The synthesis and evaluation of o-phenylenediamine derivatives as fluorescent probes for nitric oxide detection

Abstract

A series of molecular probes for the determination of nitric oxide (NO) have been prepared. Each probe consists of an anthracene, coumarin or acridine fluorophore coupled to an electron rich o-phenylenediamine group. The o-phenylenediamine group can be substituted with methyl or methoxy groups to enhance its electron rich nature. The fluorophore fluorescence is quenched by photoelectron transfer (PET) from the aromatic amine to the lowest unoccupied orbital of the excited state fluorophore. Reaction with nitrosating species converts the o-phenylenediamine group into an electron deficient benzotriazole derivative. This group has a higher oxidation potential and does not quench the fluorophore fluorescence by photoelectron transfer so that these products are highly fluorescent. Some benzotriazole derivatives were made preparatively by alternative synthetic routes. The formation of fluorescent probes was evaluated by treatment of the precursors with nitrous fumes and S-nitroso-N-acetylpenicillamine (SNAP).