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Spectroscopic Properties of Fluoroquinolone Antibiotics and Nanosecond Solvation Dynamics in Aerosol‐OT Reverse Micelles
Author(s) -
Park HyoungRyun,
Lee HyeongChul,
Kim Tae Heung,
JinKi Lee,
Yang Kiyull,
Bark KiMin
Publication year - 2000
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1562/0031-8655(2000)0710281spofaa2.0.co2
Subject(s) - micelle , chemistry , solvation , nanosecond , emission spectrum , intramolecular force , stokes shift , photochemistry , pulmonary surfactant , relaxation (psychology) , analytical chemistry (journal) , chemical physics , spectral line , fluorescence , solvent , organic chemistry , aqueous solution , laser , physics , optics , psychology , social psychology , biochemistry , quantum mechanics , astronomy
Among fluoroquinolone antibiotics, ofloxacin (OFL) and norfloxacin (NOR) have piperazinyl groups but flumequine (FLU) does not have this substitutent. The emission spectra of OFL and NOR are strong, broad structureless bands with large Stokes' shifts in water but the emission intensities are very weak in organic solvents. Thus we find that these compounds exist as different chemical species in various solvents. A continuous red shift in the emission bands for OFL and NOR is observed as the water concentration within the aerosol‐OT (AOT; sodium 1,4‐bis[2‐ethylhexyl]sulfosuccinate) micelle increases or temperature of this solution rises. From the fluorescence anisotropy measurements of OFL and NOR, we assume the intramolecular charge transfer after excitation from the nitrogen of the piperazinyl group to the keto oxygen. Theoretical calculations further support this observation. Multifrequency phase and modulation experiments and time‐resolved emission spectra clearly show the occurrence of intramolecular charge transfer and the subsequent nanosecond water reorganization around OFL or NOR in the AOT micelle. Upon increasing the water concentration within the AOT micelle, the relaxation rate increases because of the large amount of free water. The emission spectra of FLU do not exhibit any significant response to the physical properties of their environment.