Nitric oxide generation study of unsymmetrical β-diketiminato copper(II) nitrite complexes

Kuldeep Chand; Yu-Cheng Chu; Tzai-Wei Wang; Chai-Lin Kao; Ya-Fan Lin; Ming-Li Tsai; Sodio C N Hsu

doi:10.1039/d1dt03711k

Nitric oxide generation study of unsymmetrical β-diketiminato copper(II) nitrite complexes

Dalton Trans. 2022 Mar 1;51(9):3485-3496. doi: 10.1039/d1dt03711k.

Authors

Kuldeep Chand¹, Yu-Cheng Chu¹, Tzai-Wei Wang², Chai-Lin Kao¹, Ya-Fan Lin^{1

3}, Ming-Li Tsai^{1

2}, Sodio C N Hsu^{1

2

4}

Affiliations

¹ Department of Medicinal and Applied Chemistry, Drug Development and Value Creation Research Center, Kaohsiung Medical University, Kaohsiung 807, Taiwan. sodiohsu@kmu.edu.tw.
² Department of Chemistry, National Sun Yat-Sen University, Kaohsiung 804, Taiwan.
³ Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 807, Taiwan.
⁴ Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 807, Taiwan.

PMID: 35142315
DOI: 10.1039/d1dt03711k

Abstract

β-Diketiminato copper(II) L1CuCl-L4CuCl and their nitrite complexes L1Cu(O₂N) and L2Cu(O₂N) have been synthesized and characterized. X-ray analysis of the L1CuCl-L4CuCl complexes clearly reveals their mononuclear structure with a four-coordinated Cu(II) center bound by one chloride and three nitrogen atoms of unsymmetrical β-diketiminato ligands. Cyclic voltametric analysis of the Cu(II) complexes shows that the length of the pyridyl arm controls the Cu(II)/Cu(I) redox process. DFT and EPR results confirm that the geometry of the Cu(II) complexes is also controlled by the length of the chelating pyridyl arm. The oxygen atom transfer nitrite reduction of the Cu(II) nitrite complexes leads to the formation of copper(I)-PPh₃ and OPPh₃ which were confirmed by ¹H and ³¹P NMR. The length of the pyridyl arm of the copper(II) nitrite complexes governs the NO-releasing ability. These findings illustrate the important bioinspired behaviour and NO generation from nitrite via oxygen atom transfer of the unsymmetrical β-diketiminato copper(II) complexes as compared to symmetrical β-diketiminato copper(II) complexes.