Chiral Recognition Of Ofloxacin Enantiomers Based On The Room Temperature Phosphorescence

Chapter1:Firstly, molecular recognition and its application in analytical chemistry are introduced briefly. Then, the chiral recognition and various techniques of chiral and some common chiral selectors are reviewed. Finally, the research background and main contents of the thesis are outlined simply.Chapter2:Offoxacin (OFLX) enantiomers possess strong room temperature phosphorescence (RTP) in β-cyclodextrin (β-CD) system in the presence of1,2-dibromoethane (1,2-DBE) under ambient conditions. The effects of pH, concentration of β-CD and1,2-DBE on the RTP of OFLX enantiomers have been investigated in detail. Time-resolved RTP spectroscopy shows that both OFLX enantiomers exhibit bi-exponential decay pattern with lifetimes of τ1=0.83±0.036ms and τ2=5.02±0.43ms for L-OFLX, and τ1=0.68±0.03ms and τ2=3.96±0.33ms for OFLX. The lifetime differences between the enantiomers are△τ1=0.15ms and△τ2=1.06ms, indicating that chiral discrimination of OFLX enantiomers can be achieved in β-CD/1,2-DBE system. Finally, molecular modeling was done for Ofloxacin to investigate interaction mechanism with β-CD on a molecular level; the results of molecular modeling simulation are consistent with the experimental behavior.Chapter3:OFLX enantiomers can emit strong and stable RTP emission in y-cyclodextrin system in the presence of1,2-DBE. The effects of pH, concentration of y-CD and1,2-DBE on the RTP of OFLX enantiomers have been investigated in detail.Time-resolved RTP spectroscopy shows that both OFLX enantiomers exhibit bi-exponential decay pattern with lifetimes of τ1=0.37±0.02ms and τ2=2.70±0.76ms for L-OFLX, and τ1=0.31±0.02ms and τ2=2.13±0.68ms for OFLX.The lifetime differences between these enantiomers are△τ1=0.06ms and△τ2=0.57ms. The experiment results show that the chiral recognition ability of y-cyclodextrin to OFLX enantiomers was slightly weaker than that of β-CD, and this is most likely that the difference in cavity of them as a reslut of the chiral selectivity. Chapter4:Ofloxacin enantiomers possess a strong RTP emission in sodium deoxycholate (NaDC) micellar system using Na2SO3as deoxidizer. Then the chiral recognition of OFLX enantiomers is examined based on the intrinsic chiral properties of the bile salt. The chiral discriminationa abilities of NaDC micelles in different media including in the presence or absence of inorganic salt are investigated. The experimental results show that the chiral discrimination ability of NaDC micelle exhibits a strongest to ofloxacin enantiomers in the presence of NaCl.