@article { ISI:000272560400015, title = {Immobilization of phosphotungstic acid (PTA) on imidazole functionalized silica: evidence for the nature of PTA binding by solid state NMR and reaction studies}, journal = {Journal of Physical Chemistry C}, volume = {113}, number = {50}, year = {2009}, month = {DEC}, pages = {21114-21122}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Phosphotungstic acid (PTA) immobilized onto imidazole functionalized fumed silica and was used its an efficient catalyst for epoxidation of a variety of olefins using aqueous H(2)O(2) as all oxidant. Negligible leaching of PTA under the reaction conditions employed indicates a strong interaction between PTA and imidazole The immobilized catalysts Could be separated and reused after the catalytic cycle Evidence for the heterogenization of PTA oil the imidazole functionalized fumed silica has been inferred from different spectroscopic techniques like IR, UV-vis, and NMR. Importantly, the nature of binding of PTA oil the support has been studied in detail by solid state NMR spectroscopy using (15)N labeled imidazole Support. It is clear from the NMR Studies that the effective heterogenization of PTA is mainly due to imidazolium ion Formation oil the support by the acidic protons of PTA and the resultant ion pair

}, issn = {1932-7447}, doi = {10.1021/jp906108e}, author = {Sofia, L. T. Aany and Krishnan, Asha and Sankar, M. and Raj, N. K. Kala and Manikandan, Palanichamy and Rajamohanan, P. R. and Ajithkumar, Thalasseril G.} } @article { ISI:000271252400004, title = {Incorporation of tin in different types of pores in SBA-15: synthesis, characterization and catalytic activity}, journal = {Microporous and Mesoporous Materials}, volume = {126}, number = {3}, year = {2009}, month = {DEC}, pages = {234-244}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Mesoporous Sn-SBA-15 has been synthesized by three different methods Such as conventional hydrothermal route, using cocatalyst NH4F and in the presence of organosilane precursor. All the materials are thoroughly characterized by powder X-ray diffraction (XRD), SEM. TEM. N-2 sorption and surface area measurements, diffuse-reflectance UV-visible and FTIR spectroscopy. TG-DTA and elemental analysis through ICP. Nitrogen adsorption data, XRD patterns, and TEM observations Suggests that the textural properties are retained during the isomorphous substitution of silicon by tin. ICP chemical analysis indicates that tin can be substituted in the range of S-l/S-n = 69-162. UV-visible spectra of samples synthesized by the cocatalytic approach exhibit unique absorption band at 213 nm characteristics of tin atom substituted in the smaller pores (2-3 nm) located inside the walls of mesopores. Further, an additional band at 224 nm can be assigned to Sri atoms located in the distorted tetrahedral position along the primary mesopores. In contrary, only one absorption band centered at 224 nm is observed for all the samples synthesized by conventional hydrothermal as well as in the presence of organosilane precursor. F-19 NMR spectra confirmed (no signal) the absence of occluded F- ions in the samples made with NH4F. Observed high catalytic activity in Baeyer-Villiger oxidation and Meerwin-Pondorf-Verly reduction under the liquid-phase conditions suggest the incorporation of a portion of tin in the smaller pores for the Sn-SBA-15 materials synthesized through cocatalyst method. (C) 2009 Elsevier Inc. All rights reserved.

}, keywords = {Baeyer-Villiger oxidation, catalysis, Functionalization of mesopores, Meerwin-Pondorf-Verly reduction, Sn-SBA-15}, issn = {1387-1811}, doi = {10.1016/j.micromeso.2009.05.038}, author = {Sasidharan, M. and Kiyozumi, Y. and Mal, N. K. and Paul, M. and Rajamohanan, P. R. and Bhaumik, Asim} } @article { ISI:000274929000006, title = {In situ encapsulation of pt nanoarchitectures of varying morphologies in mesoporous compounds}, journal = {Chemistry of Materials}, volume = {22}, number = {5}, year = {2010}, month = {MAR}, pages = {1633-1639}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Nanoparticle morphology could be engineered and fine-tuned based on a novel in situ template method Different shapes of platinum nanoparticles were obtained from very low concentrations of precursors and could be isolated exclusively inside the mesochannels of SBA-15 This was achieved by dispersing a platinum precursor in surfactant modified polymer to different extents and using these composite materials as templates for the formation of mesoporous silica [PtCl(6)](2-) interacts with the cationic headgroup of the surfactant and facilitates the isolation of precursors within the composite template leading to the formation of nanoparticles molded by the walls of the mesochannels when calcined When this [PtCl(6)](2-)-surfactant-polymer micelle composite is aged for different duration, Pt nanoparticles of various morphologies like spheroids, nano rugby balls, and nanorods are obtained

}, issn = {0897-4756}, doi = {10.1021/cm9036499}, author = {Prashar, Atul K. and Hodgkins, Robert P. and Chandran, Jima N. and Rajamohanan, P. R. and Devi, R. Nandini} } @article { ISI:000279787200004, title = {Isolation, structure, and functional elucidation of a modified pentapeptide, cysteine protease inhibitor (CPI-2081) from streptomyces species 2081 that exhibit inhibitory effect on cancer cell migration}, journal = {Journal of Medicinal Chemistry}, volume = {53}, number = {14}, year = {2010}, month = {JUL}, pages = {5121-5128}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

Cysteine proteases play an important role in cell migration and tumor metastasis. Therefore, their inhibitors are of colossal interest, having potential to be developed as effective antimetastatic drugs for tumor chemotherapy. Traditionally, secondary metabolites from streptomyces show a wide range of diversity with respect to their biological activity and chemical nature. In this article, we have described the characterization of small molecule cysteine protease inhibitor, CPI-2081 (compound 1), a mixture of two novel pentapeptides, compound 1a (736.71 Da), and compound 1b (842.78 Da), isolated from Streptomyces species NCIM2081, following solvent extraction and repeated HPLC based on C18 chemistry, and completely characterized using a variety of both ID and 2D NMR spectroscopy. Further, it was found that nanomolar concentration of compound 1 is able to inhibit papain hydrolytic activity. Also, compound 1 significantly inhibits tumor cell migration at sub cytotoxic concentration, indicating its remarkable potential to be developed as antimetastatic drug, which will make chemotherapy more localized and specific, thereby minimizing the hazardous side effects on normal tissues.

}, issn = {0022-2623}, doi = {10.1021/jm9014179}, author = {Singh, Jay Prakash and Tamang, Sudarsan and Rajamohanan, P. R. and Jima, N. C. and Chakraborty, Goutam and Kundu, Gopal C. and Gaikwad, Sushama M. and Khan, Mohammad Islam} } @article { ISI:000295149400011, title = {In situ encapsulation of Pt nanoparticles in mesoporous silica: synthesis, characterisation and effect of particle size on CO oxidation}, journal = {Applied Catalysis A-General}, volume = {403}, number = {1-2}, year = {2011}, month = {AUG}, pages = {91-97}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

Pt nanoparticles of narrow size distribution and average particle size of 4.4 nm are isolated exclusively inside SBA-12 mesoporous silica by a novel in situ method. The interaction of Pt precursor with surfactant-polymer composite micelle is followed by NMR and UV studies. The final Pt incorporated silica material is characterised by XRD, TEM and N(2) adsorption. The mesoporous nature of the silica is found to be intact after Pt incorporation without any pore blockage. CO oxidation activity of this material is compared with that of mesoporous silica incorporating different sizes of Pt viz., 1.8, 3.6 and 8 nm. Activation energies of CO oxidation for all these materials are calculated by a simple differential method based on first principles. A comparison of activation energies and single site yields reveals that these parameters are distinguishably less in catalyst containing 1.8 nm Pt nanoparticles but more or less same in catalysts containing 3.6, 4.4 and 8 nm Pt nanoparticles. (C) 2011 Elsevier B.V. All rights reserved.

}, keywords = {CO oxidation, In situ synthesis, Mesoporous silica, Pt nanoparticle}, issn = {0926-860X}, doi = {10.1016/j.apcata.2011.06.016}, author = {Prashar, Atul K. and Mayadevi, S. and Rajamohanan, P. R. and Devi, R. Nandini} } @article { ISI:000340826700002, title = {Isolation, characterization and antihyperlipidemic activity of secoisolariciresinol diglucoside in poloxamer-407-induced experimental hyperlipidemia}, journal = {Pharmaceutical Biology}, volume = {52}, number = {9}, year = {2014}, month = {SEP}, pages = {1094-1103}, publisher = {INFORMA HEALTHCARE}, address = {TELEPHONE HOUSE, 69-77 PAUL STREET, LONDON EC2A 4LQ, ENGLAND}, abstract = {

Context: Linum usitatissimum L. (Linaceae), commonly known as flaxseed, is a good source of dietary fiber and lignans. Earlier we reported cardioprotective, antihyperlipidemic, and in vitro antioxidant activity of flax lignan concentrate (FLC) obtained from flaxseed. Objectives: To isolate secoisolariciresinol diglucoside (SDG) from FLC and to evaluate the antihyperlipidemic activity of SDG in poloxamer-407 (P-407)-induced hyperlipidaemic mice. Material and methods: FLC was subjected to column chromatography and further subjected to preparative HPTLC to isolate SDG. The chemical structure of the isolated compound was elucidated by UV, IR, H-1 NMR, C-13 NMR, DEPT, COSY, HSQC, HMBC, ROESY, MS, and specific optical rotation was recorded. Further, we have investigated the antihyperlipidaemic effect of SDG (20 mg/kg) in P-407-induced hyperlipidaemic rats. Hyperlipidaemia was induced by intraperitoneal administration of P-407 (30\% w/v). Serum lipid parameters such as total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) levels were measured. Results and discussion: The structure and stereochemistry of the isolated compound were confirmed on the basis of 1D and 2D spectral data and characterized as SDG. Finally, isolated pure SDG was screened using a P-407-induced mice model for its antihyperlipidemic action using serum lipid parameters. The isolated SDG (20 mg/kg) significantly reduced serum cholesterol, triglyceride (p\<0.001), very low-density lipoprotein (p\<0.05), and non-significantly increased HDL-C. Conclusion: Finally, it was concluded unequivocally that SDG showed antihyperlipidaemic effects in P-407-induced hyperlipidaemic mice. Isolated pure SDG confirms that SDG is beneficial in the prevention of experimental hyperlipidemia in laboratory animals.

}, keywords = {column chromatography, flaxseed, Linum usitatissimum}, issn = {1388-0209}, doi = {10.3109/13880209.2013.877492}, author = {Zanwar, Anand A. and Hegde, Mahabaleshwar V. and Rojatkar, Supada R. and Sonawane, Kiran B. and Rajamohanan, P. R. and Bodhankar, Subhash L.} } @article { ISI:000361424000014, title = {Insertion copolymerization of difunctional polar vinyl monomers with ethylene}, journal = {ACS Macro Letters}, volume = {4}, number = {9}, year = {2015}, month = {SEP}, pages = {933-937}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A single-step synthesis, structural characterization and application of a neutral, acetonitrile ligated, palladium-phosphinesulfonate complex [{P\<\^\>O}PdMe(L)] (P\<\^\>O = K-2-P,O Ar2PC6H4SO2O with Ar = 2-MeOC6H4; L = CH3CN) (3) in coordination/insertion copolymerization of ethylene with difunctional olefin is investigated. In a significant development, complex 3 was found to catalyze insertion copolymerization of industrially relevant 1,1-disubstituted difunctional vinyl monomers for the first time. Thus, insertion copolymerization of ethyl-2-cyanoacrylate (ECA or super glue) and trifluoromethyl acrylic acid (TFMAA) with ethylene produced the corresponding copolymers with 6.5\% ECA and 3\% TFMAA incorporation. Increasing the concentration of difunctional olefins led to higher incorporation but at the expense of lower activities. These observations indicate that complex 3 tolerates difunctional vinyl monomers and provides direct access to difunctional polyolefins that have not been attempted before.

}, issn = {2161-1653}, doi = {10.1021/acsmacrolett.5b00562}, author = {Gaikwad, Shahaji R. and Deshmukh, Satej S. and Gonnade, Rajesh G. and Rajamohanan, P. R. and Chikkali, Samir H.} } @article { ISI:000360415500044, title = {Insights into the molecular dynamics in polysulfone polymers from C-13 solid-state NMR experiments}, journal = {Journal of Physical Chemistry B}, volume = {119}, number = {34}, year = {2015}, month = {AUG}, pages = {11287-11294}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

The molecular and segmental motions in three different grades of ductile polysulfone polymers; poly(ether sulfone) (PESU), polysulfone (PSU), and poly(phenyl sulfone) (PPSU) are probed using C-13 solid-state NMR experiments. Polarization inversion spin exchange at magic angle (PISEMA) experiments indicates that the phenyl rings in the polymers are undergoing pi-flip motions on the order of 100 kHz. The temperature dependent PISEMA experiments show that the fraction of mobile regions that undergoes aromatic pi-flips is higher in PPSU than in the other two polymers. The center band only detection of exchange (CODEX) experiments was carried out and was unable to detect any slow segmental motions in the chains. A combination of C-13 spin-lattice relaxation time (T-1) and T-1-filtered PISEMA experiments show that the mobile regions in all the polymers are dynamically heterogeneous.

}, issn = {1520-6106}, doi = {10.1021/acs.jpcb.5b03103}, author = {Eldho, Kavalakal Mathai and Rajamohanan, P. R. and Anto, Ralf and Bulakh, Neelima N. and Lele, Ashish K. and Ajithkumar, Thalasseril G.} }