Prospective light-harvesting material of L-phenylalaninium selenate monohydrate: Synthesis, thermal behavior, vibrational and optical properties

Abstract

The present work focuses on the study of a new organo-selenate hybrid material, namely [C9H12NO2]2SeO4.H2O, abbreviated as (LPA)2.SeO4.H2O, which was successfully obtained at room temperature by slow evaporation. The structure was studied by the X-ray single-crystal diffraction process. This compound crystallizes in the monoclinic system, with a non-centrosymmetric P21 space group and the following lattice parameters: a = 12.817(3) Å; b = 6.272(15) Å; c = 13.629(3) Å, β=103.847(7)°, Z = 2 and V = 1063.7(4) Å3. The atomic arrangement in the structure is described as an alternation of organic and inorganic entities along the a-axis. The IR and Raman spectra were recorded in the 500–4000 cm-1 and 10–4000 cm-1 frequency region, respectively, confirming the existence of vibrational modes that correlate with organic and inorganic groups. The crystal arrangement is determined by hydrogen bonds of the type NH…O, OH…O and OW-H…O. The intermolecular interactions in the crystal structure were quantified and analyzed using Hirshfeld surface analysis. TGA-DTG and DSC analyses have shown that compound dehydration at around 90°C produces an anhydrous compound that is thermically stable until 122°C. Experimental UV–Visible absorption of the compound demonstrated its semiconducting properties, revealing a direct optical band gap at 5.53 eV. Finally, photoluminescence measurements indicate that the synthesized material exhibits solid-state luminescence properties. Optimized geometry and HOMO-LUMO were calculated using the B3LYP/6–311+ G(dd,p) basis set. The theoretical calculations performed by density functional theory are in agreement with the experimental results obtained.