Pyridyl and triazole ligands directing the assembling of zinc(II) into coordination polymers with different dimensionality through azides

Abstract

Five coordination polymers catena-[(3-Hampy)2[Zn7(N3)16(3-ampy)4]·3H2O] (1), catena-[Zn2(μ2-4-HO-py)(μ1,1-N3)4]·H2O (2), catena-[Zn2(μ2-4-amtz)(μ1,1-N3)4] (3), catena-[Zn(5-Et-2-Me-py)(μ1,1-N3)2] (4) and catena-[Zn(μ2-2-O-py-N-oxide)(μ1,1-N3)] (5), where 3-ampy=3-aminopyridine, 4-HOpy=4-hydroxypyridine, 4-amtz=4-amino-4H-1,2,4-triazole, 5-Et-2-Mepy=5-ethyl-2-methylpyridine and 2-HO-py-N-oxide=2-hydroxypyridine-N-oxide were synthesized and structurally characterized by single crystal X-ray crystallography. The complexes display different dimensionality depending on the nature of the coligand. The anionic polymer in complex 1 consists of 1D system of defective dicubanes with two different azido-bridging μ1,1-N3 and μ1,1,1-N3 modes. Complexes 2 and 3 are isostructural and both exhibit 2D networks with μ(O,O)-pyridinone bridging molecule in 2 or μ(N,N′)-bridging 4-amtz in 3, and μ1,1,-azide bridging. Complex 4 reveals a zigzag chains of 1D polyhedral through a doubly bridged μ1,1-N3 bonding mode, whereas in complex 5 a 1D polymeric chain is generated via singly bridged μ1,1-N3 bonding and hydrogen bonding results in the formation of supramolecular 2D system. The emission spectral properties of the parent free ligands and their corresponding Zn(II) complexes were investigated where enhancement luminescence emissions with strong red shifts were observed in complexes 2, 4 and 5.