@article { ISI:000230396800004, title = {Ti-oxo radicals and product selectivity in olefin oxidations over titanosilicate molecular sieves}, journal = {Zeitschrift f{\"u}r Physikalische Chemie International Journal of Research in Physical Chemistry and Chemical Physics}, volume = {219}, number = {7}, year = {2005}, month = {JUL}, pages = {905-920}, publisher = {OLDENBOURG VERLAG}, type = {Article}, address = {LEKTORAT MINT, POSTFACH 80 13 60, D-81613 MUNICH, GERMANY}, abstract = {

The O-O bond of Ti-oxo species (Ti-peroxo, Ti-hydroperoxo or Ti-superoxo) generated on titanosilicate molecular sieves contacted with H2O2 cleaves either heterolytically or homolytically. While the former type of O-O cleavage (generating non-radical reactive oxygen intermediates) leads to selective epoxide products, the latter (generating reactive oxygen radical intermediates, O-2(-center dot) and HOOcenter dot) results in non-sclective, allylic oxidation products in cyclohexene oxidation. These radicals were detected using EPR spin trapping techniques 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was used as the spin trap. Radical quenchers like hydroquinone suppressed their concentration and enhanced epoxide selectivity.

}, keywords = {cyclic voltammetry of titanosilicates, EPR-spin trap experiments, Molecular sieves, oxidations, product selectivity, reactive oxygen species, titaniunz-oxo radicals, Titanosilicates}, issn = {0942-9352}, doi = {10.1524/zpch.219.7.905.67088}, author = {Shetti, VN and Srinivas, D and Ratnasamy, P} } @article { ISI:000308836800013, title = {Aminolysis of epoxides catalyzed by three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16}, journal = {Journal of Catalysis}, volume = {293}, year = {2012}, month = {SEP}, pages = {126-140}, publisher = {ACADEMIC PRESS INC ELSEVIER SCIENCE}, address = {525 B ST, STE 1900, SAN DIEGO, CA 92101-4495 USA}, abstract = {

The application of three-dimensional, mesoporous titanosilicates (Ti-SBA-12 and Ti-SBA-16) as reusable, solid catalysts for the synthesis of a range of beta-amino alcohols in high yields and selectivity through ring-opening of epoxides with amines at ambient and solvent-free conditions is reported, for the first time. These mesoporous titanosilicates (Si/Ti = 20-80) were prepared by a direct hydrothermal synthesis route adjusting the concentration of HCl (0.05-2 M) used in the synthesis. Ti ions in these catalysts were mostly substituted for Si in the framework. Water adsorption and Si-29 magic-angle spin nuclear magnetic resonance spectroscopy revealed that Ti-SBA-16 is more hydrophobic than Ti-SBA-12. Mesoporosity, three-dimensional architecture, surface hydrophobicity and easy access of Lewis acidic, framework-substituted Ti sites are the factors responsible for the superior activity of Ti-SBA-16 compared to Ti-SBA-12 and the hitherto known solid catalysts for this reaction. (C) 2012 Elsevier Inc. All rights reserved.

}, keywords = {Aminolysis of epoxides, beta-Amino alcohol, Mesoporous titanosilicates, Molecular sieves, Ring opening of epoxides with amines, Ti-SBA-12, Ti-SBA-16}, issn = {0021-9517}, doi = {10.1016/j.jcat.2012.06.012}, author = {Kumar, Anuj and Srinivas, Darbha} } @article { ISI:000311350000009, title = {Selective oxidation of cyclic olefins over framework Ti-substituted, three-dimensional, mesoporous Ti-SBA-12 and Ti-SBA-16 molecular sieves}, journal = {Catalysis Today}, volume = {198}, number = {1, SI}, year = {2012}, month = {DEC}, pages = {59-68}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Framework Ti-substituted, three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, were prepared by direct hydrothermal synthesis method. These catalysts showed catalytic activity higher than the hitherto known titanosilicates for the oxidation of cyclic olefins (cyclohexene and cyclooctene) with tert.-butyl hydroperoxide. An epoxide selectivity of 100\% and olefin conversion greater than 92\% were obtained. Cubic Ti-SBA-16 with interconnected cage-like mesopore structure was more active than hexagonal Ti-SBA-12. X-ray diffraction and diffuse reflectance UV-vis, Fourier transform infrared, Raman and electron paramagnetic resonance spectroscopies provided evidence for the substitution of Ti4+ (for Si4+) in the framework locations. The catalytic activity correlated with the concentration of framework-substituted, tetrahedral Ti4+ ions. Easy accessibility of the active sites and the three-dimensional mesoporous structure are the possible causes for the superior activity of these titanosilicate catalysts. (C) 2012 Elsevier B. V. All rights reserved.

}, keywords = {Epoxidation of cyclic olefins, mesoporous materials, Molecular sieves, Selective oxidation, Ti-SBA-12, Ti-SBA-16, Titanosilicates}, issn = {0920-5861}, doi = {10.1016/j.cattod.2012.01.035}, author = {Kumar, Anuj and Srinivas, Darbha} } @article { ISI:000315176600016, title = {Hydroxylation of phenol with hydrogen peroxide catalyzed by Ti-SBA-12 and Ti-SBA-16}, journal = {Journal of Molecular Catalysis A-Chemical}, volume = {368}, year = {2013}, month = {MAR}, pages = {112-118}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

We report here, for the first time, the application of ordered, three-dimensional, mesoporous titanosilicates, Ti-SBA-12 and Ti-SBA-16, as reusable solid catalysts, for hydroxylation of phenol, an industrially important organic transformation. The reactions were conducted using 30\% aqueous H2O2 as oxidant. The catalysts of this work are more efficient than the hitherto known mesoporous Ti-silicates. They are more para-product selective than TS-1 and other titanosilicates. Ti-SBA-12 exhibited higher activity and hydroquinone/catechol selectivity (by nearly two times) than Ti-SBA-16. H2O2 efficiency of similar to 90 mol\% was obtained. Our study reveals that framework substituted Ti with pseudo-tetrahedral geometry, three-dimensional mesoporosity as well as surface structure are the unique features responsible for the high catalytic activity and selectivity of these titanosilicate catalysts. (C) 2012 Elsevier B.V. All rights reserved.

}, keywords = {Catalytic liquid-phase hydroxylation of phenol, Molecular sieves, Ordered mesoporous titanosilicates, Oxidation with hydrogen peroxide, Ti-SBA-12, Ti-SBA-16}, issn = {1381-1169}, doi = {10.1016/j.molcata.2012.11.026}, author = {Kumar, Anuj and Srinivas, Darbha} } @article { ISI:000328665300008, title = {Effect of SnO2/Al2O3 ratio of Si-based MFI on its acidity and hydrophobicity: application in selective hydroxyalkylation of p-cresol}, journal = {Catalysis Communications}, volume = {44}, number = {SI}, year = {2014}, month = {JAN}, pages = {29-34}, publisher = {ELSEVIER SCIENCE BV}, type = {Article}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Silica based MR type molecular sieves with various SnO2/Al2O3 ratios were synthesized from gels having molar compositions SiO2:xSnO(2):yAl(2)O(3):0.23(TPA)(2)O:35H(2)O where 0 \<= x \<= 0.02 and 0 \<= y \<= 0.01. Recyclable, Al-free Sn-MFI catalyst showed 31\% conversion of formaldehyde with 100\% selectivity to 2,2{\textquoteright}-methylenebis(4-methylphenol) in hydroxyalkylation of p-cresol with formaldehyde on account of moderate acidity and higher hydrophobicity. (C) 2013 Elsevier B.A. All rights reserved.

}, keywords = {Al-27 MAS NMR, Hydroxyalkylation, Molecular sieves, p-Cresol, Stannosilicate}, issn = {1566-7367}, doi = {10.1016/j.catcom.2013.08.002}, author = {Garade, Ajit C. and Malwadkar, A. V. and Niphadkar, P. S. and Jha, Ratnesh Kumar and Joshi, P. N. and Rode, C. V.} } @conference {45949, title = {Molecular sieves and ultrasound-assisted synthesis of novel 1,3,4-oxadiazole-2-thiones derivatives as potential antifungal agents}, booktitle = {19TH INTERNATIONAL ELECTRONIC CONFERENCE ON SYNTHETIC ORGANIC CHEMISTRY}, year = {2015}, publisher = {MDPI; Univ Sanitiago Compostila; SES; Flow Chemistry; REGAL S; Molecules}, organization = {MDPI; Univ Sanitiago Compostila; SES; Flow Chemistry; REGAL S; Molecules}, address = {ST. ALBAN-ANLAGE 66, BASEL, CH-4052, SWITZERLAND}, abstract = {

In the category of microorganism, fungi are considered as the special class of microbes responsible for opportunistic pathogenic infections in humans species. Due to the side effects of commercially available antifungal drugs and the emergence of new drug resistant fungal species in the past few years, has forced the researchers to search for novel and efficient antifungal drug molecules. The 1,3,4-oxadiazoles scaffold is associated with diverse biological activities. The multipurpose use of the Mannich bases in pharmaceutical chemistry promote us to prepare a new series of 5-(4-(benzyloxy)substituted phenyl)-3-((phenyl amino)methyl)-1,3,4oxadiazole-2(3H)-thione as antifungal agents. Herein, we report molecular sieves and ultrasound assisted synthesis of novel series of Mannich bases of the 5-substituted 1,3,4-oxadiazole-2-thiones by amino methylation with paraformaldehyde and substituted primary / secondary amines and their evaluation for antifungal activity. The structures of the newly synthesized compounds were determined by IR, NMR and Mass spectral study. The synthesized compounds exhibited interesting moderate to excellent antifungal activity against Candida albicans (NCIM 3557), Candida albicans(NCIM3471), Candida glabrata(NCIM3237), Cryptococcus neoformans (NCIM 3542), Cryptococcus neoformans(NCIM 3378), Aspergillus fumigates(NCIM 902), Aspergillus niger(NCIM 628) using Flucanazole as a standard reference drug. The synthesised compounds 6d, 6f,6g, 6h and 6j exhibited promising antifungal activity as antifungal agents.

}, keywords = {1, 3, 4-oxadiazoles, Antifungal activity, Mannich reaction, Molecular sieves, Ultrasound -assisted}, doi = {10.3390/ecsoc-19-b008}, author = {Nikalje, Anna Pratima G. and Nimbalkar, Ms Urja D. and Tupe, Santosh and Vazquez, Julio A. Seijas and Tato, Maria Pilar Vazquez}, editor = {Seijas, JA and Tato, MPV and Lin, SK} } @article { ISI:000380241600003, title = {Ultrasound- and molecular sieves-assisted synthesis, molecular docking and antifungal evaluation of 5-(4-(benzyloxy)-substituted phenyl)-3-((phenylamino)methyl)-1,3,4-oxadiazole-2(3H)-thiones}, journal = {Molecules}, volume = {21}, number = {5}, year = {2016}, month = {MAY}, pages = {484}, publisher = {MDPI AG}, address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND}, abstract = {

A novel series of 5-(4-(benzyloxy) substituted phenyl)-3-((phenyl amino) methyl)-1,3,4-oxadiazole-2(3H)-thione Mannich bases 6a-o were synthesized in good yield from the key compound 5-(4-(benzyloxy) phenyl)-1,3,4-oxadiazole-2(3H)-thione by aminomethylation with paraformaldehyde and substituted amines using molecular sieves and sonication as green chemistry tools. The antifungal activity of the new products was evaluated against seven human pathogenic fungal strains, namely, Candida albicans ATCC 24433, Candida albicans ATCC 10231, Candida glabrata NCYC 388, Cryptococcus neoformans ATCC 34664, Cryptococcus neoformans PRL 518, Aspergillus fumigatus NCIM 902 and Aspergillus niger ATCC 10578. The synthesized compounds 6d, 6f, 6g, 6h and 6j exhibited promising antifungal activity against the tested fungal pathogens. In molecular docking studies, derivatives 6c, 6f and 6i showed good binding at the active site of C. albicans cytochrome P450 enzyme lanosterol 14 alpha-demethylase. The in vitro antifungal activity results and docking studies indicated that the synthesized compounds have potential antifungal activity and can be further optimized as privileged scaffolds to design and develop potent antifungal drugs.

}, keywords = {1, 3, 4-oxadiazoles, Antifungal activity, Mannich reaction, Molecular docking, Molecular sieves, Ultrasound}, issn = {1420-3049}, doi = {10.3390/molecules21050484}, author = {Nimbalkar, Urja D. and Tupe, Santosh G. and Seijas Vazquez, Julio A. and Khan, Firoz A. Kalam and Sangshetti, Jaiprakash N. and Nikalje, Anna Pratima G.} }