A new multifunctional one-dimensional bromo-bismuthate(iii): synthesis, structural features, characterization, and optical properties of (C10H13N4)[BiBr4]·2H2O.

A new one-dimensional bromobismuthate(iii) organic-inorganic hybrid (C10H13N4)[BiBr4]·2H2O, was successfully synthesized and comprehensively investigated to elucidate its structural, thermal, and optoelectronic characteristics. Single-crystal X-ray diffraction established a monoclinic system (P21/n) with one-dimensional [BiBr4] n n- chains composed of edge-sharing BiBr6 octahedra, stabilized through an extended network of hydrogen bonding and π-π stacking interactions. Vibrational spectroscopy (FTIR and Raman) confirmed the coexistence and coupling of organic-inorganic subunits, while thermogravimetric analysis demonstrated excellent stability up to 275 °C, underscoring its robustness for high-temperature applications. Optical studies combining UV-vis, diffuse reflectance spectroscopy (DRS), and steady-state photoluminescence (PL) revealed a broad emission centered near 400 nm and an indirect band gap (E g = 2.57 eV), as supported by TD-DFT calculations. These results confirm the compound's semiconducting behavior governed by the strong spin-orbit coupling of Bi(iii), which induces band splitting and phonon-assisted transitions. The CIE 1976 chromaticity analysis located the emission within the blue-violet region (u' = 0.1725, v' = 0.2513), indicating high color purity and strong luminescence. This integrated experimental-theoretical approach demonstrates that (C10H13N4)[BiBr4]·2H2O is a stable, wide-band-gap, indirect semiconductor with promising potential for blue-emitting optoelectronic, photonic, and photovoltaic applications.