Inorganic-acid-induced structures of cobalt(II) and copper(II) complexes based on 2,4,5-tri(4-pyridyl)-imidazole ligand

Four complexes based on 2,4,5-tri(4-pyridyl)-imidazole (Htpim), such as [Co(Htpim)2(SO4)(H2O)]n (1), [Co(tpim)2(H2O)2]n (2), [Cu(Htpim)2(SO4)]n (3), and [Cu2(Htpim)(tpim)(NO3)3(DMAC)]n (4), have been synthesized and characterized. Different structures, including two similar 1D linear chains in 1 and 2, a 2D 44 layer in 3, and a 2D double layer {4.62}2{42.64.82.102}{62.8} network in 4, were attributed to different kinds and quantities of inorganic acids under the reaction condition. Hereinto, inorganic acid was not only used to adjust the pH value of the reaction system, but also to act as a coordination component in 1, 3, and 4. Moreover, thermal stabilities and luminescent properties of 1–4 were also investigated.