Synthesis, characterization and exploration of supramolecular interactions of a Cu(II) based 1D zig-zag coordination polymer: X-ray structure determination and DFT study

Abstract

A novel Cu(II) based one-dimensional (1D) zig-zag coordination polymer (CP) formulated as [Cu(muco)(4,4′-Me2bpy)(H2O)]·2H2O (1; H2muco = trans, trans-1,3-butadiene-1,4-dicarboxylic acid or trans, trans-muconic acid and 4,4′-Me2bpy = 4,4′-dimethyl-2,2′-bipyridine) was synthesized in a self-assembly reaction using slow evaporation technique. Single crystal X-ray analysis reveals that the compound 1 crystallizes in the triclinic system, space group Pī witha = 9.7436(12) Å,b = 11.1836(14) Å,c = 11.5063(14) Å; α = 61.520(1)°, β = 85.019(1)°, γ = 66.864(1)° and V = 1005.6(2) Å3. Its structure is composed of Cu(II) centres with a distorted square pyramidal configuration interconnected by muco ligand in an array to generate zig-zag chain. A three- dimensional (3D) supramolecular network is formed among 1D chains of 1 via hydrogen bonding and π··π interactions. Interestingly, the connectivity of lattice water molecules shows a water dimer cluster, which further undergoes hydrogen bonding along with coordinated water molecules and oxygen atoms of muco ligands to generate an octameric cluster with chair-like hexameric unit. The excellent coordinating characteristics of muco and bipyridine ligands owing to non-covalent interactions to stabilize compound1have been investigated by means of Hirshfeld analysis. The density functional theory (DFT) study is performed to calculate the HOMO-LUMO gap which enlightens the possible future application of 1 as a semiconducting device. The theoretical findings are also validated experimentally by band gap calculation utilising Tauc’s plot exploring the UV data.