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

Abstract

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.