Solvatochromic Effects And Photophysical Properties Of Levofloxacin And Norfloxacin Drugs And Their Fluorescence Quenching Mechanism With Caffeine Using Spectroscopic And Computational Methods

Abstract

Levofloxacin (Lvf) And Norfloxacin (Nrf) Are Among Groups Of Fluoroquinolone Antibiotics, Broad-Spectrum Used To Treat Various Infections Caused By Many Bacterial Species. The Drugs Contain Functional Groups Which Control The Type And Degree Of Interaction With Different Solvents. In This Research, The Effects Of Solvent Polarity On Lvf And Nrf Drugs Were Determined Using Spectroscopic And Computational Work To Realise Change In Electronic Properties And Geometrical Structure Of The Drugs. The Results Indicated That, The Emission Spectra Are More Strongly Affected By Solvent Polarity Than The Absorption Spectra. The Calculated Excited State Dipole Moment Is Larger Than That Of The Ground State Dipole Momentwhich Indicate The Probe Compounds Are Significantly More Polarized In The Excited State Thanin The Ground State. From Computational Work, The Homo-Lumo Energy Bandgap, The Dipole Moments, Electron Charge Density Distribution, And Oscillator Strength Were Determined Using The Semi-Empirical Mp6 Method, Dft-B3lyp-3-21g, And Dft-B3lyp-6-31g Employing Gaussian 09 Software. Large Dipole Moments Were Obtained By Computational Method Than Experimental Results Due To The Absence Of Solvent Effects In Computational Methods. In Addition, The Effects Of Solvents And Concentrations On The Photophysical Properties Of Lvf And Nrf Were Investigated Using Uv/Vis Absorption And Fluorescence Spectroscopic Techniques. The Results Indicate That, The Quantum Yields, Fluorescence Life Time, Rate Of Radiative, And Non Radiative Decay Of The Drugs Were Affected By Solvent Polarity And Concentration Of The Sample. Also, The Binding Interaction Mechanism Of Lvf-Caffeine And Nrf-Caffeine Were Determined Using Fluorescence Quenching Method. From Fluorescence Quenching Spectral Analysis, The Quenching Rate Constant( )Qk , Binding Constant( )Ak, And Thermodynamic Parameters Were Determined In Different Temperatures. The Result Obtained Indicates That The Binding Between The Drugs And Caffeine Occurs Spontaneously In Which Electrostatic Force In Lvf-Cf, Hydrogen And Van Der Waals Force In Nrf-Cf, Play Major Role In The Reaction.