Synthesis, characterization and crystal structures of oxidovanadium(V) complexes derived from hydrazone ligands with antibacterial activity

A pair of new oxidovanadium(V) complexes, [VOL¹(OEt)(EtOH)] (1) and [VOL²(OEt)] (2), where L¹ and L² are the dianionic form of 3-fluoro-<i>N’</i>-((2-hydroxynaphthalen-1-yl)methylene)benzohydrazide (H₂L¹) and 4-bromo-<i>N’</i>-(2-hydroxy-3-methoxybenzylidene)benzohydrazide (H₂L²), respectively, were prepared and characterized by elemental analysis, infrared and electronic spectra, and ¹H NMR spectra. Structures of the complexes were further confirmed by single crystal X-ray determination. The V atom in complex 1 is in octahedral coordination, and that in complex 2 is in square pyramidal coordination. Both hydrazone ligands coordinate to the V atoms through the phenolate O, imino N, and enolate O atoms. In complex 1, one ethanol and one deprotonated ethanol ligands coordinate to the V atom, while in complex 2, only one deprotonated ethanol ligand coordinates to the V atom. The complexes show effective antibacterial activity against <i>Bacillus subtilis</i>. Complex 1 has the most active activity against <i>B. subtilis</i>, with IC₅₀ value of 1.77 µg mL⁻¹, which is comparable to that of Penicillin G.

本研究合成了一对新型氧化钒(V)配合物[VOL¹(OEt)(EtOH)]（1）与[VOL²(OEt)]（2），其中L¹与L²分别为3-氟-N’-((2-羟基萘-1-基)亚甲基)苯甲酰肼（H₂L¹）与4-溴-N’-(2-羟基-3-甲氧基苯亚甲基)苯甲酰肼（H₂L²）的二阴离子形式。通过元素分析、红外光谱、电子光谱及氢核磁共振（¹H NMR）光谱对上述配合物进行了表征，并借助单晶X射线衍射进一步确证了配合物的晶体结构。配合物1中的钒原子采取八面体配位构型，而配合物2中的钒原子则为四方锥配位构型。两种腙配体均通过酚氧原子、亚胺氮原子与烯醇氧原子与钒原子配位。配合物1中，1分子乙醇与1个去质子化乙醇配体与钒原子配位；而配合物2中仅存在1个去质子化乙醇配体与钒原子配位。该系列配合物对枯草芽孢杆菌（Bacillus subtilis）均表现出优异的抗菌活性，其中配合物1的抗菌活性最优，其半数抑菌浓度（IC₅₀）为1.77 μg·mL⁻¹，活性可与青霉素G（Penicillin G）相媲美。