A new luminescent material based on bismuth(III): Synthesis, structural characterization, DFT calculations, Hirshfeld surface, thermal behavior, vibrational and optical properties

Abstract

Bismuth-halide-based hybrid materials are desirable in luminescent applications due to low toxicity and chemical stability. (C₈H₁₂N)₄Bi₂Cl₁₀, was elaborated by the slow evaporation technique at room temperature. Single-crystal X-ray diffraction analysis indicates that the compound belongs to the monoclinic crystal system with the centrosymmetric space group P2₁/c. The formula unit comprises four protonated organic cations (C₈H₁₂N)⁴⁺, one [Bi₂Cl₁₀]⁴⁻ dimer. The organic layers are inserted between the inorganic ones and connected with N-H…Cl and C-H…Cl hydrogen bonds to build a three dimensional network. The infrared IR and Raman studies which were recorded at room temperature in the 500–4000 cm⁻¹ and 50–4000 cm⁻¹ frequency regions, respectively, confirmed the existence of vibrational modes that correspond to the organic and inorganic groups. The optimized molecular structure and vibrational frequencies were calculated by the Density Functional Theory (DFT) method using the B3LYP level employing level employing a LANL2DZbasis set. It shows a good agreement between the calculated and the experimental vibrational frequencies. Hirshfeld surface analysis of close intermolecular interactions in this compound enables the identification and examination of molecular shapes. The crystal exhibits thermal stability up to 160 °C using the Thermogravimetric analysis TGA. The optical properties were characterized experimentally by UV–visible absorption studies and photoluminescence measurements. The Photoluminescence spectrum shows a green luminescence peak which is attributed to excitonic emissions within the chlorobismuthate octahedron. HOMO-LUMO orbital energies were studied by using DFT calculations.