Exploring structure, molecular interactions, optical and thermal properties of Bis(2-Aminopyrimidinium) selenate monohydrate: A combined experimental and theoretical study

Single crystals of bis(2-aminopyrimidinium)selenate monohydrate were obtained by slow evaporation at ambient temperature from a dilute solution of selenic acid mixed with a hot aqueous solution of 2-aminopyrimidine in a molar ratio of 1:2. Analysis via single-crystal X-ray diffraction confirmed the compound's crystallization within the monoclinic system, specifically in the centrosymmetric space group P21/c. 1 /c . The lattice parameters were determined as a = 14.160(3) & Aring;, b = 6.6870(13) & Aring;, c = 14.274(3) & Aring;, beta = 91.25(3)degrees degrees and V = 1351.3(5) & Aring;3. 3 . The vibrational spectra were examined by employing quantum chemical density functional theory (DFT) calculations utilizing the B3LYP-6-311++G (d, p) basis set, and the results were compared between experimental and calculated values. DFT computations were utilized to assess vibrational frequencies and electronic characteristics. Confirmation of charge transfers and strong inter- and intramolecular interactions was achieved via frontier molecular orbital analysis and Natural Bond Orbital analysis. The chemical structure of the title compound was established by analyzing its 1 H NMR and 13 C NMR spectra. Computational methods were exploited for ground state structure determination and HOMO-LUMO calculations were determined. Experimental and theoretical Ultraviolet-Visible region spectra, including optical emission in the photoluminescence spectrum, were comparable. Insights into intermolecular interactions were gained through three-dimensional Hirshfeld surface analysis and 2D fingerprint maps. Additionally, DSC analysis quantified heat flow concerning temperature.