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)](2)Ag3I7 (TM = Mn (1), Fe (2)), [Mn(phen)(3)]Ag5I7 (3) and [(Me)(2)-2,2'-bipy](2)Ag7I11 (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.