Showing papers by "Hirdyesh Mishra published in 2019"

In Situ Functionalized Fluorescent WS 2 ‑QDsas Sensitive and Selective Probe for Fe 3+ and a DetailedStudy of Its Fluorescence Quenching

Abstract: Most of the reports suggest that liquid exfoliated WS2-QDs are unstable; therefore the need of present day is to develop a novel synthesis route for producing long-term stable WS2-QDs. Herein, we report a bottom-up single-step hydrothermal growth of in situ functionalized blue fluorescent WS2-QDs with stable fluorescence in aqueous media without subsequent treatments. Presence of various functional groups over the surface of f-WS2-QDs provides high solubility and stability to f-WS2-QDs in aqueous media preserving its fluorescence. Further, photoluminescence property of f-WS2-QDs has been employed to devise an optical sensor with a high sensitivity (KD ∼ 104 M–1) and selectivity for ferric (Fe3+) ions. Under the optimal condition, response of the sensor is found to be linear in the range of 0–55 μM with a limit of detection (LOD) of 1.32 μM, which is within the maximum permissible level of Fe3+ (∼5.4 μM) in human drinking water by the USEPA. Further, we have also carried out a detailed evaluation on fluore...

Examining pharmacodynamic and pharmacokinetic properties of eleven analogues of saquinavir for HIV protease inhibition

Abstract: HIV is one of the most lethal viral diseases in the human population. Patients often suffer from drug resistance, which hampers HIV therapy. Eleven different structural analogues of saquinavir (SQV), designed using ChemSketch™ and named S1 through S11, were compared with SQV with respect to their pharmacodynamic and pharmacokinetic properties. Pharmacokinetic predictions were carried out using AutoDock, and molecular docking between macromolecule HIV protease (PDB ID: 3IXO) and analogues S1 – S11 as ligands was performed. Analogues S1, S3, S4, S9 and S11 had lower binding scores when compared with saquinavir, whereas that of analogue S5 was similar. Pharmacokinetic predictions made using ACDilab2, including the Lipinski profile, general physical features, absorption, distribution, metabolism and excretion parameters, and toxicity values, for the eleven analogues and SQV suggested that S1 and S5 are pharmacodynamically and pharmacokinetically robust molecules that could be developed and established as lead molecules after in vitro and in vivo studies.

Excited-State Dynamics of Quinine Sulfate and Its Di-Cation Doped in Polyvinyl Alcohol Thin Films Near Silver Nanostructure Islands.

Abstract: The present study demonstrates the near-field effect of silver nanostructure island films (SNIFs) on the photophysics and exited-state dynamics of quinine sulphate (QS) and its di-cation (QSD), dop...

Electronic Structure Explanation for the Structure and Reactivity of di-n-Butyltin(IV) Derivative of Glycylphenylalanine

Abstract: The density functional theory (DFT)-based quantum-chemical calculations have been performed on di-n-butyltin(IV) derivative of glycylphenylalanine (H2L) using the Gaussian 09 software package. The molecular geometry of n-Bu2SnL was optimized at B3LYP/6-31G(d,p)/LANL2DZ(Sn) level of theory without any symmetry constraint. The harmonic vibrational frequencies were computed at the same level of theory to find the true potential energy surface (PES) minima. The various geometrical and thermochemical parameters for the studied complex are obtained in the gas phase. The atomic charges at all the atoms were calculated using Mulliken Population Analysis, Hirshfeld Population Analysis and Natural Population Analysis. The charge distribution within the studied complex is explained on the basis of molecular electrostatic potential maps, the frontier molecular orbital analysis and conceptual-DFT-based reactivity (global as well as local) descriptors, using the finite difference approximation method. The nature of O–Sn, N–Sn, N → Sn and C–Sn bonds is discussed in terms of the conceptual-DFT-based reactivity descriptors. The structural analysis of the studied complex has been carried out in terms of the selected bond lengths and bond angles. The structural and atomic charge analysis suggests a distorted trigonal bipyramidal arrangement consisting of negatively charged centres around the positively charged central Sn atom.

An Atoms-in-Molecules Theory Interpretation for the Structure of Di- n -Butyltin(IV) Derivative of Glycylvaline

Abstract: The topological and energetic properties of the electron density distribution ρ $$ (\vec{r}) $$ for the tin–ligand interaction in n-Bu2SnL, the geometric configuration of which was optimized at B3LYP/6-31G(d,p)/LANL2DZ(Sn) level of theory, have been theoretically calculated at the bonds around the central Sn atom in terms of atoms-in-molecules (AIM) theory using AIMAll (Version 16.01.09, standard). In n-Bu2SnL, the formation of a (3, − 1) critical point in the internuclear region between tin atom and bonded/coordinated atoms provided an evidence of a bonding interatomic interaction, and calculated bond path angles indicated a distorted trigonal bipyramidal geometry. The calculated topological and energetic parameters suggested a weak closed-shell interaction in all the bonded/coordinated bonds to Sn atom. This interaction possessed covalent character in Sn–Npeptide, Sn–Cα and Sn–Cα′, whereas an electrostatic interaction was observed in Sn–Namino and Sn–Ocarboxyl bonds. The calculated atomic charges suggested negatively charged centers around the central Sn atom.