Syntheses, structures and magnetism of two Cu(II) coordination polymers of d-camphorate controlled by metal-ligand ratio

Abstract

By controlling the metal-ligand ratios, two new Cu(II) coordination polymers based on d-camphoric acid (H2DCA) and 1,4-bis(imidazol-1-yl)-butane (bimb), {[Cu2(DCA)2(bimb)2(H2O)]2·7H2O}n (1), and {[Cu2(DCA)2(bimb)]}n (2), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, IR and UV–Vis spectra, powder X-ray diffraction. Comparative investigation showed that the different metal-ligand ratios affected the coordination modes of ligand and thus resulted in two distinct structures from 1D chain to 3D network. In 1, the Cu(II) centers are connected by DCA2− and bimb into 1D chains, and (H2O)4 water clusters connect the 1D chains into a 3D supramolecular structure via OH⋯O hydrogen bonds. Differently, the Cu(II) centers in 2 are bridged by four carboxyl of DCA2− to form the binuclear paddle-wheel [Cu2(O2CR)4] units, which are pillared by bimb ligands into a 3D framework showing 6-connected pcu topology. Moreover, thermogravimetric and magnetic properties of the two CPs have also been investigated.