Syntheses, structures and fluorescent properties of cadmium coordination polymers based on 2,3′,5,5′-biphenyl tetracarboxylate and N-donor ancillary ligands

Self-assembly of cadmium(II) salt based on 2,3',5,5'-biphenyl tetracarboxylate with or without various N-donor ligands affords a series of coordination polymers, namely {[Cd-1.5(Hbptc)(H2O)(4.5)]center dot 2H(2)O}(n) (1), {[Cd-2(bptc)(2,2'-bipy)(2)]center dot 2H(2)O}(n) (2), {[Cd-2(bptc)(pyp)(2)(H2O)(2)]}(n) (3), [Cd(H(3)bptc)(2)(bip)(2)](n) (4), and {[Cd-2(bptc)(bpt)(H2O)]center dot H2O}(n) (5), where H(4)bptc = 2,3',5,5'-biphenyl tetracarboxylic acid, 2,2'-bipy = 2,2'-bipyridine, pyp = 3-(pyrid-2-yl)pyrazole, bip = 3,5-bis(1-imidazol)pyridine, bpt = 3,5-bis(4-pyridyl)-1,2, 4-triazolyl. Their structures were determined by single-crystal X-ray diffraction analysis and further characterized by elemental analysis and IR spectra. Complex 1 shows a 2D helical layer, which is further extended to a 3D supermolecule network through inter-layer C-H center dot center dot center dot O hydrogen bonds and pi center dot center dot center dot pi stacking interactions. Complex 2 exhibits a (3,6)-connected (4(3))(2)(4(6).6(6).8(3))-kgd topology. Complex 3 possesses a 2D (3,5)-connected (4.5.6)(4.5(3).6(4).7(2)) net based on 1D tube-like chains. Complex 4 has a 1D polymeric ribbon containing left- and right-handed helical chains, which are further hydrogen bonded to form a 2D supermolecule layer. Complex 5 possesses a 3D (4,5,7)-connected framework. Moreover, the fluorescent properties of 1-5 in the solid state have been investigated. (C) 2014 Elsevier Ltd. All rights reserved.