Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers

Three new copper complexes, [CuIICuI(ip)(ipH)(4,4′-bipy)3/2]n (1), [Cu(ip)(4,4′-bipy)]n · 3nH2O (2), and [Cu(ipH)2(4,4′-bipy)]n (3), have been hydrothermally synthesized by the reaction of Cu(NO3)2 · 3H2O with isophthalic acid (ipH2) and 4,4′-bipyridine (4,4′-bipy) under different reaction conditions. Complex 1, a mixed-valence copper(I,II) complex, exhibits a 2-D interpenetrating grid framework, in which five-coordinated CuII and three-coordinated CuI environments are established. The oxidation states of center Cu atoms have been confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectra (EPR). Complex 2 features a 2-D box-like bilayer architecture, in which CuII atoms are linked by ip ligands to form a 1-D double-chain and the resulting chains are further strutted by the 4,4′-bipy ligands. In complex 3, two bridging 4,4′-bipy ligands and two terminal ipH ligands confine the CuII center in a square plane coordination geometry. The whole molecule of 3 was arranged into a 1-D linear chain structure. Additionally, the thermogravimetric analyses (TGA) for complexes 1–3 are also discussed in this paper.