((1H-tetrazol-5-yl) methyl) pyridine-based metal coordination complexes: in situ tetrazole synthesis, crystal structures, luminescence properties†
Abstract
Six novel transition metal coordination complexes, [Cu(3TMP)] (1), [Zn(3TMP)Cl] (2), [Cd3(3TMP)4(N3)2]·0.38H2O (3), [Zn3(4TMP)2(OH)2(H2O)]·2(NO3) (4) and [M2(4TMP)(OH) (H2O)(SO4)] (M = Zn (5), M = Cd (6)) (3HTMP = 3-((1H-tetrazol-5-yl) methyl) pyridine; 4HTMP = 4-((1H-tetrazol-5-yl) methyl) pyridine), have been hydrothermally synthesized through in situ tetrazole synthesis. These complexes have been structurally characterized by single crystal and powder X-ray diffraction elemental analyses, Fourier transform infrared spectroscopy as well as thermal studies. Complexes 1–6 are two or three-dimensional (3D) frameworks with structural diversity owing to the versatile coordination modes of the in situ generated flexible ligands. Complex 1 presents a reticular structure consisting of two-dimensional (2D) layers formed by the linkage between the pyridine rings and [Cu–tetrazole–Cu] wave-like chains. Complex 2 features a 3D framework built up by two kinds of helical chains composed of Zn(II) and the flexible ligand 3TMP. Complex 3 exhibits a 3D framework built up from 3TMP ligands and trinuclear [Cd3(N3)2] building units. Complex 4 crystallizes as a 3D coordination complex constructed from two-dimensional layers and the linkers of 4TMP ligands, with NO3− anions situated in the channels. Complexes 5 and 6 exhibit a 3D framework constructed from {M2(4TMP)(OH)}nn− (M = Zn (5), M = Cd (6)) layers and sulfate anions. In addition, the counterions, such as the Cl terminal ligand in 2, the N3 terminal ligand in 3, the μ2-OH bridging ligand in company with free NO3− anions in 4, and the μ3-OH bridging ligand in company with free SO42− anions in 5 and 6, have decisive influence on the dimensionality and functionality of the final complexes. Furthermore, the solid state luminescence properties of these complexes have been investigated.