Synthesis, Structural Characterization, and Hirschfeld Surface Analysis of a New Cu Complex and Its Role in Photocatalytic CO[sub.2] Reduction

• Published in: Molecules (Basel, Switzerland) Vol. 29; no. 9
• Main Authors: Wang, Li-Hua, Azam, Mohammad, Yan, Xi-Hai, Tai, Xi-Shi
• Format: Journal Article
• Language: English
• Published: MDPI AG 01.05.2024
• Subjects: China
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules29091957

A new Cu(II) complex, [CuL[sub.1]L[sub.2](CH[sub.3]COO)[sub.2](H[sub.2]O)]·H[sub.2]O, was synthesized by the reaction of Cu(CH[sub.3]COO)[sub.2]·H[sub.2]O, 6-phenylpyridine-2-carboxylic acid (HL[sub.1]), and 4-[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]pyridine (L[sub.2]) in ethanol-water (v:v = 1:1) solution. The Cu(II) complex was characterized using elemental analysis, IR, UV-vis, TG–DTA, and single-crystal X-ray analysis. The fluorescence properties of the copper complex were also evaluated. The structural analysis results show that the Cu(II) complex crystallizes in the triclinic system with space group P-1. The Cu(II) ion in the complex is five-coordinated with one O atom (O2) and one N atom (N1) from one 6-phenylpyridine-2-carboxylate ligand (L[sub.1]), one N atom (N2) from 4-[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]pyridine ligand (L[sub.2]), one O atom (O4) from acetate, and one O atom (O5) from a coordinated water molecule, and it adopts a distorted trigonal bipyramidal geometry. Cu(II) complex molecules form a two-dimensional layer structure through intramolecular and intermolecular O-H[sup.…]O hydrogen bonding. The two-dimensional layer structures further form a three-dimensional network structure by π-π stacking interactions of aromatic rings. The analysis of the Hirschfeld surface of the Cu(II) complex shows that the H[sup.…]H contacts made the most significant contribution (46.6%) to the Hirschfeld surface, followed by O[sup.…]H/H[sup.…]O, N[sup.…]H/H[sup.…]N and C[sup.…]H/H[sup.…]C contacts with contributions of 14.2%, 13.8%, and 10.2%, respectively. In addition, the photocatalytic CO[sub.2] reduction using Cu(II) complex as a catalyst is investigated under UV-vis light irradiation. The findings reveal that the main product is CO, with a yield of 10.34 μmol/g and a selectivity of 89.4% after three hours.