Synthesis, structural-spectral characterization and density functional theoretical studies of pyridine-4-carbohydrazide bis(4-hydroxynitrobenzene)

A DFT study on the structure activity relationship of the natural xanthotoxin-based pharmaceutical cocrystals

In this work, the pharmaceutical cocrystals xanthotoxin-para-aminobenzoic acid (XT-PABA) and xanthotoxin-oxalic acid (XT-OA) were systematically investigated in the gas and water phases by using the quantum chemical approach. The weak intermolecular interactions have been estimated and the O1…H4 (O1…H5) intermolecular hydrogen bond (IHB) with moderate intensity and partial covalent natures was confirmed based on the computed structural parameters, topology analysis, and reduced density gradient (RDG) isosurfaces. The electrophilic and nucleophilic reactivities of different positions associated with intermolecular interactions in XT, PABA, and OA were predicted by plotting the molecular electrostatic potential (MESP) diagrams. The calculated natural bond orbital (NBO) population analysis has quantitatively unveiled the intrinsic reason for the variations in weak intermolecular interactions within XT-PABA and XT-OA cocrystals, from the gas phase to the water phase. Besides, the frontier molecular orbitals (FMOs), Fukui function, and various global reactivity descriptors were computed to measure the chemical reactivity of all the investigated molecular systems. The XT-PABA and XT-OA cocrystals explored in this work could be regarded as valuable exemplar systems to design and synthesize the high-efficiency pharmaceutical cocrystals in the experiment.

Vibrational Characterization and Molecular Electronic Investigations of 2-acetyl-5-methylfuran using FT-IR, FT-Raman, UV-VIS, NMR, and DFT Methods

Spectroscopic (FT-IR, FT-Raman, UV-vis, and NMR) techniques have been extensively used for structural elucidation of compounds along with the study of geometrical and vibrational properties. Herein, 2-acetyl-5-methylfuran, a derivative of furan, was experimentally characterized and analyzed in details using FT-IR, FT-Raman, UV-vis, and ¹H NMR spectroscopic techniques conducted in different solvents. The experimentally analyzed spectral results were carefully compared with theoretical values obtained using density functional theory (DFT) calculations at the B3LYP/6-311 + + G (d, p) method to support, validate, and provide more insights on the structural characterizations of the titled compound. The correlated experimental and theoretical structural vibrational assignments along with their potential energy distributions (PEDs) and all the spectroscopic spectral investigations of the titled structure were observed to be in good agreements with calculated results.