Organic donor-pi-acceptor salts: A new type of probe for monitoring photopolymerization processes

Organic salts consisting of an organic cation, composed of an alkylated pyridinium ion linked to a dimethylamino group by a jr-system, and an inorganic anion were incorporated in polymeric networks formed by photopolymerization of dimethacrylates of different size and polarity. The response of the probe's emission to changes in its environment during photopolymerization was determined and compared with the response of 4-(dimethylamino)-4'-nitrostilbene, a typical charge transfer probe. Emissions in solvents of low viscosity but with different polarities are also reported. A mechanism to explain the probe's response is presented.