Abstract：Charge-transfer complex was formed between LMX as the donor and Chloranilic Acid(CL) as the acceptor has been studied by fluorimetry. It was shown that the n-π complex can be formed at ambient temperature, which can emit，which strong fluorescence. Different variables and parameters affecting the reactions were studied and optimized. Based on this, a simple and reliable fluorescence spectroscopy method for the determination of Lomefloxacin (LMX) has been developed. Interference from some co-formulated drugs was also studied. No interference was observed due to additives commonly present in the pharmaceutical preparations. The proposed methods could be applied successfully to the investigated pure compounds and pharmaceutical dosage forms with good accuracy and precision. The linear range is 0.04-0.8 mg·L-1, the detection limit is 0.04 mg·L-1，the recoveries of LMX are 97.4%-99.3%, and RSD is 1.3%-2.6%. Finally, the charge-transfer reaction mechanism was discussed. The composition of the change-transfer complex was found to be 1∶1 by Bent-French and curved intersection methods. This ratio may be due to the presence of the fluorine atom acting as an electron drawing group in the molecule of lomefloxacin. The benzene ring has lower electron density, but nitrogen atom in 4′ of piperazingl has higher electron density and is less sterically hindered. So n-πcharge transfer complexes were formed.
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