Synthesis, characterization and Hirshfeld surface analysis of a mixed-ligand copper (II) coordination polymer from 1,4,8,11-tetraazacyclotetradecane and pyromellitic dianhydride

Abstract

One pot synthesis of a new mixed-ligand coordination polymer has been carried out by combining copper salt, macrocyclic ligand 1,4,8,11-tetraazacyclotetradecane (cyclam) and benzene-1,2,4,5-tetracarboxylic dianhydride (pyromellitic dianhydride, PMDA). The molecular composition of the synthesized complex was found to be [Cu(H2btca)2(H2O)2Cu(cyclam)]·H2O [H2btca\u2009=\u20091,2,4,5-benzene tetracarboxylic dianion]. The complex has been characterized by physicochemical and spectroscopic methods. Its crystallographic analysis shows two different types of Cu(II) atoms (Cu1 and Cu2) in octahedral environments. In the structure, the coordination of bidentate H2btca2− dianion with Cu1 atoms in 1,4-COO− position forms a two-dimensional (2D) sheet, while the O(µ2)-axial atoms of water ligands coordinated to [Cu(cyclam)]2+ units with long Cu2-Ow bond indicates a Jahn–Teller distortion effect producing a three-dimensional (3D) network. Using the same combination of ligands (cyclam and PMDA) with nickel salt led to an already reported one dimensional (1D) polymer, viz. {[Ni(cyclam)H2btca]·2H2O}n. Hirshfeld surface analysis on H2btca2− dianion along with 2D fingerprint plots was carried out in order to have an in-depth understanding of the intermolecular interactions in the crystal system.