Molecular properties of two related families of substituted [Ru(2,2′: 6′,2″-Terpyridine)₂]²⁺ for application as sensitizers in dye-sensitized solar cells

A theoretical study of two families of related compounds of 4′-R substituted 2,2′:6′,2″-terpyridines (TP) with Ruthenium as central metal is presented (one family is homoleptic and the other family is heteroleptic). The influence of the 4′-R substituent over the electronic structure, reactivity indexes and the electronic transitions in the UV-Vis spectra is studied. A proposal of a group of dyes not synthesized yet that could be efficient dyes to sensitize a semiconductor like TiO₂ in an energy conversion device like a DSSC is made. Due to the presence of the carboxylic anchor group, the results of the direction of the calculated excitations and the charge transfer of the TP ligand, suggest that the most effective dyes are the heteroleptic TP with an electron-donor substituent over one terpyridine ligand and one carboxylic acid group in the 4′ position of the second TP ligand.