Theoretical analysis of the electronic properties of N3 derivatives

The structural and electronic properties of nine derivatives of the N3 complex (cis-[Ru(4,4'-COOH-2,2'-bpy)2(NCS)2]) have been studied, using density functional theory (DFT) at a hybrid (PBE0) level, with the aim of finding a systematic way to improve their spectral absorption in the visible region for photoelectrochemical applications. To this end, by means of time dependent-DFT (TD-DFT) calculations, excited states were investigated in solution to simulate UV-vis spectra. Several effects have been taken into account: the effect of the presence and deprotonation of the carboxylic groups as well as the variation of the chalcogen within the NCX ligand (X=S, Se, or Te). Besides the excellent agreement between theoretical and available experimental data, with regards to potential future experimental applications of the investigated complexes, from the calculations, the cis-Ru(dcbpyH2)(NCSe)2 may appear as a good candidate to enhance the response of the N3 dye to light, even if only slightly.