Tarek A Yousef1,2, Essam Ezzeldin3,4, Hatem A Abdel-Aziz5, Mohamed H Al-Agamy6,7, Gamal A E Mostafa3,5. 1. College of Science, Chemistry Department, Imam Mohammad Ibn Saud Islamic University (IMSIU), Riyadh 11623, Kingdom of Saudi Arabia. 2. Department of Toxic and Narcotic Drug, Forensic Medicine, Mansoura Laboratory, Medicolegal Organization, Ministry of Justice, Mansoura, Egypt. 3. Department of Pharmaceutical Chemistry, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia. 4. Bioavailability Laboratory, Central Laboratory, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia. 5. Applied Organic Chemistry Department, National Research Center, Cairo 12622, Egypt. 6. Department of Pharmaceutics, College of Pharmacy, King Saud University, Riyadh 11451, Saudi Arabia. 7. Department of Microbiology and Immunology, Faculty of Pharmacy, Al-Azhar University, Cairo, Egypt.
Abstract
BACKGROUND: Electron donor-acceptor interactions are important molecular reactions for the activity of pharmacological compounds. The aim of the study is to develop a charge transfer (CT) complex: synthesis, characterization, antimicrobial activity, and theoretical study. METHOD AND RESULTS: A solid CT complex of neostigmine (NSG) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was synthesized and characterized by infrared spectra, NMR, and UV-visible spectroscopy. The results confirm the formation of a CT complex. The stability of the CT complex between NSG and DDQ in acetonitrile was determined in solution via spectrophotometric measurement, ie, by calculating the formation constant, molar extinction coefficient, and different spectroscopic parameters. The stoichiometry of the formed NSG-DDQ complex was determined using Job's method. The absorption band of the NSG-DDQ complex can be used for the quantification of NSG. CONCLUSION: The DFT geometry optimization of NSG, DDQ, and the CT complex and the UV comparative study of both theoretical and experimental structures are presented. The experimental results confirm the charge transfer structure. The bacterial study shows that the NSG-DDQ complex has good antibacterial activity against both Gram-positive and Gram-negative bacteria as well as antifungal activity against Candida albicans.
BACKGROUND: Electron donor-acceptor interactions are important molecular reactions for the activity of pharmacological compounds. The aim of the study is to develop a charge transfer (CT) complex: synthesis, characterization, antimicrobial activity, and theoretical study. METHOD AND RESULTS: A solid CT complex of neostigmine (NSG) with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was synthesized and characterized by infrared spectra, NMR, and UV-visible spectroscopy. The results confirm the formation of a CT complex. The stability of the CT complex between NSG and DDQ in acetonitrile was determined in solution via spectrophotometric measurement, ie, by calculating the formation constant, molar extinction coefficient, and different spectroscopic parameters. The stoichiometry of the formed NSG-DDQ complex was determined using Job's method. The absorption band of the NSG-DDQ complex can be used for the quantification of NSG. CONCLUSION: The DFT geometry optimization of NSG, DDQ, and the CT complex and the UV comparative study of both theoretical and experimental structures are presented. The experimental results confirm the charge transfer structure. The bacterial study shows that the NSG-DDQ complex has good antibacterial activity against both Gram-positive and Gram-negative bacteria as well as antifungal activity against Candida albicans.
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