Mrinalini Dutta Mahavidyapith

We developed a reaction–diffusion model of the Gierer–Meinhardt type to simulate the formation of orbicular patterns in granites. By coupling felsic (light-coloured) and mafic (dark-coloured) materials as the activator and inhibitor, respectively, our model reproduces a wide range of orbicular patterns, including bands and rings. A comprehensive quantitative analysis reveals that the non-equilibrium dynamics between felsic and mafic materials drive their reorganisation into matrix and core structures within the granites. Furthermore, our linear stability analysis demonstrates that the stability of the system, whether stable or oscillatory, is determined by the eigenvalues in the complex plane, providing insight into the two-component reaction–diffusion dynamics governing the felsic-mafic system. Self-organising chemical processes, driven by varying diffusion rates and nonlinear interactions between minerals during the cooling and solidification of magma, can explain the formation of concentric orbicular patterns in granitic rocks.

Microenvironment surrounding Tyrosine (Tyr) / Tryptophan (Trp) and heme appear to characterize the UV-vis absorption spectra of human hemoglobin (HHb). Structural elucidation of HHb using multiple tools, that may contribute to its spectral properties, then indicate greater structural stability of subunit A and the significance of its heme, Tyr42 and Trp14. Mutagenesis of Tyr42 and Trp14 of subunit A to Glycine (Gly) further validate their contribution in determining the structural stability, physicochemical properties, functional properties, and secondary structure of HHb. Accordingly, the use of structural coordinates of Tyr42 and heme as the first cluster and Trp14, Tyr42 and heme as the second cluster to represent the microenvironment of HHb is assessed for the first time. The calculated (DFT) absorption and FTIR properties of both the clusters are in well agreement with experimental absorption and FTIR characteristics of whole HHb suggesting prospective biomedical applications of these clusters.

The correct assignment of absolute configuration to chiral molecules is fundamental for a comprehensive understanding of their three-dimensional structures. The descriptors used for distinguishing between a pair of enantiomers are R (Rectus) and S (Sinister) based upon the Cahn-Ingold-Prelog (CIP) system. The CIP system necessitates the determination of ligand priorities attached to an sp3-stereocenter in chiral molecules, guided by an established set of rules. However, students often struggle with the practical application of these methods, especially when the lowest priority group does not point away from the observer, thus complicating the assignment of R/S descriptors. This paper introduces a student-friendly unified approach utilizing the well-known "Exchange in a Group of Three (EIGT) rule", traditionally applied to Fischer projections, to facilitate the assignment of absolute configurations across various representations, including wedge-dash, Fischer, Newman, Sawhorse, and chair conformations (for cyclohexane derivatives). The method aims to simplify the process for introductory stereochemistry students, enabling them to confidently determine CIP-based absolute configurations even when the least priority group is not optimally positioned. A student-based evaluation validated the utility of the proposed method. However, like most mnemonic-based approaches, the EIGT method may not be equally effective in all stereochemical contexts; for instance, certain complex three-dimensional arrangements (e.g., specific Newman projections) may still require additional visualization aids or supplementary instructional tools.

Metal-halide coordinated azoimidazole complex have been found to be potential functional material in the field of materials science and its related applications. In this communication, we report the photophysical and electrical properties of organized assemblies of synthesized di-iodo-Pb(II) coordinated long alkyl chain substituted azoimidazole complex namely di-iodo-Pb(II)-1-hexadecyl-2-(arylazo) imidazole abbreviated as PbI2-AAIm prepared via Langmuir-Blodgett technique. The interfacial behaviour at air-water interface and surface morphology of the organized thin film structure deposited on solid substrate are characterized by a series analytical methods such as surface pressure vs area per molecule (it-A) isotherm, hysteresis and compressibility analysis of isotherm, in-situ Brewster angle microscopy (BAM), UV-vis absorption, steady state fluorescence, Fourier transform infrared spectroscopies and atomic force microscopy (AFM) respectively. Spectroscopic studies confirm the formation of J-type molecular aggregates of PbI2-AAIm complex in the LB film deposited onto solid substrate. Compression induced aggregation of PbI2-AAIm complex in LB film is reflected as linear nanodimensional rodlike assemblies in the AFM topographical image. Cross-sectional scanning electron microscopy was used to get idea about the average thickness of LB and drop cast films. DFT study explores the electronic energy states of this metal-imidazole complex. DC current-voltage characteristics of LB film based device fabricated on ITO coated glass substrate exhibits Schottky diode like non-linear current conduction which is also found to be photo-responsive. The current-voltage (I-V) characteristics of LB film based device is also compared with that of drop casted film device of PbI2-AAIm complex. The surface morphological parameters of LB and drop cast films have been compared to discriminate the overall electrical properties of their electronic device. The as fabricated Schottky device of imidazole based metal-ligand complex may have promising potential for applications in optoelectronics and related field.