Structural Investigation of Coordination Polymers Constructed from a Conformational Bis‐triazole Ligand and V‐Shaped Bridging Carboxylate Anions: Hydrothermal Syntheses, Crystal Structures, and Property Studies

The conformational bis-triazole ligand 4,4'-bis[(1,2,4-triazol-1-yl)methyl]biphenyl (btmb, 1), was successfully synthesized, and seven new coordination polymers, namely {M(oba)-(btmb)} n [M = Cd 2+ (2), Co 2+ (3), Ni 2+ (4), and Zn 2+ (5)], {M(sdba)(btmb)} n [M = Co 2+ (6) and Cd 2+ (7)], and {[Cu(H 2 odpa)(btmb)(H2O)]·2H20} n (8), (H 2 oba = 4,4'-oxydibenzoic acid, H 2 sdba = 4,4'-sulfonyldibenzoic acid, and H 4 odpa = 4,4'-oxydiphthalic acid), have been synthesized by utilizing the btmb ligand and the polymers have been characterized in detail. Complexes 2-4 are isostructural exhibiting 2D-layer structures and can be described as (3,4)-connected networks with (4 2 .6 3 .8)(4 2 .6) topological notation. Complex 5 shows 2D layers with left- and right-handed helical chains and has a (3,4)-connected net with (4.5 2 )(4.5 3 .7 2 ) topology. Complexes 6 and 7 are isostructural and display 2D undulating networks with (4,4) sheets that are further packed through van der Waals interactions to generate a 3D supramolecular structure. Complex 8 also represents a 2D network with a 4 4 -sql net, which is extended into a 3D supramolecular framework by hydrogen-bonding interactions. The structural differences of these complexes demonstrate that the conformation of the btmb ligand and flexible aromatic polycarboxylate anions play critical roles in the formation of the resulting frameworks. Furthermore, their thermal properties have been studied by thermogravimetric analysis (TGA) and the TGA results reveal that the triazole-based frameworks have a high thermal stability, which suggests they are good candidates for the construction of more stable complexes. The photoluminescent properties of complexes 2, 5, and 7 have also been studied.