In Situ Ligand Modification Strategy for the Construction of One‑, Two‑, and Three-Dimensional Heterometallic Iodides

Three heterometallic iodides featuring the novel in situ modified ligands N,N′,N″-trimethyl-2,4,6-tris­(4-pyridyl)-1,3,5-triazine (Me3tpt3+), N,N′-dimethyl-2,4,6-tris­(4-pyridyl)-1,3,5-triazine (Me2tpt2+), and N-monomethyl-2,4,6-tris­(4-pyridyl)-1,3,5-triazine (Metpt+), [Pb3CuI10(Me3tpt)] (1), [Pb5Cu2I16(Me2tpt)2] (2), and [Pb3Cu6I14(Metpt)2] (3), were synthesized. Compound 1 exhibits a chain structure, in which the Pb4I16 units are connected by the CuI3 units. The negative charge of the resulting chain is balanced by the cationic Me3tpt3+ groups. 2 features a layer structure, in which the Pb–I chains are connected by the dimeric Cu2 units. The anionic layer is decorated by the Me2tpt2+ motifs via coordinating to the intralayer Cu­(I) ions. 3 displays a 3D framework structure, in which the inorganic layer with an 18-membered ring is composed of the strictly alternating arrangements of trimeric Pb3 units and hexameric Cu6 units. The adjacent inorganic layer is further connected by a Metpt+ linker to form the final 3D hybrid framework. It is notable that the in situ N-methylation reaction for tpt has taken place and the resultant motif (Me3tpt3+ for 1, Me2tpt2+ for 2, and Metpt+ for 3) is captured within the corresponding structure. More importantly, the structural diversities from low-dimensional chain and layer to high-dimensional framework is accomplished via the (partial) N-methylation of tripyridine motifs in the heterometallic iodide systems. Our studies offer a new coordination mode of tripyridine motif (N-coordination together with N-methylation) and provide a general strategy to integrate the polypyridine motifs and heterometallic halide systems to generate intriguing hybrid structure and investigate the potential structure-related properties. The UV–vis spectra show that the band gaps for 1–3 are 1.48, 1.35, and 1.34 eV, respectively. Their thermal stabilities have also been studied.