Self-assembly of four supramolecular architectures: From 0-D to 2-D frameworks based on an unsymmetrical N-heterocyclic ligand

The computed results of the free bmt ligand reveal that the Mulliken charges of N18 and N23 are −0.391 and −0.275, respectively, and both of them have higher distributions in the highest occupied molecular orbital (HOMO) of the free ligand bmt. Based on the above results, four new complexes, [Cu(bmt)4] · (Cl)2 · 4H2O (1), [Cu(bmt)2(NCS)2] (2), [Cu(bmt)Cl]n (3), and [Ag(bmt)(NO3)]n (4) [bmt = 1-((benzotriazol-1-yl)methyl)-1-H-1,2,4-triazole], have been synthesized and characterized by single-crystal X-ray diffraction. Complex 1 reveals a 0-D structure and further forms a 1-D supramolecular structure by intermolecular π–π interactions. Complex 2 also displays a 0-D structure, but it extends to 2-D supramolecular networks through weak Cu⋯S interactions. However, complex 3 features a 1-D wavy chain structure bearing weak Cu⋯Cl interactions to form 2-D networks. Complex 4 exhibits a 2-D netlike structure. The experimental results display that the coordination modes of the ligand bmt are corresponded with the computed results. Furthermore, the fluorescence emissions of complexes 3 and 4 in a solid state at room temperature may be assigned to ligand-to-metal charge-transfer (LMCT).

Graphical abstract[Cu(bmt)4] · (Cl)2 · 4H2O (0-D), [Cu(bmt)2(NCS)2] (0-D), [Cu(bmt)Cl]n (1-D) and [Ag(bmt)(NO3)]n (2-D) have been synthesized and characterized by single-crystal X-ray diffraction and fluorescence spectra.Figure optionsDownload full-size imageDownload as PowerPoint slide