Application of styrylquinolinium dyes as spectroscopic probes in radical polymerization process

The results of investigations concerning the organic salts compounds of D-pi-A(+)X(-) type consisting of organic alkylquinolinium cation (electron acceptor A(+)), bonded via pi electrons system with N,N-dialkylaniline group (electron donor D), and inorganic iodide anion (X-) (Table 1) were discussed. The effect of environment polarity on the spectroscopic properties of such salts used as fluorescent probes was evaluated. Absorption (Fig. 1) and fluorescence spectra (Fig. 2-4) in the solvents differing in polarity: tetrahydrofuran (THF) and dimethylformamide (DMF) were recorded. The changes in the fluorescent spectra of the compounds tested during thermally initiated methyl methacrylate polymerization (Fig. 5-7) were investigated. This way their usability for polymerization process monitoring, as fluorescent probes, has been determined. Comparatively, a relative parameter called probe sensitivity (Table 2) was introduced.