Synthesis, characterization and photoelectrochemical performance of a tris-heteroleptic ruthenium(II) complex having 4,7-dimethyl-1,10-phenanthroline

The novel cis-[Ru(Me2-phen)(dcbH2)(NCS)2] complex was prepared using a one-pot route and characterized based on 1H NMR, FTIR, absorption and emission spectra. The properties of this complex were compared with those of cis-[Ru(R2-phen)(dcbH2)(NCS)2], where R = Ph or H, to establish a relationship between the donor/acceptor character of the R substituent and the observed behavior of these compounds. Computational methods were also employed to gain a comprehensive understanding of this relationship. By using electron-donating/accepting substituents, it was possible to tune both the ground and excited states of the cis-[Ru(R2-phen)(dcbH2)(NCS)2] complexes. This compound is capable of sensitizing the TiO2 surface and efficiently converting the sunlight into electricity. In comparison to cis-[Ru(Ph2-phen)(dcbH2)(NCS)2] it is observed that the presence of phenyl groups provide higher efficiency. The conversion efficiency was improved in comparison to cis-[Ru(phen)(dcbH2)(NCS)2]. This increase in efficiency is attributed to an increase in electron density, thus favoring electron transfer to TiO2.