Abstract
Two new coordination polymers [Cu(5-NIP)(2)(TBPE)] (1) (where, 5-NIP = 5-nitro isophthalic acid and TBPE = trans-4,4'-bipyridylethylene) and [Zn-4(mu(3)-OH)(2)(5-NIP)(4)(TBPE)(2)] (2) have been synthesized and structurally characterized. Compound 1 features a molecular ladder type structure composed of Cu-2(5-NIP)(4) as metallacyclic platforms and TBPE as building blocks. Two nearly parallel ladders are assembled through interactions between benzene rings of 5-NIP molecules, whereas a supramolecular two-fold interpenetrated square grid network results from the hydrogen bonding interactions between free carboxylates and nitrates of the 5-NIP molecules. Compound 2 forms a 3D network which is constructed from tetrameric units composed of two tetrahedral and two octahedral Zn(II) centers arranged in a coplanar fashion by two triply bridging mu(3)-OH groups. The electronic spectra of compound 1 reflect the distorted octahedral symmetry around the copper center in corroboration with the crystal structure data. EPR measurements again reconcile the D-4h symmetry for copper in an axially elongated octahedral geometry, in agreement with the spectroscopic studies. Magnetic susceptibility measurement reveals that compound 1 behaves like a magnetically dilute system with large spin-orbit coupling and it exhibits weak antiferromagnetic coupling at lower temperatures. Furthermore, the luminescent properties of both compounds were also determined in the solid state at room temperature. (C) 2011 Elsevier Ltd. All rights reserved.