μ-Pyridine-bridged copper complex with robust proton-reducing ability

Abstract

The binuclear copper complex [Cu(DQPD)]2 (where DQPD = deprotonated N,N-di(quinolin-8-yl)pyridine-2,6-dicarboxamide (DQPDH2)) was synthesised and characterised by various spectroscopic as well as electrochemical techniques. The binuclear copper complex was converted into a mononuclear one by the addition of 2 equivalents of pTsOH into [Cu(DQPD)]2. The interconversion between the dimer and monomer complex was studied through UV-Vis spectroscopy and cyclic voltammetry. The mononuclear copper complex showed high catalytic activity towards electrochemical proton reduction using acetic acid as the external proton source in 95 : 5 (v/v) DMF/HO. It showed an i/i (where i is the catalytic current in the presence of acetic acid and i is the reduction peak current in absence of acid) value of 24 and a turnover rate (TOF) of 111.70 s at a scan rate of 100 mV s at 25 °C. The [Cu(DQPD)]2 complex evolved hydrogen under the irradiation of visible light in the presence of fluorescein (Fl) as a photosensitizer and triethylamine (TEA) as the sacrificial electron donor with an initial TOF of 0.03 s with respect to the catalyst.

Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes

“…333 In contrast, Cu 2 3 gave a TON H2 of 2135 over 20 h in H 2 O:DMF (1:4) with TEA and PS8 using visible LED light. 341 While Cu 2 3 was stable over 12 h under irradiation in H 2 O:DMF (1:4), reactivation of photocatalysis after 22 h required addition of HEC, rather than PS. 341…”

“…341 While Cu 2 3 was stable over 12 h under irradiation in H 2 O:DMF (1:4), reactivation of photocatalysis after 22 h required addition of HEC, rather than PS. 341…”

Electrocatalytic hydrogen production by dinuclear cobalt(ii) compounds containing redox-active diamidate ligands: a combined experimental and theoretical study

“…of TsOH to give a monocopper species that catalyzed proton reduction. 20 The dicobalt unit in 1 is more robust than its copper counterpart, indicating the structure is likely retained throughout the catalytic process. In it notable that 4 equiv.…”

“…5,8 However, recent studies have shown that ligand-assisted and ligand-centered mechanistic pathways significantly improve the kinetics and lower the overpotential of the HER by obviating the need the generate an electron rich Co ion. [15][16][17] In such mechanisms, the protonation occurs at the ligand, [18][19][20][21] and the protons subsequently interact with a metal-hydride to release H 2 . Furthermore, it has been shown that redox non-innocent ligands participate in the H 2 evolution pathways of various metal complexes, by contributing both protons and electrons.…”

“…Herein, we describe the synthesis, physicochemical and structural characterization, and electrocatalytic H 2 production of two dicobalt(II) complexes with the redox-active ligands N 2 , N 6 -di(quinolin-8-yl)pyridine-2,6-dicarboxamide (H 2 L), 20,21 and its tert-butyl analogue (H 2 L Bu ) shown in Scheme 1. The electron-releasing tert-butyl group has been incorporated into the 4-position of the pyridine moiety in the multidentate ligand in order to investigate the structure-function relationship.…”