Diverse architectures and luminescence properties of two novel copper(i) coordination polymers assembled from 2,6-bis[3-(pyrid-4-yl)-1,2,4-triazolyl]pyridine ligands

Abstract

Two attractive Cu(I) coordination polymers with unique structures, namely, {[Cu₈(bptp)₄]·6H₂O} (1) and {[Cu₅(bptp)₂(CN)]·2H₂O} (2), have been successfully synthesized based on a V-shaped multidentate N-containing ligand 2,6-bis[3-(pyrid-4-yl)-1,2,4-triazolyl]pyridine (H₂bptp). The structural analysis reveals that complex 1 displays a Cu₈ cluster-based infinite 1D ladder chain, in which each H₂bptp ligand links four or five Cu(I) ions through nitrogen atoms of pyridine/triazole groups. Complex 2 features an unusual (3,4,5)-connected 3D topological network with the Schläfli symbol (4²·5⁴·6³·7)(4²·6³·7)(5·6·8)(5·6²·7·8²), which has not been reported before. The structural and dimensional diversity of the two complexes indicates that H₂bptp exhibits strong coordination ability and diverse coordination modes. It is worth mentioning that the Cu⋯Cu distances in 1 and 2 are shorter than the sum of the van der Waals radii of copper(I) (2.80 Å), implying the metal–metal bonding interactions. What is more, the solid-state luminescence bands of 1 and 2 have also been investigated between 298 and 10 K. Interestingly, the low-energy emission bands of 1 and 2 exhibit yellow/orange-red luminescence, and their intensities increase gradually upon cooling.