Study On The Interaction And Bacteriostatic Activity Of Quinazoline And Coumarin Derivatives With Heavy Metal Ions

Heavy metal pollution has an important impact on the ecological environment and human health.Therefore,the basic research on the selective identification and detection of metal ions is of great significance.The organic fluorescence probe has high sensitivity,good selectivity,simple operation and easy synthesis.It is a research hotspot in the field of metal ion detection.Therefore,to design new organic ligands,to synthesize new metal complexes,to understand the interaction between organic molecules and metal ions,will provide the necessary theoretical support for the design of high performance ion recognition materials.This paper designed and synthesized a variety of quinazoline and coumarin organic ligands,the interaction mechanism is studied by interacting with metal ions such as Cu²⁺,Ni²⁺,Co²⁺and so on.The bacteriostaticl activities of them against Gram-positive/negative bacteria were also investigated.1.Three kinds of quinazoline type ligands HL¹-HL³ were synthesized by reacting o-aminoacetophenone oxime as intermediate 1 with 2-pyridinecarboxaldehyde,3-ethoxy salicylaldehyde,and 4-methoxy salicylaldehyde,respectively:HL¹:2-?2-pyridyl?-4-methyl-1,2-quinazoline-N³-oxide;HL²:2-?3-ethoxy-4-phenolic hydroxy?-4-methyl-1,2-quinazoline-N³-oxide;HL³:2-?4-methoxy-2-phenolic hydroxy?-4-methyl-1,2-quinazoline-N³-oxide.Then,using elemental analysis,¹H NMR and IR to determine the structure of quinazoline organic ligands.2.In the methanol solution,the naked eye recognition of metal ions such as Mg²⁺,Zn²⁺,Cd²⁺,Cu²⁺,Ni²⁺,Co²⁺,Ba²⁺,Mn²⁺,Hg²⁺and Pb²⁺with HL¹ were investigated,and Cu?II?complex 1 was obtained by natural evaporation method with Cu?NO₃?₂?3H₂O.The structure of 1 was determined by elemental analysis,IR,X-ray single crystal diffraction.The UV–Vis and bacteriostatic activity of 1 were compared with HL¹,and the electrochemical properties of1 was also studied.In addition,the electronic structure of 1 was optimized by density functional theory?DFT?,and the HOMO,LUMO energy and band gap values were calculated;the effect of electronic transition on the UV–Vis absorption spectrum was further elucidated by the time-dependent density functional theory?TD-DFT?simulation of UV–Vis;the intermolecular interaction of 1 was quantified by Hirshfeld surface analysis.3.In the methanol solution,the naked eye recognition of metal ions such as Zn²⁺,Cd²⁺,Cu²⁺,Mg²⁺,Ni²⁺,Ba²⁺,Mn²⁺,Hg²⁺and Co²⁺with HL² were investigated,and complexes 2–4were obtained by natural evaporation method with Cu?OAc?₂?H₂O,Ni?OAc?₂?4H₂O and Cu?NO₃?₂?3H₂O.The structure of 2–4 were determined by elemental analysis,IR,X-ray single crystal diffraction.The UV–Vis and bacteriostatic activity of 2–4 and the fluorescence spectrum of 3 were compared with HL².The electrochemical properties of 2–4 and the electron paramagnetic resonance spectroscopy?EPR?of 4 were also investigated.In addition,the complexes 2–4 were theoretically studied using DFT calculations,TD-DFT calculations,and Hirshfeld surface analysis.4.In the methanol solution,the naked eye recognition of metal ions such as Mg²⁺,Zn²⁺,Cu²⁺,Co²⁺,Cd²⁺,Ni²⁺,Ba²⁺and Mn²⁺with HL³were investigated,and Co?II?complex 5 was obtained by natural evaporation method with Co?NO₃?₂?6H₂O.The structure of 5 was determined by elemental analysis,IR,X-ray single crystal diffraction.The UV–Vis and bacteriostatic activity of 5 were compared with HL³,and the electrochemical properties of 5were also studied.In addition,the complex 5 was theoretically studied using DFT calculations,TD-DFT calculations,and Hirshfeld surface analysis.5.The coumarin derivatives HL⁴and HL⁵were synthesized by reacting coumarin-3-hydrazide as intermediate 2 with imidazole-2-formaldehyde and pyridine-4-carbaldehyde,respectively:HL⁴:2-oxo-N'-??1H-imidazol-2-yl?methylene?-2H-chromene-3-carbohydrazide;HL⁵:2-oxo-N'-?pyridin-4-ylmethylene?-2H-chromene-3-carbohydrazide.Then,using elemental analysis,¹H NMR and IR to determine the structures of coumarin organic ligands.The interactions between HL⁴,HL⁵and heavy metal ions such as Mg²⁺,Zn²⁺,Cu²⁺,Co²⁺,Cd²⁺,Ni²⁺,Ba²⁺and Mn²⁺were analyzed by the naked eye recognition and UV–Vis absorption spectroscopy,their bacteriostatic activity were also tested.