Synthesis and Characterization of a Novel Crystal Complex of Copper(II) With a Tridentate Schiff Base

This study presents a simple method for synthesizing a novel distorted octahedral copper(II) compound. The structural and electronic properties of the compound were determined using single-crystal X-ray diffraction (SCXRD). A three-coordinate Schiff base ligand (NNO system) was synthesized by condensation and fully characterized using Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (1H-NMR), carbon-13 nuclear magnetic resonance (13C-NMR), electrospray ionization mass spectrometry (ESI-MS), thermogravimetric/differential gravimetric analysis (TGA/DTG), and elemental analysis (CHN). The ligand is linked to the copper(II) ion via pyridine nitrogen, azomethine nitrogen, and enol oxygen, forming five-membered rings. The crystal structure reveals a unique and highly stable three-dimensional framework, characterized by continuous intrinsic porosity with a pore size of 5.44 angstroms and a unit cell density of 996 atoms. The compound exhibits exceptional thermal and dynamic stability, with non-covalent interactions playing a pivotal role in crystal arrangement. Hirshfeld surface analysis shows that π…π stacking interactions between phenolic rings are the primary contributor to structural stability, accounting for 45% of the total non-covalent forces. Furthermore, its distinctive structural properties make it an effective template for capturing and sequestering small molecules that are well suited to its pore dimensions, such as water (H2O), methane (CH4), Ethane (C2H6), Propane (C3H8), and carbon dioxide (CO2). Its insolubility in water and mild alcohols further enhances its performance, and the compound is expected to have strong potential for applications in catalysis, polymer chemistry, antioxidants, and corrosion inhibition. This promising activity is driven by the synergistic effects of its uncoordinated hydroxyl functional groups, active heteroatoms, and robust geometric arrangement.