Importance of steric bulkiness of iridium photocatalysts with PNNP tetradentate ligands for CO₂ reduction

Abstract

A series of Ir complexes has been developed as multifunctional photocatalysts for CO2 reduction to give HCO2H selectively. The catalytic activities and photophysical properties vary widely across the series, and...

Influence of a neighbouring Cu centre on electro- and photocatalytic CO2 reduction by Fe-Mabiq

“…This is, to our knowledge, one of the highest TONs reported for a self-sensitized system, particularly employing earth-abundant transition metals; and in stark contrast to the behaviour of 1. 21 Thus, although the monometallic Fe-Mabiq complex is photoactive, 22 the formation of key intermediates in the CO 2 reduction pathway still require an added photosensitizer. The Mabiq coordinated Cu-Xantphos moiety in 2 may serve as the photosensitizer under the photocatalytic conditions; [Cu(Xantphos)(Biquinoline)] + complexes are known photosensitizers.…”

Kappa what? Insights into the coordination modes of N2P2 ligands

“…42 Further investigations saw that the bulkier substituents on the bipyridine and phosphine moieties stabilized the catalyst and improved its durability to give higher TON and turnover frequency (TOF). 43 The best catalyst (R = Cy with a 4,4 mesityl 2,2 bipyridine backbone) achieved a total…”

Mechanism of photocatalytic CO2 reduction to HCO2H by a robust multifunctional iridium complex

“…[14][15][16][17][18][19] Additional studies indicate that the electron transfer between PS and CAT can be facilitated by connecting the PS and CAT with a linker. [20][21][22][23][24][25] More recently, the function-integrated molecular transition metal complexes that act as both PS and CAT have been applied in the photochemical reduction of CO 2 [26][27][28][29][30][31][32][33][34] to enhance the efficiency further. However, these homogeneous photochemical CO 2 reduction systems generally focus on CO formation, whereas the selective production of HCO 2 H, a widely used energy-enriched compound in both laboratory and industry, is rarely reported.…”

“…41,42 Plus, the undesired hydrogen evolution reaction (H + / H 2 , with a redox potential of −0.41 V in water, pH = 7) seems unavoidable during the CO 2 reduction in aqueous medium, as it is thermodynamically more favorable than CO 2 reduction. Noteworthy, a highly selective photocatalytic CO 2 reduction toward HCO 2 H formation catalyzed by a function-integrated Ir III photocatalyst (named Mes-IrPCY2, in Scheme 1) was recently reported by Saito et al 34,40 The iridium complex Mes-IrPCY2 containing a bulky tetradentate PNNP ligand can function as both the PS and CAT in the reaction system. Under the irradiation with visible light and the application of BIH (1,3dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole) as the electron donor in CO 2 -saturated N,N-dimethylacetamide (DMA) and H 2 O (9 : 1 v/v) mixture, the system achieved a high catalytic selectivity of 87% toward HCO 2 H formation with a turnover number of 2080 for HCO 2 H, 470 for CO, and 15 for H 2 in 150 hours.…”