The Importance of CH···X (X = O, π) Interaction of a New Mixed Ligand Cu(II) Coordination Polymer: Structure, Hirshfeld Surface and Theoretical Studies

Saikat Seth

doi:10.3390/cryst8120455

Abstract

In this study, a new equimolar (1:1:1) mixed ligand Cu(II) polymer, [Cu(IDA)(ImP)]n (1) with iminodiacetato (IDA) and imidazo[1,2-a]-pyridine (ImP) was synthesized and characterized by single crystal X-ray diffraction analysis. X-ray crystallography reveals that compound (1) consists of polymeric zigzag chain along [010] the carboxylate carbonyl oxygen atom by two-fold symmetry screw axis. The solid-state structure is stabilized through C–H···O hydrogen bonds and C–H···π interactions that lead the molecules to generate two-dimensional supramolecular assemblies. The intricate combinations of hydrogen bonds and C–H···π interactions are fully described along with computational studies. A thorough analysis of Hirshfeld surface and fingerprint plots elegantly quantify the interactions involved within the structure. The binding energies associated with the noncovalent interactions observed in the crystal structure and the interplay between them were calculated using theoretical DFT calculations. Weak noncovalent interactions were analyzed and characterized using Bader’s theory of ‘‘atoms-in-molecules’’ (AIM). Finally, the solid-state supramolecular assembly was characterized by the “Noncovalent Interaction” (NCI) plot index.

Highlights

Coordination polymers (CPs) and/or metal-organic framework (MOFs) [1,2,3] represent multi-dimensional periodic structures of metal ions that are interconnected by organic bridging ligands, and have attracted great interest from scientists in the fields of crystal engineering, materials science, and supramolecular chemistry [4,5]
In the construction of CPs, carboxylates and N-donor ligands have been widely chosen [13,14,15] as building blocks mainly due to two aspects: (i) They can exhibit rich coordination modes and (ii) they can participate in hydrogen bonding interactions by acting as donors and/or acceptors
Crystal structure analysis reveals that compound (1) is a one-dimensional metal-organic coordination polymer constructed from Cu(II) ion, iminodiacetic acid, and imidazo[1,2-a]-pyridine

Summary

Introduction

Coordination polymers (CPs) and/or metal-organic framework (MOFs) [1,2,3] represent multi-dimensional periodic structures of metal ions that are interconnected by organic bridging ligands, and have attracted great interest from scientists in the fields of crystal engineering, materials science, and supramolecular chemistry [4,5]. In the construction of CPs, carboxylates and N-donor ligands have been widely chosen [13,14,15] as building blocks mainly due to two aspects: (i) They can exhibit rich coordination modes and (ii) they can participate in hydrogen bonding interactions by acting as donors and/or acceptors. The rational design of CPs is the control of linkage between the metal ions that allows the construction of particular structural motifs and the chemical properties of the crystalline solids [16,17]. Though there are suitable ligands and metal ions to obtain CPs, it is still a prodigious task to predict the final structure, depending on reaction conditions in the self-assembly [18,19]. CPs can organize their final solid-state structure by employing a variety of non-bonded interactions such as electrostatic

Methods

Results

Conclusion