Faculty Publications
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Item 4-Nitrobenzoic acid-sulfathiazole (1/1)(2014) Oruganti, M.; Trivedi, D.R.In the crystal structure of the title compound, C7H 5NO4·C9H9N3O 2S2, the sulfathiazole and 4-nitrobenzoic acid molecules are held together by short ?-? contacts between the thiazole and nitrobenzene rings, with a centroid-centroid distance of 3.8226(7)Å. The sulfathiazole molecules form dimers via N-H.N hydrogen bonds involving the thiazole and sulfonamide moieties, owing to the fact that sulfathizole exhibits amide-imide tautomerism. The N-H (amine) groups of two sulfathiazole molecules are linked to the two S=O groups of a sulfathiazole via N-H.O hydrogen bonds. Two molecules of coformer are held together by O-H.O hydrogen bonds. These units self-assemble, forming a three-dimensional network stabilized by (acid)C-H.?(sulfathiazole benzene ring) interactions.Item Identification of robust synthon in the molecular salts of 2-aminothiazole with substituted benzoic acids: A case study(Springer India sanjiv.goswami@springer.co.in, 2014) Oruganti, M.; Pallepogu, R.; Trivedi, D.R.Six new salts of an API intermediate 2-aminothiazole with different carboxylic acid coformers were synthesized and characterized by IR (Infrared spectroscopy), 1H-NMR, DSC (Differential scanning calorimetry), XRPD (X-ray powder diffraction) and single crystal XRD. The crystal structure of the salts with benzoic acid, 2,3-, 2,4-, 2,5-, 2,6- dihydroxybenzoic acids and 2,4-dinitrobenzoic acid were determined. The thiazole moiety exhibited solvent (polarity) assisted tautomerism in all reported salts and proton transfer was noticed to the ring N of thiazole due to which two point supramolecular synthon N+-H(thiazole)?O-(acid), N-H(amine)?O-(acid) was observed. The crystal structures were studied with respect to the positional effect of the competing functional groups like hydroxyl (-OH) and nitro (-NO2) as well as their donor and acceptor abilities for hydrogen bonding. The presence of the non-conventional hydrogen bond (C-H?O) has been found to play a critical role in the formation of secondary supramolecular architectures. © 2014 Indian Academy of Sciences.Item The hierarchies of hydrogen bonds in salts/cocrystals of isoniazid and its Schiff base - A case study(Royal Society of Chemistry, 2016) Oruganti, M.; Khade, P.; Das, U.K.; Trivedi, D.R.A series of two salts of isoniazid and two cocrystals of its Schiff base have been synthesised and characterized using FT-IR, 1H-NMR, DSC, XRPD and SCXRD. The crystal structures with 2,5-dihydroxybenzoic acid, 2,6-dihydroxy benzoic acid, 3-aminobenzoic acid and o-phthalic acid have been deduced. In all complexes the involvement of pyridine N (proton transfer/robust synthon) is noticed. The unit cell similarity index was calculated between two cocrystals (N-(propan-2-ylidene)isonicotinohydrazide)·(2,5-dihydroxybenzoic acid) and (3-aminobenozic acid)·(N-(propan-2-ylidene)isonicotinohydrazide). Furthermore, the index was compared with the reported complexes and it was found to be close to zero indicating isostructurality. The correlation between the NPyr-H?O (acid) hydrogen bond distance for the reported cocrystals and their corresponding pKa values has been deduced and validated. © The Royal Society of Chemistry 2016.Item Solid-state versatility of the molecular salts/cocrystals of 2-chloro-4-nitrobenzoic acid: A case study on halogen bonds(American Chemical Society, 2017) Oruganti, M.; Nechipadappu, S.K.; Khade, P.A.; Trivedi, D.R.2-Chloro-4-nitrobenzoic acid (2c4n) is an antiviral agent used for the treatment of HIV infection and to boost the immune response in immune deficiency diseases. In the present study, a series of eight molecular salts of 2c4n with pyridyl and benzoic acid derivatives have been synthesized by a crystal engineering approach and were characterized structurally by various spectroscopic, thermal, and X-ray diffraction techniques. Crystal structures of all synthesized molecular salts were determined by single-crystal X-ray diffraction techniques. In all synthesized molecular salts, the charge-assisted acid···pyridine/amine heterosynthon was found to be the primary supramolecular synthon. The synthesized salts, namely, 2c4n.g and 2c4n.h salts were found to be isostructural. Further, in the current work, the occurrence of weak halogen bonds in the presence of strong hydrogen bonds in the synthesized and in the reported molecular salts/cocrystals of 2c4n has been investigated. A detailed inspection of the crystal structures of salts/cocrystals of 2c4n was carried out to demonstrate the importance of halogen bonds in these crystal structures. It was found that 4 out of 8 synthesized molecular salts and 12 out of 24 reported molecular adducts of 2c4n were found to exhibit halogen bonds in their crystal structures. A similar kind of conformational change was observed for molecular salts exhibiting halogen bonds in their crystal structures; however, the conformations were found to be slightly different in other molecular salts. It was observed that two-point primary supramolecular synthon and stronger intramolecular Cl···O halogen bonds in the molecular adducts of 2c4n are found to be more susceptible to exhibit halogen bonds in their crystal structures. Halogen bond interactions played a vital role in the crystal stabilization of these molecular adducts. © 2017 American Chemical Society.Item Enhanced optical flow-based full reference video quality assessment algorithm(Springer, 2022) Gujjunoori, S.; Oruganti, M.; Pais, A.R.Full reference video quality assessment based on optical flow is emerging. Human Visual System (HVS) based video quality assessment algorithms are playing an important role in effectively assessing the distortions in video sequences. There exist very few video quality assessment algorithms which consider spatio-temporal distortions effectively. To address the above issues, we present an enhanced optical flow based full reference video quality algorithm which considers the orientation feature of the optical flow while computing the temporal distortions as opposed to the use of feature, minimum eigenvalue as in the state of the art. Further, it presents an interquartile range based comparative weighted closeness (INT-CWC) measure which aimed to measure the comparative dispersion of video quality scores of any two video quality assessment algorithms with DMOS scores. Here INT-CWC measure is a novel attempt. The performance of proposed scheme is evaluated using the LIVE dataset and scheme is shown to be competitive with, and even out-perform, existing video quality assessment algorithms. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.