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Updated: Aug 6, 2026
![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst
Published on: May 21, 2019
Square-pyramidal copper(ii)-Schiff base complexes with methoxy/ethoxy-phenolate and chloro-benzophenone substituents
Imdadul Haque1, Galib Abdullah1, Kashfia Azad Tuba1
1Department of Chemistry, Jahangirnagar University Dhaka-1342 Bangladesh enamullah@juniv.edu.
Abstract:
The Schiff bases, (E)-2-(((2-benzoylphenyl)imino)methyl)-6-methoxyphenol (HL1), (E)-2-(((2-benzoylphenyl)imino)methyl)-6-ethoxyphenol (HL2) and (E)-2-(((2-benzoyl-4-chlorophenyl)imino)methyl)-6-ethoxyphenol (HL3) react with copper(ii) acetate to give [Cu(L1)2] (1), [Cu(L2)2] (2) and [Cu(L3)2] (3) complexes, respectively. Structural analyses revealed that the Schiff bases adopt the conventional enol-imine O-H⋯N(imine) form stabilized by an intramolecular hydrogen bond. The structures of the complexes show coordination of two N,O-chelate ligands to the Cu(ii) atom with trans-N,N' and -O,O' configuration and a long fifth elongated coordination Cu⋯O[double bond, length as m-dash]C(benzoyl) in an overall square-pyramidal geometry (τ 5 = 0.005-0.031). Each structure contains a single crystallographically independent molecule within the asymmetric unit. The experimental and simulated PXRD profiles are in good agreement, confirming the phase purity and integrity of bulk microcrystalline samples consistent with those of the single crystals. DSC analyses suggest a simple melting of solid crystals (i.e., m.p.) with an irreversible phase change. Cyclic voltammetry (CV) measurements show two successive one-electron charge-transfer redox processes of the complexes. DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assays demonstrate that the free Schiff bases exhibit higher antioxidant activity than corresponding copper(ii) complexes. Finally, molecular modeling by DFT/TD-DFT and MO calculations reproduce the experimental results of the absorption spectra and molecular structures.
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