Application of Fluorescent Triazoles to Analytical Chemistry. III. : Fluorescence Characteristics of 2-Phenylbenzotriazolyl-5-amine Derivatives as Fluorescent Probes

Abstract

2-Phenylbenzotriazole derivatives with a COCH₃ or NH₂ group on the 2-phenyl ring were synthesized and found to be applicable as fluorescent hydrophobic probes. The fluorescence intensities of these compounds, which were intense in non-polar solvents, were dramatically quenched in polar solvents. In particular, 2-(4-acetylphenyl)-2H-benzotriazolyl-5-amine (7) showed a much higher ratio of the fluorescence intensity in the organic solvent to that in water (F_o/F_w) than 8-anilino-1-naphthalenesulfonate (ANS) : The F_o/F_w values of 7 were 470 for dioxane and 440 for acetone, while those of ANS were 100 for dioxane and 90 for acetone.We modified compound 7 to obtain water-soluble probes for use in drug-protein binding studies and examined the interaction of these probes with human serum albumin (HSA). All the compounds, which were practically non-fluorescent in the buffer solution, bound to HSA and fluoresced.