A time resolved and steady-state fluorescence quenching study on naproxen and its cyclodextrin complexes in water

Steady-state and time-domain fluorescence quenching studies of naproxen in watts were carried out in solutions in the absence or presence of a cyclode xtrin (addition of beta -cyclodextrin or methyl-beta -cyclodextrin was inve stigated). KI and acrylamide were used as quenchers. From the steady state quenching experiments the quenching constants in the Stern-Volmer equation were found and compared for the free and the complexed molecules. The decay curves were analyzed by utilizing either a discrete one to four exponentia l fit or the lifetime distributions (exponential series method). The lifeti mes of complexes, their bimolecular quenching constants and quenching effic iencies were determined and compared with the corresponding values for free naproxen. All measurements were carried out separately for the naproxen an ion at higher pH and for naproxen acid at lower pH. (C) 2001 Elsevier Scien ce B.V. All rights reserved.