Spectroscopic properties of fluoroquinolone antibiotics in water-methanol and water-acetonitrile mixed solvents.
The fluorescence properties of ofloxacin (OFL), norfloxacin (NOR) and flumequine (FLU) were studied in H2O-CH3OH and H2O-CH3CN mixed solvents because these solvents were thought to behave as a biological mimetic system. The emission spectra of OFL and NOR were very sensitive to the composition of the solvents. In the Lippert-Mataga analysis of the steady-state fluorescence data of OFL and NOR, clear reverse solvatochromism was exhibited in both mixed solvents. This observation can be explained by the twisted excited-state intramolecular charge transfer, which is accelerated by water. Theoretical treatments further support these results. The radiative and nonradiative rate constants were analyzed as a function of solvent dipolarity-polarizability (pi*) and hydrogen-bond donor acidity (alpha). These results were well consistent with the suggested mechanism of the excited-state chemical process of OFL and NOR, which depended upon the solvent-solute interactions such as bulk dielectric effects and specific hydrogen-bonding interactions. However, the influence of dielectric effects was more significant. The solvent structures of H2O-CH3CN and the preferential solvation by water were also examined. The emission spectra of FLU do not exhibit any characteristic responses to the properties of the environment.
Park
Hyoung-Ryun
HR
Department of Chemistry, Chonnam National University, Kwangju, Republic of Korea.
Oh
Chu-Ha
CH
Lee
Hyeong-Chul
HC
Lee
Jin-Ki
JK
Yang
Kiyull
K
Bark
Ki-Min
KM
D000097:Acetonitriles / Q000737:chemistry; D000890:Anti-Infective Agents / Q000737:chemistry*; D024841:Fluoroquinolones; D006860:Hydrogen Bonding; D000432:Methanol / Q000737:chemistry; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D014867:Water / Q000737:chemistry
D000097:Acetonitriles; D000890:Anti-Infective Agents; D024841:Fluoroquinolones; D012997:Solvents; D014867:Water; D000432:Methanol; C032159:acetonitrile