Distinctions of positional isomers of N-(methylthiazol-2-yl)nitrobenzamide by copper and iron ions

Abstract The fluorescence emissions of six positional isomers of N-(methylthiazol-2-yl)-nitrobenzamide are selectively reduced upon interactions with Cu 2+ , Fe 2+ or Fe 3+ ions among various metal ions that were studied. One isomer, namely N-(4-methylthiazol-2-yl)-3-nitrobenzamide shows reduction in the fluorescence emission intensity only upon interactions with Fe 2+ or Fe 3+ ions, enabling detection of the iron ions. Specific fluorescence emissions changes observed were used to distinguish N-(4-methylthiazol-2-yl)-3-nitrobenzamide from the other structural isomers of this compound. The positional isomers of the N-(4-methylthiazol-2-yl)-3-nitrobenzamide are difficult to distinguish at low concentrations by using other conventional techniques. On the basis of the evidences obtained from the lifetime measurements and the ESR studies, selective discrimination of Cu 2+ ions by this particular isomer is explained on the basis of the metal complex formation by the other positional isomers with Cu 2+ ions other than this isomer, such metal complexation influence the internal charge transfer processes.