l-Isoleucine-Schiff Base Copper(II) Coordination Polymers: Crystal Structure, Spectroscopic, Hirshfeld Surface, and DFT Analyses

A new copper(II) coordination polymer was synthesizedfrom the l-isoleucine-Schiff base and characterized by elementalanalysis,Fourier transform infrared (FT-IR) spectroscopy, ultraviolet-visible(UV-vis) spectroscopy, single-crystal X-ray diffraction (XRD)analysis, electronic paramagnetic resonance, and thermogravimetricanalysis. XRD analysis confirmed the square planar coordination geometryof metallic centers and a zipper-like polymer structure. Vibrational,electronic, and paramagnetic spectroscopies and thermal analysis wereconsistent with the crystal structure. A Hirshfeld surface (HS) anddensity functional theory (DFT) analyses were employed to gain additionalinsight into interactions responsible for complex packing. The quantitativeexamination of two-dimensional (2D) fingerprint plots revealed, amongother van der Waals forces, the dominating participation of H & BULL;& BULL;& BULL;Hand H & BULL;& BULL;& BULL;Cl interactions in the molecular packing. Theuse of computational methods provided great help in detailing thesupramolecular interactions occurring in the crystal, which were mainlyvan der Waals attractions. The electronic transition analysis helpedcorroborate the electronic transitions observed experimentally inthe absorption spectrum. The frequency and vibrational mode analysisgave a deeper insight into the characterization of the CuLCL complex.

Automated summary

A new copper(II) coordination polymer was synthesized and characterized. Various spectroscopic and analytical techniques were used to confirm the structure and properties of the polymer. Computational methods were employed to gain additional insight into the supramolecular interactions in the crystal. The results provided a deeper understanding of the complex packing and electronic transitions in the polymer.