are evidence of its good structural stability and the existence of long range order. The TGA-DTA results reveal that the synthesized catalyst B-PMO-TZ-Pd(II) was thermally stable, even at high temperature. The organic moieties anchored over the surface of B-PMO were demonstrated by solid state C-13 NMR and FT-IR spectroscopy. Solid state Si-29 NMR spectroscopy provides information about the degree of functionalization of the surface silanol group. The electronic environment and oxidation state of Pd in B-PMO-TZ-Pd(II) were monitored by XPS and UV-visible techniques. Moreover, the morphologies and topographic information of the synthesized B-PMO-TZ-Pd(II) catalyst were confirmed by SEM and TEM analyses. The catalytic properties of the catalyst for the Stille coupling reaction were screened, and higher catalytic activities with high TONs were observed. The anchored solid B-PMO-TZ-Pd(II) catalyst can be recycled efficiently and reused several (four) times without a major loss in reactivity.

}, issn = {2046-2069}, doi = {10.1039/c4ra06459c}, author = {Sharma, Priti and Singh, A. P.} } @article { ISI:000373408600014, title = {Correlating the role of hydrophilic/hydrophobic nature of Rh(I) and Ru(II) supported organosilica/silica catalysts in organotransformation reactions}, journal = {Applied Catalysis A-General}, volume = {513}, year = {2016}, month = {MAR}, pages = {138-146}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Highly reactive and hydrophobic triphenyl phosphine based rhodium(I) and ruthenium(II) organometallic complexes over benzene containing periodic mesoporous organosilica (PMOB) have been synthesized. This has been achieved by the immobilization of neat metal complexes like RhCl(PPh3)(3) [Wilkinson catalyst], RuHCl(CO)(PPh3)(3) and RuCl2(PPh3)(3) over aminofunctionalized PMOB to get RhCl(PPh3)(2)-PrNH2PMOB, RuHCl(CO)(PPh3)(2)-PrNH2PMOB and RuCl2(PPh3)(3)-PrNH2PMOB, respectively. The physico-chemical properties of the functionalized catalysts were analyzed by elemental analysis, ICP-OES, XRD, N-2 sorption analyses, FT-IR, solid state C-13 and Si-29 NMR spectra, XPS, SEM, TEM and contact angle measurements. The XRD and N-2 sorption analyses showed excellent textural properties with ordered mesoporous channel structure of all synthesized catalysts. The organic moieties anchored in PMOB were confirmed by C-13 CPMAS NMR and Fr-IR spectroscopy with Si-29 CPMAS NMR spectroscopy providing the information about the degree of functionalization of surface silanol groups with organic moiety. The Rh(I) and Ru(II) complexes supported on MCM-41/SBA-15/PMOE (ethane-PMO) were synthesized, and their catalytic activities in hydrogenation and sulfoxidation reactions were compared with Rh(I) and Ru(II) complexes supported on PMOB. The results show that PMOB based catalysts exhibit higher activities and selectivities than MCM-41/SBA-15/PMOB supported catalysts, neat homogeneous complexes and without catalyst. The better catalytic performance of PMOB based catalyst is attributed to the hydrophobic nature and high surface area of the PMOB support. The recycling studies of anchored catalysts show no major deactivation of the catalyst. (C) 2015 Elsevier B.V. All rights reserved.

}, keywords = {Heterogeneous catalysts, Hydrogenation and sulfoxidation, Hydrophobic, Periodic mesoporous organosilica}, issn = {0926-860X}, doi = {10.1016/j.apcata.2015.12.026}, author = {Lazar, Anish and George, Shoy C. and Jithesh, P. R. and Vinod, C. P. and Singh, A. P.} } @article {43057, title = {Organofunctionalization of vanadium(III) acetylacetonate complex over aminofunctionalized SBA-15 for sulfoxidation reactions}, journal = {Advanced Porous Materials}, volume = {4}, year = {2016}, month = {DEC}, pages = {212-218}, publisher = {American Scientific Publishers}, abstract = {

Recyclable SBA-15 supported aminopropyl vanadium(III) acetylacetonate heterogeneous catalyst has been synthesized by covalent anchoring of vanadium(III) acetylacetonate over aminofunctionalized SBA-15 via. post grafting method, V(III)(acac)3NH2@SBA-15. The synthesized catalyst was characterized by elemental analysis, ICP-OES, XRD, N2 sorption analysis, FT-IR, 29Si NMR spectroscopy, XPS, SEM and TEM. The percentage of nitrogen and vanadium in V(III)(acac)3NH2@SBA-15 was determined by elemental analysis and ICP-OES, respectively. XRD and N2 sorption analyses provide the information about the structural integrity (Mesoporous structure) and textural properties of all synthesized catalysts. The presence and degree of organofunctionalization on SBA-15 were monitored by FT-IR and 29Si NMR spectroscopy, respectively. Moreover, the oxidation state and the chemical environment of vanadium metal in V(III)(acac)3NH2@SBA-15 were revealed by XPS spectroscopy. Eventually, the morphology and topographic information of the synthesized catalysts were confirmed by SEM and TEM imaging. The synthesized catalyst was evaluated in oxidation of various sulfides and the results show that V(III)(acac)3NH2@SBA-15 catalyst exhibits higher conversion and selectivity towards the sulfoxidation reaction compared to the neat V(III)(acac)3 complex and blank reaction. The synthesized catalyst was recycled four times.

}, doi = {10.1166/apm.2016.1118}, author = {Lazar, Anish and Sanjush, K. S. and Singh, A. P.} } @article { ISI:000369533400015, title = {Phenylacetylene hydrogenation on Au@Ni bimetallic core-shell nanoparticles synthesized under mild conditions}, journal = {Catalysis Science \& Technology}, volume = {6}, number = {3}, year = {2016}, month = {JAN}, pages = {708-712}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

The synthesis of Au@Ni bimetallic core-shell nanoparticles through an energy efficient (lower temperature) route in oleylamine following a sequential reduction strategy is reported. The method is found to be useful for the synthesis of a very thin nickel shell (2 nm) over a gold core (15 nm). Synergistic effects are observed in catalyzing phenylacetylene hydrogenation under different solvent conditions.

}, issn = {2044-4753}, doi = {10.1039/c5cy02005k}, author = {Vysakh, A. B. and Lazar, Anish and Yadukiran, V. and Singh, A. P. and Vinod, C. P.} } @article { ISI:000374588500013, title = {Synthesis and characterization of nanoporous silica SBA-15 diaminocyclohexane and its application in removal of Cu(II) and Ni(II) from aqueous solution}, journal = {Desalination and Water Treatment}, volume = {57}, number = {33}, year = {2016}, month = {JUL}, pages = {15397-15409}, publisher = {TAYLOR \& FRANCIS INC}, address = {530 WALNUT STREET, STE 850, PHILADELPHIA, PA 19106 USA}, abstract = {

A new nanoporous 1,2-diaminocyclohexane-functionalized SBA-15 (Dach@SBA-15) silica sorbent was prepared. The structure and physicochemical properties of the material were characterized by elemental analysis, X-ray diffraction, transmission electron microscopy (TEM), scanning electron microscopy, FT-IR spectroscopy, nitrogen adsorption-desorption isotherms and thermogravimetric analysis. TEM image clearly showed the sheet-like structure of Dach@SBA-15. The organic functional groups were successfully grafted onto the SBA-15 surface and the ordering of the support was not affected by the chemical modification. The Dach@SBA-15was used as a sorbent for removal of Cu(II) and Ni(II) from aqueous solution. Experimental parameters like effect of pH, contact time and metal ion concentration were studied and optimized. The adsorption isotherm data fitted well to Langmuir isotherm model and the monolayer adsorption capacity values for Cu(II) was 90.09 and for Ni (II) was 84.03 mg/g at 303 K. The experimental kinetic data fitted very well to the pseudosecond- order model. The Dach@SBA-15 could be used as a sorbent for removal of Cu(II) and Ni(II) from aqueous medium.

}, keywords = {Adsorption, BET, FAAS, FT-IR, Heavy metals, Nanoporous silica}, issn = {1944-3994}, doi = {10.1080/19443994.2015.1072741}, author = {Sreenu, Bhogineni and Sharma, Priti and Seshaiah, Kalluru and Singh, A. P.} } @article { ISI:000373440600012, title = {Synthesis of new hybrid sorbent 2-mercaptobenzaldehyde SBA-15 and its application in solid phase extraction of Cd(II) from water and food samples}, journal = {Analytical Methods}, volume = {8}, number = {14}, year = {2016}, month = {MAR}, pages = {2947-2954}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {

In this paper, a new mesoporous hybrid material was fabricated by anchoring 2-mercaptobenzaldehyde (2MB) onto the surface of SBA-15. The adsorbent (2MB-SBA-15) was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption-desorption isotherm measurements and thermogravimetric analysis (TGA) and applied as a sorbent in the preconcentration of Cd(II) in water samples and food samples. The effect of various analytical parameters such as pH, dose of sorbent, amount of eluent, sample flow rate and interfering ions was investigated. The preconcentration capacity of the prepared material under optimized conditions for Cd(II) was 0.94 +/- 0.01 mmol g(-1). The Cd collected onto the sorbent was eluted out with 10 mL of 1 M HNO3 and determined by AAS. The LOD, LOQ and preconcentration factor of the present method were found to be 6.93 x 10(-6), 1.21 x 10(-5) mM and 100, respectively. The relative standard deviation for four preconcentration experiments was found to be \<= 5\%.

}, issn = {1759-9660}, doi = {10.1039/c5ay03031e}, author = {Sreenu, B. and Imran, K. and Seshaiah, K. and Sharma, Priti and Singh, A. P.} } @article {45731, title = {Exploration of amination reactions on highly extendable active sites of Pd(II)-3-allylsalicylaldiminophenol (ASIP) complex over thiofunctionalized SBA-15}, journal = {Microporous and Mesoporous Materials}, volume = {242}, year = {2017}, month = {APR}, pages = {173-181}, type = {Article}, abstract = {

An effective and impressive heterogeneous catalyst, Pd(II)-3-allylsalicylaldiminophenol-SBA-15, dubbed as Pd(II)ASIP@SBA-15, for amination reactions of aryl halides to synthesize secondary amines (2), has been synthesized and characterized. Pd(II)ASIP@SBA-15 has been synthesized by the covalent anchoring of 3-allylsalicylaldehyde over thiofunctionalized SBA-15, then further reaction with 2-aminophenol, followed by metallation process by using Pd(11)(OAc)(2). A specifically designed cheap and easily available organic ligand, 3-allylsalicylaldiminophenol (ASIP), was synthesized from 3-allylsalicylaldehyde and 2-aminophenol. Using this, the synthesis of Pd(II)ASIP@SBA-15 was carried out whereby the ligand providing an active co-ordination or chelating sites for palladium metal. This strategy helped in exposing the Pd(11)ASIP active sites from surface to channels of SBA-15 support during the reactions. The synthesized catalyst were characterized by CHN analysis, PXRD, Nitrogen sorption analyses, TG \& DTA, FTIR, C-13 and Si-29 CPMASS NMR spectra, XPS, UV-Visible, SEM, EDAX and TEM. Pd(II)ASIP@SBA-15 catalyst was screened in heterogeneous amination reactions of aryl halides to produce N-aryl derivatives or secondary amines with high catalytic activity as revealed by turn over frequency (TOF) calculations. To explore the heterogeneous nature of catalysts, amination reactions were carried with neat Pd(II)ASIP complex and Pd(11)(OAc)(2) catalysts. The catalyst was recycled several times without much loss of activity and Sheldon hot filtration test has been performed. (C) 2017 Elsevier Inc. All rights reserved.

}, keywords = {Amination Reactions, heterogeneous catalysis, Reusable, Supported catalysis}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2017.01.026}, author = {Lazar, Anish and Vinod, C. P. and Singh, A. P.} } @article {43778, title = {Heterogeneous route for transfer hydrogenation reactions of ketones using Ru(II)Cymene complex over modified benzene-organosilica (PMOB)}, journal = {Molecular Catalysis}, volume = {440}, year = {2017}, month = {OCT}, pages = {66-74}, type = {Article}, abstract = {An inorganic-organic hybrid catalyst, Ru(II)Cym@PMOB, was synthesized by anchoring of [Ru(II)Cl-2(Pcymene)](2) complex which is derived from a reaction between hydrated ruthenium(III) trichloride and ocphellandrene over aminofunctionalized benzene-organosilica (PMOB). In the context of secondary alcohol synthesis from ketones, transfer hydrogenation (TH) reactions are convenient compared to conventional hydrogenation reactions owing to its lower activation energy and ambient pressure and mild temperature reaction" conditions. The synthesized catalysts were characterized by CHN analysis, XRD, ICP, N-2-sorption analysis, TG \& DTA, FFIR,C-13 \& 29Si solid NMR, UV-vis, TEM, SEM and XPS. The catalytic activities of neat [Ru(II)C-12(p-cymene)]2 complex and Ru(II)Cym@PMOB were evaluated in transfer hydrogenation (TH) of ketones (-97\%) and compared with conventional hydrogenation reactions (-5\%) where molecular H-2 was used. The results showed Ru(II)Cym@PMOB as highly active catalyst towards transfer hydrogenation (TH) reaction of acetophenones compared to neat [Ru(II)Cl-2(p-cymene)(12) complex. The heterogeneity of Ru(II)Cym@PMOB was confirmed by Sheldon{\textquoteright}s test. (C) 2017 Elsevier B.V. All rights reserved.}, keywords = {Conventional Hydrogenation Reactions, Ru(II)Cym@PMOB, Transfer Hydrogenation Reaction, [Ru(II)Cl2(p-cymene)]2 complex}, doi = {10.1016/j.mcat.2017.07.018}, author = {Lazar, Anish and Silpa, S. and Prabhakaran, Vinod C. and Singh, A. P.} } @article {43822, title = {Highly active recyclable SBA-15-EDTA-Pd catalyst for Mizoroki-Heck, Stille and Kumada C-C coupling reactions}, journal = {Journal of Porous Materials}, volume = {24}, year = {2017}, month = {AUG}, pages = {837-846}, type = {Article}, abstract = {Highly efficient SBA-15-EDTA-Pd(11) heterogeneous catalyst was synthesized by covalent anchoring Pd-EDTA complex over organo-modified surface of SBA-15. SBA-15-EDTA-Pd(11) catalyst was found to exhibit excellent catalytic activity in appreciable yield for Heck, Stille and Kumada cross-coupling reactions. Catalytic system exhibited excellent activity for completion of reaction, isolation, Pd loading (0.87 mmol\%) and yields of products as compared to earlier reported heterogeneous supported Pd catalysts. Covalently anchored heterogeneous SBA-15-EDTA-Pd(11) catalyst can be recycled for more than five times without noticeable loss in activity and selectivity.}, doi = {10.1007/s10934-016-0323-8}, author = {Rathod, Jayant and Sharma, Priti and Pandey, Punam and Singh, A. P. and Kumar, Pradeep} } @article {45761, title = {Synthesis and characterization of D-2PA-Pd(II)@SBA-15 catalyst via {\textquoteleft}{\textquoteleft}click chemistry{\textquoteright}{\textquoteright}: highly active catalyst for Suzuki coupling reactions}, journal = {Journal of Porous Materials}, volume = {24}, year = {2017}, month = {APR}, pages = {327-340}, type = {Article}, abstract = {

Copper catalysed cycloaddition reaction between azide and terminal alkyne, called as {\textquoteleft}{\textquoteleft}click reaction{\textquoteright}{\textquoteright}, was found to be modular approach for the synthesis of facile, highly efficient and recoverable D-2PA-Pd(II)@SBA-15 catalyst. In efforts to synthesize the catalyst, the cycloaddition reaction between azido-functionalized mesoporous SBA-15 and N,N-dimethyl-2-propynylamine (D-2PA) has been carried out, followed by the complexation with PdCl2. To analyze physiochemical properties of synthesized materials, various characterization techniques such as CHN elemental analysis, X-ray diffraction, solid state C-13 and Si-29 NMR spectra, FT-IR, XPS, SEM, TEM and N-2 sorption analysis, TGA and DTA, UV-Vis spectroscopy have been carried out. The synthesized catalyst, D-2PA-Pd(II)@SBA-15, exhibited excellent catalytic activities with good product yield and high TON towards Suzuki coupling reaction of various aryl halides with phenylboronic acid. The effect of solvent, base and temperature on coupling reactions has also been described. The developed protocol offers recyclability of catalyst for multiple (four) times without any appreciable loss in stability and catalytic reactivity.

}, keywords = {Click reaction, Cycloaddition, mesoporous materials, SBA-15, Suzuki coupling}, issn = {1380-2224}, doi = {10.1007/s10934-016-0266-0}, author = {Pathak, Aruna and Singh, A. P.} } @article {44217, title = {Ru(II)-functionalized SBA-15 as highly chemoselective, acid free and sustainable heterogeneous catalyst for acetalization of aldehydes and ketones}, journal = {Catalysis Communications}, volume = {104}, year = {2018}, month = {JAN}, pages = {62-66}, type = {Article}, abstract = {

Combining electron deficient Ru(II) coordination sites with organofunctionalized SBA-15, (L)Ru(Il)@SBA-15, result in a mild, neutral, water scavenger free and chemo-selective acetalization catalyst for cyclic/acyclic acetals. Vacant coordination sites of ruthenium in (L)Ru(II)@SBA-15 activates protecting groups as well as reactants simultaneously and restricts the reverse acetalization reaction. Synthesized (L)Ru(Il)@SBA-15 catalyst has been thoroughly characterized and act as competitive catalyst compared to conventional acid catalysts. (L) RuaD@SBA-15 performs high catalytic activity as well as selectivity within 20 min with high TOF. The catalyst can be recycled and reaction parameters are optimized.

}, keywords = {Acetalization reactions, Acid free, chemo-selective, heterogeneous catalyst, Reusable, Ru(II) immobilized SBA-15}, issn = {1566-7367}, doi = {10.1016/j.catcom.2017.10.016}, author = {Lazar, Anish and Betsy, K. J. and Vinod, C. P. and Singh, A. P.} } @article {44585, title = {Synthesis of heterogeneous Ru(II)-1,2,3-triazole catalyst supported over SBA-15: application to the hydrogen transfer reaction and unusual highly selective 1,4-disubstituted triazole formation via multicomponent click reaction}, journal = {Catalysis Science \& Technology}, volume = {8}, year = {2018}, month = {JUL}, pages = {3246-3259}, abstract = {In the present study, we demonstrate a simple and efficient method for ligand formation and covalent anchoring to a heterogeneous support via click reaction. The complex tris(triphenylphosphine) ruthenium(II) dichloride [RuCl2(PPh3)(3)] anchored over the click modified ligand of SBA-15 forms a new highly efficient heterogeneous SBA-15-Tz-Ru(II) TPP catalyst. Solid state C-13, Si-29, and P-31 CP-MAS NMR spectra provide evidence for the formation of the heterogeneous catalyst. SBA-15-Tz-Ru(II) TPP catalyst was screened for the multicomponent click cycloaddition reaction in water medium as a green solvent and it exhibited unusual and excellent selectivity for the formation of 1,4-disubstituted triazole product under mild reaction condition. In addition, SBA-15-Tz-Ru(II) TPP catalyst also catalyzed the hydrogen transfer reaction of various carbonyl compounds with excellent catalytic activity to give the corresponding alcohols. The heterogeneous catalyst can be recycled and reused several times (five) without a loss in reactivity.}, doi = {10.1039/c7cy02619f}, author = {Sharma, Priti and Rathod, Jayant and Singh, A. P. and Kumar, Pradeep and Sasson, Yoel} }