Fabrication of Cu(ii) based halobenzoate appended ladder polymers with efficient charge transport properties

Abstract

Two isotypical Cu(II) based one-dimensional coordination polymers (1D CPs) [{Cu₂(p-clba)₄(bpe)₂}{Cu(p-clba)₂(bpe)(CH₃OH)}]_n·1.25H₂O (1) and [{Cu₂(p-brba)₄(bpe)₂}{Cu(p-brba)₂(bpe)(CH₃OH)}]_n·1.25H₂O (2) (H₂p-clba = para-chlorobenzoic acid, H₂p-brba = para-bromobenzoic acid and bpe = 1,2-bis(4-pyridyl)ethylene) have been synthesized and characterized by X-ray structure analysis. In the solid-state structure, both the compounds undergo X⋯π (X = Cl or Br) interactions to generate two-dimensional (2D) supramolecular architectures. Here, due to the larger size and better polarisability of the Br atom, the Br⋯π interaction is stronger than the Cl⋯π interaction, which accounts for the stronger interchain interactions in 2 as compared to 1. This is depicted in the observed electrical conductivity of the compounds. Compound 2 with stronger interchain interactions shows better charge transport and hence, increased conductivity.