Ruthenium(ii) complex-sensitized solid-state polymerization of diacetylene in the visible light region

10,12-Pentacosadiynoic acid (DA) hybrid films with various loadings of a ruthenium(II) complex ([Ru(dpphen)3]Cl2) (0.5 to 4.6 mol%) were prepared by spin-coating. Solid-state polymerization of diacetylene monomers can be sensitized in the visible light region by embedding [Ru(dpphen)3]Cl2 into the hybrid films. In situ absorption measurement enables us to study the polymerization kinetics of DA monomers in the hybrid films. The polymerization process can be described by a first order rate equation and the polymerization rate constants are determined and discussed in detail. The mechanism of the sensitization is discussed, and an explanation based on photo-induced electron transfer from[Ru(dpphen)3]Cl2 to DA moiety is presented. Strong quenching of [Ru(dpphen)3]Cl2 fluorescence was observed even at a low monomer conversion. Enhancement of polydiacetylene (PDA) fluorescence could be observed in the presence of [Ru(dpphen)3]Cl2. The mechanism of energy migration from the [Ru(dpphen)3]Cl2 molecules to the polymer chains is also presented.