Investigation on the Influence of Solvents Environment on the Optoelectronic Properties of the Fluorescent Probe 1,3,4-Oxadiazole Analogues: A Combined Theoretical and Experimental Study.

This study investigates the photophysical properties of a nitrobenzene-substituted 1,3,4-oxadiazole derivative (OX-NO) using both theoretical and experimental methods. The impact of the solvent on OX-NO absorption and fluorescence spectra, as well as its fluorescence quantum yield, was initially studied. A noticeable bathochromic shift in the Stokes shift indicated a π→ π* transition within the molecules. Solute-solvent interactions were analysed using Catalan parameters, distinguishing between specific and nonspecific interactions. Excited state dipole moments were derived from Lippert's, Bakshiev's, and Chamma Viallet's equations, showing increased polarity in the excited state compared to the ground state. Ground state dipole moments were determined via solvatochromic shift methods and ab initio techniques. Additionally, detailed analyses of bond length, angles, dihedral angles, Mulliken charge distribution, and HOMO-LUMO energy gap were conducted using the DFT-B3LYP-6-311G basis set in Gaussian-09 W. The energy band gap values obtained from theoretical calculations and experimental methods (cyclic voltammetry and UV-Visible spectroscopy) exhibited excellent agreement. Reactive sites such as electrophilic and nucleophilic regions were identified through total electron density, electrostatic maps, molecular electrostatic potential, and 3D plots using DFT computational analysis. Global descriptors were employed to characterize the compounds' chemical reactivity comprehensively. The observed photophysical attributes underscore the potential of these fluorophores in various applications like organic light-emitting diodes, solar cells, and chemosensors. This study contributes crucial insights into the optoelectronic properties of nitrobenzene-substituted 1,3,4-oxadiazole derivatives, paving the way for their future integration in advanced technological domains.

Electrophysiologic study of spraymen exposed to insecticide Lambda-cyhalothrin.

Lambda-cyhalothrin ia a potent insecticide which acts by producing prolonging the duration of opening of sodium channels in neurons. While it is being used in several countries, no extensive neurophysiologic study of toxic effects in humans is available. We performed multimodality electro-physiologic studies in 15 spraymen in the age range of 19-48 years, before and after the exposure to this insecticide, with a view to detect any neurotoxic manifestation. Facial nerve conduction, blink response, repetitive stimulation test and visual, auditory and somatosensory evoked potentials were normal. Six subjects had mild changes in peripheral nerve conduction parameters. Comparison of mean values of the various nerve conduction studies in three subjects showed normal findings. We conclude that Lambda-cyhalothrin may produce transient, subclinical, electrophysiologic changes in the nerves of upper limb, possibly as a local toxic manifestation.