Three organic−inorganic hybrid chlorides based on pyrazine-bridged bisimidazoly cation: crystal structures, luminescent sensor and photoelectric properties

Organic−inorganic hybrid halides have attracted great attention because of their outstanding photoelectric properties. Using appropriate organic and inorganic metal halide components, organic−inorganic hybrid halides with controlled dimensionalities at the molecular level can be obtained. In this study, three new hybrid chlorides, [H₂bimpz]₀.₅[PbCl₃] (1), [H₂bimpz][BiCl₅] (2) and [H₂bimpz][SbCl₅] (3) [2,5-bis(N-imidazolyl)-pyazine, bimpz], were synthesized and crystallographically characterized. Compound 1 consists of a one-dimensional chain structured by tetragonal [PbCl₅]^3- units. Compound 2 features a binuclear [Bi₂Cl₁₀]^4- cluster linked by two [BiCl₅]^2- through edge-sharing. Compound 3 exhibits a distorted five-coordinated mononuclear [SbCl₅]^2- anion. Both 1 and 3 exhibit a trans-conformation in [H₂bimpz]²⁺ while 2 adopts a cis-conformation. 1 presents a band gap of 3.28 eV, while both 2 and 3 show energy band gap of approximately 3.09 eV. 3 displays the potential as a luminescent sensor for Cr₂O₇²⁻ ions with a limit of detection 1.52 × 10⁻⁸ M. Moreover, the photocurrent response follows the order: 3 > 1 ≫ 2, which demonstrates the photoelectric properties are attributed to the synergistic effect of the short interactions between anions and cations and π‧‧‧π interactions.