Mechanism Based Design of Amine Fluorogenic Derivatization Reagents: Proof of Concept, Physical–Chemical Characterization and Initial Analytical Derivatization Protocols

Abstract

Herein, are described initial efforts in the design of a fluorogenic reagent applicable for the derivatization of primary and secondary amines. The initial reagent, 3-isothiocyanato-2-chloropyridine was based on physical–organic reactivity considerations to redirect the initial product of reaction between an amine and the isothiocyanate functional group, long established as a robust first step in Edman sequencing of peptides. The proposed chemistry results in the formation of a class of bicyclic fluorescent heterocycle (N,N-di-substituted [5,4-b] pyridine amines) bearing the amine analyte as substituents. Reported are the results regarding reaction kinetics in various relevant media, the ionization constants for a number of derivatives, and the associate UV and fluorescence spectral properties. These data and properties are utilized in the development of a derivatization protocol that is used in the establishment of calibration plots for several substances, with detection limits in the picomole mass range using liquid chromatography with fluorescence detection.