Syntheses, crystal structures and photocatalytic properties of four hybrid iodoargentates with zero- and two-dimensional structures

With a [TM(phen)3]2+ (TM = transition metal, phen = 1,10-phenanthroline) complex and N-alkylated [(Me)2-2,2′-bipy]2+ (Me = methyl, 2,2′-bipy = 2,2′-bipyridine) as cations, a series of hybrid iodoargentates, namely [TM(phen)3]2Ag3I7 (TM = Mn (1), Fe (2)), [Mn(phen)3]Ag5I7 (3) and [(Me)2-2,2′-bipy]2Ag7I11 (4), have been solvothermally prepared and structurally characterized. Compounds 1 and 2 feature isolated windmill-shaped [Ag3I7]4− trimers based on [AgI3] triangles, whereas compound 3 contains two-dimensional (2D) microporous [Ag5I7]2− layers composed of [Ag3I7] and [Ag7I13] secondary building units (SBUs) based on [AgI4] tetrahedra. In compound 4, a 2D [Ag7I11]4− slab is formed by alternating interconnection of two different types of [Ag7I12] double chains via corner-sharing with one-dimensional (1D) large channels occupied by [(Me)2-2,2′-bipy]2+ cations. UV-vis diffuse-reflectance measurements reveal that the title compounds possess semiconducting behaviors with smaller band gaps of 1.85, 1.78, 1.89 and 2.03 eV, respectively. Sample 4 shows highly efficient photocatalytic degradation activity over organic pollutants than N-doped TiO2 (P25) under visible light irradiation. Moreover, a possible mechanism for the stable photocatalytic activity is proposed based on band structure calculation. Finally, the luminescence properties and thermal stabilities of the title compounds are also studied.