Effect of nucleotides on the charge-transfer fluorescence of trans-4-(p-N,N-dimethylaminostyryl)-N-vinylbenzylpyridinium chloride

Addition of the cyclic nucleotides cAMP and cGMP to aqueous solutions of trans-4-(p-N,N-dimethylaminostyryl)-N-vinylbenzylpyridinium chloride (1) dramatically enhanced the fluorescence quantum yield of 1 with concomitant slight red shifts of the λmax, and had slight hyperchromic and bathochromic effects on the absorbance of 1. In contrast, d-ribose-5-phosphate had no such effects. These results suggest that 1 preferentially associates with nucleotides in aqueous solution, with equilibrium constants for cAMP and cGMP of 212 ± 46 and 285 ± 18 M−1, respectively. Thus, dye 1 may serve as a starting point for the development of more sensitive and specific probes for cyclic nucleotides.