Chemical Fixation of Atmospheric CO₂ by Copper(II) Complexes of a Tridentate N‐donor Ligand

Abstract

Using an unsymmetrical tridentate N‐donor ligand (2‐pyridylethyl){2‐(1‐methylimidazolyl)methyl}methylamine (L3), synthesis, spectral (IR, UV/Vis, ESI‐MS, and EPR), magnetic (as solid/in solution) and redox properties of a monomeric green [(L3)CuIICl2]·MeOH (1), a dimeric light‐blue [{(L3)CuII(μ‐OH)}2](ClO4)2 (2), a dimeric blue [{(L3)CuII(μ‐OMe)}2](ClO4)2 (3), and a trimeric ink‐blue [{(L3)CuII(OClO3)}3(μ3‐OCO2)](ClO4) (4) complexes were achieved. Complexes 1, 3, and 4 were structurally characterized. Isolation of 4 was achieved by the reaction between {(L3)2CuII2(μ‐OH)2}2+ species (formed from the reaction between (i) solution‐generated yellow [(L3)CuI(MeCN)]1+ species and O2, followed by reaction with moisture and (ii) 1 and NaOH in water and CO2 in open air, under ambient conditions. Reactivity of 2 with MeOH results in the formation of 3. The observed CO2 fixation by reactive complex 2 to afford 4 was rationalized, through designed experiments including kinetic measurements. Thermodynamic parameters of HCO3–/CO2 binding were also derived. Temperature‐dependent magnetic measurements of 4 indicated a ferromagnetic exchange‐coupling (J = 48 cm–1). Notably, 4 exhibits largest ferromagnetic coupling (J = 48 cm–1) amongst all complexes reported so far with similar mode of carbonate‐bridging.

Structural Variety of Isopropyl-bis(2-picolyl)amine Complexes with Zinc(II) and Copper(II)

“…The ESR study also confirms that the coupling in the triangle must be ferromagnetic, in line with the magnetization study of similar trinuclear copper complexes. 55,72,73 Here, instead of using three copper spins with S = 1/2 that interact through three equivalent superexchange patways, 55,73 and Hamiltonian (4) the simulations were simplified using effective total spin of the triangle S = 3/2 with small magnetic anisotropy described by zero-field splitting term D = 1.18 GHz = 0.04 cm −1 . In this rough approximation, the agreement between experimental and simulated spectra for complex 3b Cu is satisfactory.…”

A Zinc Coordination Complex Mimicking Carbonic Anhydrase for CO2 Hydrolysis and Sequestration

“…Effectively eliminating CO 2 is of great significance for CA’s catalytic performance and application . Thus, the conversion of CO 2 into CaCO 3 was conducted to evaluate the biomimetic applicability of compound 1 .…”

“…Effectively eliminating CO 2 is of great significance for CA's catalytic performance and application. 35 Thus, the conversion of CO 2 into CaCO 3 was conducted to evaluate the biomimetic applicability of compound 1. The weight of formed CaCO 3 converted from CO 2 can be used to assess the CO 2 hydration and sequestration efficiency.…”