Two Types of 2D Layered Iodoargentates Based on Trimeric [Ag₃I₇] Secondary Building Units and Hexameric [Ag₆I₁₂] Ternary Building Units: Syntheses, Crystal Structures, and Efficient Visible Light Responding Photocatalytic Properties

With mixed transition-metal-complex, alkali-metal, or organic cations as structure-directing agents, a series of novel two-dimensional (2D) layered inorganic–organic hybrid iodoargentates, namely, Kx[TM­(2,2-bipy)3]2­Ag6I11 (TM = Mn (1), Fe (2), Co (3), Ni (4), Zn (5); x = 0.89–1) and [(Ni­(2,2-bipy)3]­[H-2,2-bipy]­Ag3I6 (6), have been solvothermally synthesized and structurally characterized. All the title compounds feature 2D microporous layers composed by [Ag3I7] secondary building units based on AgI4 tetrahedra. Differently, the [Ag3I7] trimers are directly interconnected via corner-sharing to form the 2D [Ag6I11]5– layer in compounds 1–5, whereas two neighboring [Ag3I7] trimers are initially condensed into a hexameric [Ag6I12] ternary building unit as a new node, which further self-assembles, leading to the 2D [Ag6I10]4– layer in compound 6. The UV–vis diffuse-reflectance measurements reveal that all the compounds possess proper semiconductor behaviors with tunable band gaps of 1.66–2.75 eV, which lead to highly efficient photocatalytic degradation activities over organic pollutants under visible light irradiation compared to that of N-dotted P25. Interestingly, all the samples feature distinct photodegradative speeds at the same reaction conditions, and compound 1 features the highest photocatalytic activity among the title phases. The luminescence properties, band structures, and thermal stabilities were also studied.以混合过渡金属配合物、碱金属或有机阳离子作为结构导向剂（structure-directing agents），一系列新型二维（2D）层状无机-有机杂化碘化银盐经溶剂热法合成并完成结构表征，其通式为Kₓ[TM(2,2'-联吡啶)₃]₂Ag₆I₁₁（TM = 锰(1)、铁(2)、钴(3)、镍(4)、锌(5)；x = 0.89~1）以及[Ni(2,2'-联吡啶)₃][H-2,2'-联吡啶]Ag₃I₆（6）。所有标题化合物均呈现由以AgI₄四面体为基础的[Ag₃I₇]次级结构单元（secondary building unit）所构筑的二维微孔层。具体而言，化合物1~5中的[Ag₃I₇]三聚体通过共用角直接相互连接，形成二维[Ag₆I₁₁]⁵⁻层；而化合物6中，两个相邻的[Ag₃I₇]三聚体首先缩合形成六聚体[Ag₆I₁₂]三元结构单元作为新的构筑节点，该单元进一步自组装，最终得到二维[Ag₆I₁₀]⁴⁻层。紫外-可见漫反射光谱测试显示，所有化合物均具备典型的半导体特性，带隙可调范围为1.66~2.75 eV；相较于氮掺杂P25（原文N-dotted P25应为笔误，按通用化学术语修正为氮掺杂P25），其在可见光照射下对有机污染物展现出高效的光催化降解活性。值得注意的是，在相同反应条件下，所有样品的光降解速率存在显著差异，其中化合物1的光催化活性在所有标题化合物中最高。本研究还对其发光性能、能带结构与热稳定性进行了系统探究。