A series of Keggin-based compounds constructed by conjugate ring-rich pyrazine and quinoxaline derivatives†
Abstract
Through the use of conjugate ring-rich pyrazine and quinoxaline derivatives, five new Keggin polymolybdate based compounds, [AgI3L12(H2O)2(PMo12O40)] (1), [AgI4L15(SiMo12O40)] (2), [AgI6L26(PMo12O40)2] (3), [AgI2L22(C16H36N)2](SiMo12O40)] (4), [CuI3L23(PMo12O40)] (5) (L1 = 2,3-diphenylpyrazine, L2 = 2,3-diphenylquinoxaline, C16H36N = tetrabutylammonium), were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction. In compound 1, three AgI ions are fused by two L1 molecules to form a [Ag3L12]3+ subunit, and these subunits link the PMo12 anions to construct two kinds of 1D chains (I and II). Chains I and II connect to each other by sharing the same PMo12 anions and a 2D grid-like layer is built. The asymmetric unit of compound 2 is linked to form a dimer by sharing Ag ions, and a 1D double strand is formed. The SiMo12 anions connect adjacent 1D double strands through Ag3–O23 bonds and a 2D network is built. In compound 3, there exists a 1D ladder-like double chain with PMo12 anions as linking bars. A 2D layer is formed by linkage Ag2–O24 between adjacent chains. In compound 4, the PMo12 anions act as inorganic linkages to connect adjacent zigzag chains through Ag1–O3 bonds to construct a 2D grid-like layer. In compound 5 two CuI–L2 lines are fused by PMo12 anions to build a 1D ladder-like chain. Additionally, the electrochemical and photocatalytic properties of the title compounds have been studied.