Enhancing Photocatalytic Hydrogen Generation: the Impact of the Peripheral Ligands in Ru/Pd and Ru/Pt Complexes

Abstract

The synthesis, photophysical properties and photocatalytic efficiency of a range of novel supramolecular assemblies of the type [Ru(dceb) (μ-bisbpy)MCl ][PF ] and [Ru(bpy) (μ-bisbpy)MCl ][PF ] (M=Pd or Pt, dceb=diethyl 2,2'-bipyridine-4,4'-dicarboxylate, bpy=2,2'-bipyridine and bisbpy=2,2':5',3'':6'',2'''-quaterpyridine) are reported. Photocatalytic hydrogen generation was dependent on the nature of the peripheral ligand, on the catalytic centre and on the amount of water present in the photocatalytic mixture. The best catalytic conditions were obtained with the dceb peripheral ligand (turnover numbers up to 513 after 18 h). The experimental data and DFT calculations on both the bpy- and dceb-based compounds indicated that the peripheral dceb ligands participated in the photocatalytic process.

Photo‐ and Electrochemical Properties of a CO2 Reducing Ruthenium–Rhenium Quaterpyridine‐Based Catalyst

“…In the case of the dinuclear complex ( 5 ), spectral features with λ max at 450, 323 and 287 nm are apparent. The feature with a λ max at 450 nm is assigned to a 1 MLCT and is expected to contain a contribution from both Ru→bipyridine and Ru→quaterpyridine based on the literature ,,. Our calculations, as discussed later, suggest that this transition is mainly Ru→bipyridine charge transfer in character.…”

“…The synthesis of the mononuclear Ru‐quaterpyridine complex ( 3 ) and the quaterpyridine ligand has been reported elsewhere . The rhenium complex ( 4 ) was synthesised under an Ar atmosphere, through the slow addition of Re(CO) 5 Cl to 2,2′ : 5′,3′′ : 6′′,2′′′‐quaterpyridine in toluene at reflux temperature.…”

“…The 1 H NMR and COSY spectra of all the compounds are included in the Supporting Information (Figures S1–8). The assignments for the protons in these spectra are in agreement with those of other related compounds . Further details on the assignments are available within the experimental section.…”

“…All potentials were referenced with respect to the Fe 2+/3+ couple of ferrocene. The synthesis of 3 , the precursor to 5 has been reported previously …”

Synthesis and Isotope Effects on the Excited State Properties of N^N Bound [Ir(polypyridyl)2Cl2]PF6 Complexes

“…In Table , a number of the complexes exhibit the influence of deuteration on the emission lifetime. An added advantage to selective deuteration is that the deuterated ligands are silent in 1 H NMR, thereby simplifying the characterisation of the compounds obtained . The deuterated analogues of the polypyridyl complexes obtained in this study show, apart from compounds V/VI , lifetimes at 77 K that are longer than their non‐deuterated analogues.…”