@article { ISI:000261163000013, title = {Structural elucidation of propargylated products of 3-substituted-1,2,4-triazole-5-thiols by NMR techniques}, journal = {Magnetic Resonance in Chemistry}, volume = {46}, number = {12}, year = {2008}, month = {DEC}, pages = {1168-1174}, publisher = {JOHN WILEY \& SONS LTD}, address = {THE ATRIUM, SOUTHERN GATE, CHICHESTER PO19 8SQ, W SUSSEX, ENGLAND}, abstract = {

Propargylation of 3-substituted-1,2,4-triazole-5-thiols, which predominantly exist as their thione tautomers, was carried out with the view to synthesize different heterocycles and study their biological activity. Three different products namely, a mono S-propargyl and two S,N-dipropargyl regioisomers, arising from N1/N2 substitution, were isolated and characterized. Unambiguous structural elucidation of the regioisomers of S,N-dipropargyl derivatives was achieved by means of (13)C-(1)H HMBC technique. The proportion of the regioisomers was found to vary with the substituent on the 1,2,4-triazole thiols. No product corresponding to N4 substitution was isolated from any of the reactions carried out. Copyright (C) 2008 John Wiley \& Sons, Ltd.

}, keywords = {(1)H NMR, (13)C NMR, (15)N NMR, 1, 2, 4-triazoles, HMBC, NMR, Regioisomers}, issn = {0749-1581}, doi = {10.1002/mrc.2307}, author = {Chaudhary, Preeti M. and Chavan, Sayalee R. and Kavitha, M. and Maybhate, Shailaja P. and Deshpande, Sunita R. and Likhite, Anjali P. and Rajamohanan, P. R.} } @article { ISI:000319417100005, title = {Design, synthesis, structural characterization by IR, 1H, 13C, 15N, 2D-NMR, X-ray diffraction and evaluation of a new class of phenylaminoacetic acid benzylidene hydrazines as pfENR inhibitors}, journal = {Chemical Biology \& Drug Design}, volume = {81}, number = {6}, year = {2013}, month = {JUN}, pages = {715-729}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

Recent studies have revealed that plasmodial enoyl-ACP reductase (pfENR, FabI), one of the crucial enzymes in the plasmodial type II fatty acid synthesis II (FAS II) pathway, is a promising target for liver stage malaria infections. Hence, pfENR inhibitors have the potential to be used as causal malarial prophylactic agents. In this study, we report the design, synthesis, structural characterization and evaluation of a new class of pfENR inhibitors. The search for inhibitors began with a virtual screen of the iResearch database by molecular docking. Hits obtained from the virtual screen were ranked according to their Glide score. One hit was selected as a lead and modified to improve its binding to pfENR; from this, a series of phenylamino acetic acid benzylidene hydrazides were designed and synthesized. These molecules were thoroughly characterized by IR, 1H, 13C, 15N, 2D-NMR (COSY, NOESY, 1H-13C, 1H-15N HSQC and HMBC), and X-ray diffraction. NMR studies revealed the existence of conformational/configurational isomers around the amide and imine functionalities. The major species in DMSO solution is the E, E form, which is in dynamic equilibrium with the Z, E isomer. In the solid state, the molecule has a completely extended conformation and forms helical structures that are stabilized by strong hydrogen bond interactions, forming a helical structure stabilized by N-H...O interactions, a feature unique to this class of compounds. Furthermore, detailed investigation of the NMR spectra indicated the presence of a minor impurity in most compounds. The structure of this impurity was deduced as an imidazoline-4-one derivative based on 1H-13C and 1H-15H HMBC spectra and was confirmed from the NOESY spectra. The molecules were screened for in vitro activity against recombinant pfENR enzyme by a spectrophotometric assay. Four molecules, viz. 17, 7, 10, and 12 were found to be active at 7, 8, 10, and 12m concentration, respectively, showing promising pfENR inhibitory potential. A classification model was derived based on a binary QSAR approach termed recursive partitioning (RP) to highlight structural characteristics that could be tuned to improve activity.

}, keywords = {ADMET, docking, enoyl-ACP reductase, FabI, hydrogen bonding, NMR, phenylaminoacetic acid benzylidene hydrazine, Plasmodium falciparum, Plasmodium falciparum enoyl-ACP reductase, QSAR, recursive partitioning, X-ray diffraction}, issn = {1747-0277}, doi = {10.1111/cbdd.12118}, author = {Samal, Ramanuj P. and Khedkar, Vijay M. and Pissurlenkar, Raghuvir R. S. and Bwalya, Angela Gono and Tasdemir, Deniz and Joshi, Ramesh A. and Rajamohanan, P. R. and Puranik, Vedavati G. and Coutinho, Evans C.} } @article { ISI:000326674800001, title = {GIAO/DFT studies on 1,2,4-triazole-5-thiones and their propargyl derivatives}, journal = {Magnetic Resonance in Chemistry}, volume = {51}, number = {12}, year = {2013}, month = {DEC}, pages = {767-774}, publisher = {WILEY-BLACKWELL}, address = {111 RIVER ST, HOBOKEN 07030-5774, NJ USA}, abstract = {

Density functional theory (DFT)/Becke-Lee-Yang-Parr (B3LYP) and gauge-including atomic orbital (GIAO) calculations were performed on a number of 1,2,4-triazole derivatives, and the optimized structural parameters were employed to ascertain the nature of their predominant tautomers. C-13 and N-15 NMR chemical shifts of 3-substituted 1,2,4-triazole-5-thiones and their propargylated derivatives were calculated via GIAO/DFT approach at the B3LYP level of theory with geometry optimization using a 6-311++G** basis set. A good agreement between theoretical and experimental C-13 and N-15 NMR chemical shifts could be found for the systems investigated. The data generated were useful in predicting N-15 chemical shifts of all the nitrogen atoms of the triazole ring, some of which could not be obtained in solution state N-15 HMBC/HSQC NMR measurements. The energy profile computed for the dipropargylated derivatives was found to follow the product distribution profile of regioisomers formed during propargylation of 1,2,4-triazole thiones. Copyright (c) 2013 John Wiley \& Sons, Ltd.

}, keywords = {1, 2, 4-triazole-5-thiones, C-13, DFT, GIAO, N-15, NMR, Regioisomers, tautomers}, issn = {0749-1581}, doi = {10.1002/mrc.4012}, author = {Phalgune, Usha D. and Vanka, Kumar and Rajamohanan, P. R.} } @article { ISI:000329266500032, title = {Structural investigations of porous MgCl2-2-butanol molecular adduct as support for olefin polymerization}, journal = {Applied Catalysis A-General}, volume = {469}, year = {2014}, month = {JAN}, pages = {267-274}, publisher = {ELSEVIER SCIENCE BV}, address = {PO BOX 211, 1000 AE AMSTERDAM, NETHERLANDS}, abstract = {

A new heterogeneous Ziegler-Natta (Z-N) catalyst support material, MgCl2 center dot 4(CH3CH(OH)CH2CH3) (Mg2BuOH) has been synthesized. 2-Butanol, a linear, secondary alcohol was chosen for the generation of an active MgCl2 support which results in a Z-N catalyst with TiCl4. Significant feature of this work is the formation of rod shaped molecular adduct with highly porous character. Adduct material is characterized by XRD, TG-DTA, Raman spectroscopy, solid-state NMR and SEM. Activity of the Z-N catalyst supported on Mg2BuOH for ethylene polymerization is comparable with that of commercially available heterogeneous Z-N catalyst. However, there is scope to improve the activity by optimizing textural properties. (C) 2013 Elsevier B.V. All rights reserved.

}, keywords = {heterogeneous catalysis, MgCl2, Molecular adduct, NMR, Polyolefin, Ziegler-Natta catalyst}, issn = {0926-860X}, doi = {10.1016/j.apcata.2013.10.002}, author = {Thushara, K. S. and Ajithkumar, Thalasseril G. and Rajamohanan, P. R. and Gopinath, Chinnakonda S.} }