Chemiluminescence enhanced by intramicellar energy transfer

Abstract

This study deals with the Chemiluminescence (CL) of luminol and luminol-related compounds, luminol (I), isoluminol (II), cyclic hydrazide of phthalic acid (III), and their N-substituted derivatives (IV, V, VI), enhanced by intramicellar transfer of electronic excitation energy. Based on the concentration dependences of the quenching of emission of the primary emitters and the increasing emission of enhancers, we verified the theory of energy transfer in micellar complexes with an efficiency approaching 100%. The complex formation and concomitant effects (concentration-dependent self-quenching of fluorescence, inner filter effect) were optimized in order to reach the maximum conversion of CL into electronic excitation energy of the added enhancers. The cooperative effect of cationoid surfactants and fluorescent energy acceptors on the enhancement of the CL intensity was extended to less ‘efficient’ CL reactions, including biochemically and bioanalytically interesting luminol derivatives and to the reactions of catalyzed horseradish peroxidase (HRP) coupled with progesterone. It was evident that the enhancement of the CL intensity was a generally applicable procedure, independent of the choice of catalysts, and enhancers, thus enabling the combination of CL compounds with almost any acceptor. By intramicellar energy transfer, the CL of all the substances studied was strongly enhanced, including the very weak (quantum yields φ CL ≥ 0.00001) Chemiluminescence parent compounds in the series, such as cyclic phthalhydrazide.