Biomimetic catalysis of nitrite reductase enzyme using copper complexes in chemical and electrochemical reduction of nitrite

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Ferreira, Millena P. P. ; Castro, Caio B. B. ; Honorato, Joao ; He, Sheng ; Guimaraes, Walber Goncalves ; Esmieu, Charlene ; Castellano, Eduardo E. E. ; de Moura, Andre F. ; Truzzi, Daniela R. ; Nascimento, Otaciro R. ; Simonneau, Antoine ; Netto, Caterina G. C. Marques

• Document type: Journal article
• Source: DALTON TRANSACTIONS; v. 52, n. 32, p. 11-pg., 2023-07-25.

Abstract

Copper nitrite reductase mimetics were synthesized using three new tridentate ligands sharing the same N,N,N motif of coordination. The ligands were based on l-proline modifications, attaching a pyridine and a triazole to the pyrrolidine ring, and differ by a pendant group (R = phenyl, n-butyl and n-propan-1-ol). All complexes coordinate nitrite, as evidenced by cyclic voltammetry, UV-Vis, FTIR and electron paramagnetic resonance (EPR) spectroscopies. The coordination mode of nitrite was assigned by FTIR and EPR as & kappa;O-2 chelate mode. Upon acidification, EPR experiments indicated a shift from chelate to monodentate & kappa;O mode, and N-15 NMR experiments of a Zn2+ analogue, suggested that the related Cu(ii) nitrous acid complex may be reasonably stable in solution, but in equilibrium with free HONO under non catalytic conditions. Reduction of nitrite to NO was performed both chemically and electrocatalytically, observing the highest catalytic activities for the complex with n-propan-1-ol as pendant group. These results support the hypothesis that a hydrogen bond moiety in the secondary coordination sphere may aid the protonation step. (AU)

• FAPESP's process: 21/04876-4 - Studies on structure & activity of RuII / arene / mercaptoligants complexes against cancer
• Grantee: João Honorato de Araujo Neto
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/17483-0 - Dinitrosyl iron complexes (DNICs): formation, reactivity, and implications for the physiopathology of nitric oxide
• Grantee: Daniela Ramos Truzzi
• Support Opportunities: Research Grants - Young Investigators Grants
• FAPESP's process: 13/07937-8 - Redoxome - Redox Processes in Biomedicine
• Grantee: Ohara Augusto
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC