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.

Graphical abstractThree 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 is a novel mixed-valence copper(I,II) complex. The syntheses are sensitive to the experimental controls. Our results offer the possibility to get completely different topological structures by varying hydrothermal reactional conditions even when the same starting materials are used.Figure optionsDownload full-size imageDownload as PowerPoint slide