Browsing by Author "Tiwari, Priyanka"

Now showing 1 - 4 of 4
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    Indium(III) and organotin(IV) 2-(methoxycarbonyl)benzenethiolates: Synthesis, structure and properties
    (Elsevier B.V., 2022) Kumar, Krishna; Tiwari, Priyanka; Moharana, Srikanta; Kant, Rajni; Bhattacharya, Subrato
    Two compounds In(mts)3, 1 and triphenyltin(mts), 2 [where mts = 2-(methoxycarbonyl) ben- zenethiolate] were synthesized and characterized. Both the compounds crystallize in the monoclinic system; 1 with space group P21/c and 2 with space group P21/n. Molecule 1 has a distorted trigonal bipyramidal geometry around the In(III) center. In the case of 1, out of the three mts ligands, two bind (S and O) bidentately while the third one binds mainly through its S atom, whereas 2 has a tetrahedral geometry around Sn(IV) center in which the mts ligand is bonded through its S atom only. Hirshfeld analyses were carried out to understand the nature of weak interactions responsible for the deviation from the ideal geometry of both compounds. Quantum chemical calculations were carried out at the DFT level using B3LYP functional in order to get the optimized geometry and vibrational frequencies. Natural bond orbital analyses (NBO) were performed to explore hyper-conjugative interaction energies, HOMO-LUMO, and various inter and intramolecular transitions. The thermodynamic profiles and electrostatic potential surfaces of the compounds have been investigated. Bulk properties such as dielectric loss/constant and AC conductivities have also been explored. � 2022 Elsevier B.V.
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    Properties and types of chitosan-based nanomaterials
    (Elsevier, 2022) Tiwari, Priyanka; Sharma, Anand; Nayak, Vanya; Verma, Ranjana; Singh, Jay
    This chapter briefly discusses immense research on chitosan-based nanomaterials as well as also highlights the current developments and their utility in different applications majorly focusing on the biomedical field. Chitosan is a well-known nontoxic, biocompatible, and biodegradable polymer possessing enormous possibilities for structural modification either by chemical or mechanical pathways, thereby generating novel polymeric designs with enhanced properties and functions, particularly in biology. Chitosan has been used as a fascinating biomaterial in developing different types of drug delivery techniques, as regenerative medicine in the area of health science or pharmacy. Tremendous use of agrochemicals for increasing crop production and their protection causes significant health and environmental concerns; therefore, chitosan-based nanomaterials such as nanoparticles, hydrogels, and nanocomposites have been applied in agriculture due to their unique antimicrobial and plant growth-promoting properties. These special properties endorse chitosan with promising potentialities for development in biomedicine fields like drug delivery, gene delivery, cell and molecular imaging, development of different sensors, and the treatment and diagnosis of some diseases like cancer, neurodegenerative diseases, etc. In contrast to the native chitosan, the chitosan-based nanomaterials are known to exhibit improved chemical, mechanical, and physical properties like higher surface area, tensile strength, porosity, conductivity, photo-luminescence, etc. This chapter focuses on the current research aspects of chitosan-based nanomaterials by highlighting their properties and potentialities in different domains. � 2022 Elsevier Inc. All rights reserved.
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    Structural transformation, magnetization reversal and magnetic switching in Cr doped GdMnO3perovskite
    (Royal Society of Chemistry, 2021) Tiwari, Priyanka; Yadav, Manish; Bastia, Aiswarjya; Pandey, G.C.; Rath, Chandana
    In this paper, the effect of Cr doping on the structure and magnetic properties of a GdMnO3 (GMO) perovskite is reported. The X-ray diffraction (XRD) patterns show a structural transformation from O? to O type orthorhombic symmetry after doping 50 at% Cr into GdMnO3 (GMCO), which is confirmed by the Rietveld refinement fitting. Furthermore, the Jahn-Teller distortion (J-T) factor estimated from XRD is found to decrease, and this agrees well with the value estimated from X-ray absorption fine structure (EXAFS) studies. The temperature-dependent magnetization shows an enhancement in N�el temperature (TN) from ?42 K in GMO to ?140 K together with magnetization reversal (MR) and a spin reorientation transition (TSR) in GMCO. At 15 K, magnetic switching behavior is discovered upon varying the applied magnetic field from 500 to 2000 Oe. Such unusual magnetic behavior is explained on the basis of magnetic interactions between Gd3+, Mn3+, and Cr3+ ions. The structural and magnetic properties of these perovskites have made possible more applications relating to magnetic switching and spintronic devices. � The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
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    Synthesis and structural studies of Cu(i) methylthiosalicylate complexes and their catalytic application in thiol-yne click reaction
    (Royal Society of Chemistry, 2022) Kumar, Krishna; Tiwari, Priyanka; Kant, Rajni; Bhattacharya, Subrato
    Three complexes of Cu(i), [Cu(PPh3)2(mts)] (1), [Cu(dppf)(mts)] (2) and [Cu(dppe)(mts)]2 (3) (mts = methylthiosalicylate; dppf = diphenylphosphinoferrocene; dppe = diphenylphosphinoethane), have been synthesized and characterized. Complexes 1 and 2 are monomeric, while 3 has a dimeric structure. The coordination geometry around Cu(i) in these complexes are trigonal pyramidal/distorted tetrahedral. The catalytic activities of the complexes towards hydrothiolation of alkynes (via thiol-yne click reaction) have been studied. Out of these three complexes, 2 has been found to be an efficient catalyst for the synthesis of unsymmetrical vinyl sulfide. The desired vinyl sulfides are obtained in good to excellent yields, with up to >99% Z stereoselectivity in one case. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives. The scope and versatility of the method have been successfully demonstrated with a few examples. � 2022 The Royal Society of Chemistry.