Synthesis and Characterization of a Series of Bis-homoleptic Cycloruthenates with Terdentate Ligands as a Family of Panchromatic Dyes

Abstract

A series of six homoleptic bis-cyclometalated ruthenium complexes, Ru(N^N^C), is reported where N^N^C is a 6-(2,4-difluoro-3-R-phenyl)-4-R-4'-R-2,2'-bipyridine with R = -H or -CF and R and R = -COOEt or -CF. An effective synthesis of the ligands and the complexes is described. The UV-visible absorption studies demonstrate that these complexes are panchromatic dyes absorbing up to 900 nm. Importantly, the onset of absorption depends only on the substitution on the metalated phenyl, whereas the intensity of absorption throughout the spectra is a function of substituents on both the phenyl and the bipyridine moieties. The same trend is observed in electrochemistry as the redox gap depends only on the substitution on the metalated phenyl, whereas the oxidation and reduction potentials are a function of substituents on both the phenyl and the bipyridine moieties. Preliminary tests as sensitizer for dye-sensitized solar cells demonstrate that the number of anchoring groups on the dye has a major influence on the device efficiency.

Capturing the interplay between spin–orbit coupling and non-Condon effects on the photoabsorption spectra of Ru and Os dyes

“…This observation suggests that non-Condon effects can compete with the influence of spin-orbit coupling transitions in the overall shape of the low-energy tail of the 1-Ru absorption spectrum. Hence, these results highlight the potential influence of nuclear configurations on the interpretation of electronic spectra of Ru complexes, but appear to confirm the assignment of the low-energy tail of the absorption spectrum as exhibiting dominantly a 1 MLCT character 33 . It is also interesting to note that nuclear geometry sampling does not alleviate the apparent tendency of LR-TDDFT/PBE0 to overestimate the excitation energies: the calculated spectra remain blue-shifted with respect to the experimental spectrum.…”

“…1-Ru exhibits an absorption spectrum with a low energy tail at around 700 nm (see upper panel of Fig. 3), and previous calculations based on a SP strategy and LR-TDDFT (without the inclusion of SOC) suggested that this low-energy tail should be dominated by singlet metal-to-ligand charge transfer ( 1 MLCT) transitions 33 . We propose here a study of 1-Ru combining the Nuclear Ensemble Approach with relativistic LR-TDDFT, allowing us to decipher the role played by SOC and non-Condon effects in the low-lying transitions of 1-Ru.…”

Influence of Mesoionic Carbenes on Electro- and Photoactive Ru and Os Complexes: A Combined (Spectro-)Electrochemical, Photochemical, and Computational Study

“…All compounds were submitted to cyclic voltammetry to elucidate the electrochemical behavior of the complexes, which can often provide indirect indications of the HOMO/LUMO gap of such systems. Ruthenium and osmium polypyridyl complexes usually display rich redox chemistry, and the influence of the substitution pattern on the pyridine rings is well-defined and was intensively studied in the last few decades. − Table summarizes the results of the measurements in anhydrous acetonitrile. The potentials for the homoleptic bipyridine complexes are listed for purposes of comparison.…”