Amperometric sensing and photocatalytic properties under sunlight irradiation of a series of Keggin-Ag-I compounds through tuning single and mixed ligands

摘要

By using a single conjugate ring-rich ligand L-a or L-b and mixed ligands L-a/L-b, eight Keggin-Ag-I-based compounds, namely [Ag4L5a(SiW12O40)]28H(2)O (1), [Ag3L4a(PW12O40)] (2), [Ag3L2a(H2O)(PW12O40)] (3), [Ag4L4b(SiW12O40)] (4), [Ag3KL4b(SiW12O40)]boldH/bold2O (5), [Ag6L6b(PMo12O40)(2)] (6), [(Ag4LL3b)-L-a(C14H10O2)(SiW12O40)]8H(2)O (7) and [(Ag4L2L4b)-L-a(GeMo12O40)] (8) (L-a = 2,3-diphenylpyrazine, L-b = 2,3-diphenylquinoxaline, C14H10O2 = 1,2-diphenyl-ethane-1,2-dione), were successfully synthesized by controlling the reaction parameters and well established by single-crystal X-ray diffraction, elemental analyses, and IR spectra. Compounds 1-3 are based on the L-a ligand, while 4-6 are based on L-b. The mixed L-a/L-b ligands induce the formation of 7 and 8. In compound 1, the linear [Ag4L4a](4+) subunits link SiW12 anions to form a chain. Two adjacent chains connect each other through POM anion bonds and a screw-like double track is built. Compound 2 is composed of 1D leaf-like Ag-I-L-a chains, which are further linked by anions to build a 2D grid-like layer. Compound 3 was obtained under the same conditions as 2 except at a different temperature. In 3, the inorganic double chains are connected by linear metal-organic clusters [Ag3L2a](3+) and a 2D layer is formed. Compounds 4 and 5 were also obtained at different temperatures. In 4, the adjacent grid-like layers share the same Ag ions to construct a 3D framework. Compound 5 is composed of 1D cycle-connecting-cycle chains, which are further linked by anions and Ag ions to build a 3D structure. Compound 6 is a 3D framework, with dissociative anions accommodated in it. Compounds 7 and 8 are composed of mixed organic ligands L-a and L-b. Compound 7 has two kinds of chains, which are linked by anions to form a ladder. Compound 8 contains discrete anions and [(Ag2LL2b)-L-a](2+) units. The title compound modified CPEs can act as amperometric sensors for detecting hydrogen peroxide, potassium bromate and potassium nitrite. Compounds 1-8 have excellent photocatalytic capacity for degradation of organic dyes MB and RhB under the sunlight irradiation.