Syntheses and photophysical properties of some 4-arylpyridinium salts

A number of 4-arylpyridines, many methoxy substituted, were prepared by an efficient two-step method involving aryl Grignard addition to 1-methyl-4-pi peridone and direct aromatization of the resulting 4-aryl-4-piperidinols. T he pyridines were N-alkylated to give sulfonate salts desired for their flu orescent properties. Study of selected compounds as laser dyes revealed sev eral structures to be efficient dyes lasing in the 530-550 nm range. Two ne w diazaquaterphenyls were prepared and were quaternized. These salts exhibi ted intense fluorescence in the 420-450 nn range, but would not lase. A phe nolic azaterphenyl suitably substituted for excited state intramolecular pr oton transfer (ESIPT) did not fluoresce at all.