Process for the Synthesis of Precursor Complexes of Titanium Dioxide Sensitization Dyes Based on Ruthenium Polypyridine Complexes

Synthesis in aqueous media of both precursor complexes and dye sensitizers for titanium dioxide based on ruthenium polypyridine complexes of general formula RuLL′X2, RuLX3 or Ru LL′L″ where L, L′, L″ is a bidentate or tridentate organic ligand which can be chosen among H2dcbpy 4,4′-dicarboxy-2-2′-bipyridyl, 5,5′-dicarboxy-2,2′-bipyridyl, 4,4′,4″-tricarboxy-2,2′,6′,2″-terpyridyl, 4,4′-dinonyl-2,2′-bipyridyl, 4,4′-bis-3,4-dioctyloxystyryl-2,2′-bipyridyl, 6-phenyl-2,2′-bipyridyl, 6-(2,4-difluorophenyl)-2,2′-bipyridyl;

• the ruthenium precursor complexes can be RuCl3.3(H2O) [RuCl6]2−, [Ru(DMSO)6(Y)2] wherein Y is selected from PF6, ClO4, Cl, Br;
• X is an anionic ligand selected from NCS−, Cl−, CN−. The microwave irradiation, whose frequency is comprised from 300 MHz to 300 GHz, is applied in a high pressure vessel (HP500) contained in a multimodal or unimodal MW reactor, at pressure values of 690 kPa to 5500 kPa.