Application Of 3-aminophthalic Acid And Its Derivatives In Chemiluminescence

Chemiluminescence is the process by which molecules or ions are excited to emit light by chemical reactions.In the past few decades,chemiluminescence research has been continuously developed,including the development of new luminescent molecules,the combination with nanomaterials,chemiluminescence sensors,new applications,etc.Chemiluminescence is still a promising method for ultra-high sensitivity analysis.Luminol is the most commonly used luminescent molecule in many chemiluminescence systems.However,there are still some problems to be solved about luminescence process of luminol,such as the role of the acyl hydrazine group and the high luminescence background signal associated with luminol.In this study,the luminescence of 3-aminophthalic acid,the oxidation product of luminol,was explored to investigate the luminescence behavior of 3-aminophthalic acid and H₂O₂-Co²⁺.On this basis,the luminescence behavior of3-amino-N-hydroxy-phthalic acid and 3-amino-phthalimide,two molecules with similar structure to 3-aminophthalic acid,was studied.The mechanism of these luminescence was speculated and the analytical application of these luminescent molecules were preliminary explored.The results show that the 3-amino phthalic acid,3-amino-N-hydroxy-phthalic acid,3-amino-phthalimide racted with H₂O₂-Co²⁺produced chemiluminescence in alkaline medium.Among these three molecules,3-aminophthalic acid has the strongest luminescence,followed by 3-amino-N-hydroxy-phthalic acid,and3-aminophthalimide is the weakest.The emission spectrum characteristics of the three molecules are very similar to those of Luminol.3-Aminophthalic acid-H₂O₂-Co²⁺also has similar reaction kinetics as that of Luminol.The reaction mechanism of 3-aminophthalic acid-H₂O₂-Co²⁺was studied in detail.It is speculated that 3-aminophthalic acid anion emits light by receiving the energy of the monomorphic oxygen produced in the reaction.3-amino-n-hydroxy-phthalic acid,3-amino-phthalimide with H₂O₂-Co²⁺also have similar reaction mechanisms.Preliminary application studies have shown that the chemiluminescence of3-amino-n-hydroxy-phthalic acid and 3-amino-n-hydroxy-phthalic acid was high sensitive to Co²⁺.Even without adding other sensitizing substances,the detection limit reaches about 1.1×10^-10 mol/L.In summary,even when the hydrazine group is removed from the luminol molecule,there is still a strong chemiluminescence,and the background signal is greatly reduced.This is helpful for the development of more efficient luminol derivatives and the explanation of their luminescence mechanism.However,there are only a limited number of 3 molecules were investigated.More molecules and luminescent systems still need to be studied.