Recent studies of the photocatalytic reduction of CO2 to CO by Group VII Two strategies for improving quantum efficiencies will be emphasized.(1)Catalyst structural design to prevent non-productive mechanistic steps.The Mn(bpy)(CO)3Br catalyst precursor forms the [Mn(bpy)(CO)3]2 dimer rapidly following a photo-induced one-electron reduction by a photosensitizer [Ru(dmb)3]2+ complex. Incorporation of kinetically substitutionally inert CN- ligand in place of bromide, significantly shits the branching to the catalytically viable Mn(0) intermediate. Mn(bpy)(CO)3CN works as a catalyst with [Ru(dmb)3]2+ as photosensitizer for photocatalytic CO2 reduction in MeCN-TOEA and DMF-TEOA systems through a disproportionation mechanism. The singly reduced species Mn(bpy)(CO)3CN− is stable in DMF-TEOA Recent insights into to mechanism of photocatalysis and analysis of photophysical studies will be presented. (2) Non-covalent. intereactions between photocatalysis components to increase the efficiencies of electron transfer and catalysis. Hydrogen bonding substituents on the bipyridine ligand or the catalyst Re(dac)(CO)3Cl (dac = 4,4'-bis(methyl acetamidomethyl)-2,2'-bipyridine) have shown alteration of the mechanism for electrochemical CO2 reduction from a single site two-electron process to a two-site single-electron process, at significantly lower potential. We report studies of new photocatalyst/photosensitizer hydrogen-bond forming diads. Higher TOFs and quantum yields are observed in these H-bonding system than in the corresponding the Re(dac)+ Ru(dmb)3 systems at short irradiation times. The details of photocatalytic and photophysical studies will be reported.

Structural influences and non-covalent interactions in photocatalytic CO2 reduction by the M(bpy-R)(CO)3X (M = Mn or Re) class of complexes

2019 Spring National Meeting

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