Interaction of 3-aminophthalhydrazide with 5-hydroxytetracycline and chloramphenicol: a fluorescence quenching study

The fluorescence quenching of 3-aminophthalhydrazide (luminol) due to the interaction with 5-hydroxytetracycline (teramycin, HTC) and chloramphenicol (chloromycetin, CLM) has been studied employing steady-state and time-correlated single photon counting techniques. In the case of luminol-HTC system, complex formation in the ground stale is assumed to explain the higher Value of the quenching rate constant and is consistent with positive curvatures in the Stern-Volmer (S-V) plots. The equilibrium constant for the complex formation by hydrogen bonding interaction has been calculated from absorption spectral changes. On the other hand, linear S-V plots are obtained in the case of luminol-CLM system and the bimolecular rate constants obtained in this case are found to be similar to the rate constant for diffusion controlled process. A plausible explanation of the quenching mechanism has been discussed on the basis of hydrogen bending interaction between the colliding species. (C) 1998 Elsevier Science B.V. All rights reserved.