EFFECT OF PH ON PHOTOPOLYMERIZATION REACTION OF ANILINE DERIVATIVES WITH THE TRIS(2,2'-BIPYRIDYL)RUTHENIUM COMPLEX AND THE METHYLVIOLOGEN SYSTEM

Photopolymerization of aniline derivatives was revealed to be induced by photoinduced electron transfer (PIET) between the tris(2,2'-bipyrid yl)ruthenium complex [Ru(bpy)(3)(2+)] and electroactive molecules. Sin ce the initial photopolymerization reaction depended on PIET between R u(bpy)32+ and N-phenyl-p-phenylenediamine (PPD), the effect of pll of the polymerization solution on the PIET was investigated to improve th e efficiency of the photopolymerization reaction. At lower pH, the que nching reaction of [Ru(bpy)(3)(2+)] by PPD proceeded with low efficie ncy due to electrostatic repulsion between molecules concerning the PI ET. This was clarified, by comparison with the results concerning the photochemistry in a higher pH solution. On the other hand, a lower pH should be required to induce the propagation because a lower pH inhibi ted the deprotonation of both aniline derivative and growing poly(anil ine) chain. From the detailed analyses for both initial and propagatio n reactions, the increase in ionic strength was revealed to be a solut ion to improve the photopolymerization efficiency even in low pH.