Dr Mary Pryce

The bridging ligand 2,2′,5′,3′′,6′′,2′′′‐quaterpyridine was utilised to tether [(bpy)₂Ru]²⁺ and [Re(CO)₃Cl] subunits for the purpose of photocatalytic CO₂reduction. The photophysics and electrochemistry of the complex and associated mononuclear species are reported herein, in addition to photocatalytic, picosecond time‐resolved infrared and computational studies. Photophysical, time‐resolved IR, and electrochemical data together with quantum chemical calculations indicate weak communication between the two metal centres. As a result of the electron‐withdrawing effect of the ligand on both the Ru and Re subunits, the reducing power of the photosensitiser and catalytic unit were significantly attenuated relative to the intermolecular approach utilising [(bpy)₃Ru]²⁺ and (bpy)Re(CO)₃Cl.

The bridging ligand 2,2′,5′,3”,6”,2”’-quaterpyridine was utilized to tether [(bpy)2Ru]2+ and [Re(CO)3Cl] subunits for the purpose of photocatalytic CO2 reduction. The photophysics and electrochemistry of the complex and associated mononuclear species are reported herein, in addition to photocatalytic, picosecond time-resolved infrared and computational studies. Photophysical, time resolved IR, and electrochemical data together with quantum chemical calculations indicate weak communication between the two metal centres. Due to the electron withdrawing effect of the ligand on both the Ru and Re subunits, the reducing power of the photosensitizer and catalytic unit were significantly attenuated relative to the intermolecular approach utilizing [(bpy)3Ru]2+ and (bpy)Re(CO)3Cl, whereby neither an oxidative or reductive quenching electron transfer pathway was suggested as feasible.

A series of supramolecular assemblies of the type [Ru(L-L)2(L’-L)MX2)]n+ are reported where L-L is 2,2′-bipyridine (bipy), 4,4′-di-tetra-butyl-bipyridine (tbbipy) or 4,4′- diethoxycarbonyl-2,2′-bipyridine (dceb), L-L’ is tetrapyrido[3,2-a:2′,3′-c:3”,2”-h:2”’,3”’- j]phenazine (tpphz), 2,2′:5′,2”-terpyridine (2,5-bpp), 2,2′:6′,2”-terpyridine, (2,6-bpp), 2,5- di(pyridine-2-yl)pyrazine (2,5-dpp) or 2,3-di(pyridine-2-yl)pyrazine (2,3-dpp), and MX2 is PdCl2, PtCl2 or PtI2. The photocatalytic behaviour with respect to hydrogen generation of these compounds and their ultrafast photophysical properties are discussed as a function of the nature of the peripheral ligands, the bridging ligands and the catalytic centre. The results obtained show how differences in the chemical composition of the photocatalysts can affect intramolecular photoinduced electron transfer processes and the overall photocatalytic efficiency.