Department of Chemistry, Faculty of Science, Zagazig University, Zagazig 44519, Egypt.
Department of Basic Science, Higher Future Institute of Engineering and Technology, Mansoura 35511, Egypt.
Int J Mol Sci. 2022 Jul 20;23(14):8019. doi: 10.3390/ijms23148019.
Coumarin is highly distributed in nature, notably in higher plants. The biological features of coumarin include antibacterial, anticancer and antioxidant effects. It is well known that metal ions present in complexes accelerate the drug action and the efficacy of organic therapeutic agents. The main aim of the current study is the synthesis of different complexes of the interaction between ciprofloxacin hydrochloride (CIP) and coumarin derivative 7-hydroxy-4-methylcoumarin (HMC) with Zr(IV). The chelates of CIP with Zr(IV) were prepared and characterized by elemental analysis, melting point, conductance measurements, spectroscopic techniques involving IR, UV-Vis, H NMR, and thermal behavior (TG-DTG) in the presence of HMC, dimethylformamide (DMF), pyridine (Py), and triethylamine (EtN). Results of molar conductivity tests showed that the new synthesized complexes are electrolytes with a 1:1 or 1:2 electrolyte ratio, with the chloride ions functioning as counter ions. According to IR spectra, CIP acts as a neutral bidentate ligand with Zr(IV) through one carboxylato oxygen and the carbonyl group, HMC as a monodentate through the carbonyl group, and DMF through the oxygen atom of the carbonyl group and the N atom of Py and EtN. The thermal behavior of the complexes was carefully investigated using TG and DTG techniques. TG findings signal that water molecules are found as hydrated and coordinated. The thermal decomposition mechanisms proposed for CIP, HMC, and Zr(IV) complexes are discussed and the activation energies (E), Gibbs free energies (∆G*), entropies (∆S*), and enthalpies (∆H*) of thermal decomposition reactions have been calculated using Coats-Redfern (CR) and Horowitz-Metzeger (HM) methods. The studied complexes were tested against some human pathogens and phytopathogens, including three Gram-positive bacteria (, , ) and three Gram-negative bacteria (, and ), and compared to the free CIP and HMC parent compounds.
香豆素在自然界中分布广泛，特别是在高等植物中。香豆素的生物学特性包括抗菌、抗癌和抗氧化作用。众所周知，金属离子存在于配合物中可以加速药物作用和有机治疗剂的疗效。目前研究的主要目的是合成不同的配合物，研究盐酸环丙沙星（CIP）与香豆素衍生物 7-羟基-4-甲基香豆素（HMC）与 Zr（IV）的相互作用。通过元素分析、熔点、电导率测量、光谱技术（包括 IR、UV-Vis、H NMR 和热行为（TG-DTG））制备和表征 CIP 与 Zr（IV）的配合物，在 HMC、二甲基甲酰胺（DMF）、吡啶（Py）和三乙胺（EtN）存在下。摩尔电导率测试结果表明，新合成的配合物是具有 1:1 或 1:2 电解质比的电解质，其中氯离子作为抗衡离子。根据 IR 光谱，CIP 作为一种中性双齿配体与 Zr（IV）通过一个羧基氧和羰基，HMC 作为单齿通过羰基，DMF 通过羰基的氧原子和 Py 和 EtN 的 N 原子。使用 TG 和 DTG 技术仔细研究了配合物的热行为。TG 结果表明发现了作为水合和配位的水分子。讨论了 CIP、HMC 和 Zr（IV）配合物的热分解机制，并使用 Coats-Redfern（CR）和 Horowitz-Metzeger（HM）方法计算了热分解反应的活化能（E）、吉布斯自由能（∆G*）、熵（∆S*）和焓（∆H*）。研究了这些配合物对一些人类病原体和植物病原体的作用，包括三种革兰氏阳性菌（、、）和三种革兰氏阴性菌（、和），并与游离 CIP 和 HMC 母体化合物进行了比较。
