Study On Copper(Ⅱ) Complexes Constructed By Bis(Salamo)-Type Compounds And Fluorescence Probes

Salamo-type compounds are widely used in metal organic and inorganic chemistry,due to their stronger chelating functions and stable structures.It has better development advantages and potential application values in materials,magnetism,catalysis,chemical sensors,etc.The coordination mode of a complex synthesized from Salamo-type ligand depends on many factors,such as the nature of the ligand,the radius of the central metal（II/III）atom,the type of solvent,anions,the ratio of solvent system used,and so on.In this thesis,salamo-type compounds H₃L¹and H₃L²and their corresponding copper（II）complexes were synthesized.In addition,The ion recognition of H₃L²and their complexes has been deeply studied.1.A symmetrical multidentate chelated salamo-type ligand H₃L¹was designed and synthesized.It was reacted with Cu Cl₂·2H₂O and Cu（NO₃）₂·3H₂O in ethanol（methanol）at a molar ratio of 1:3 to obtain four polynuclear Cu（II）complexes[Cu₂（HL）（Et OH）Cl₂]·CH₂Cl₂,[Cu₄（L）₂（Et OH）₂]（NO₃）₂·2Et OH（2）,[Cu₂（HL）Cl₂（Me OH）]·Me OH·2CH₂Cl₂（3）and[Cu₄（L）₂（Me OH）₂]（NO₃）₂·Et OH（4）.Complex 1 is a copper（II）dichloride complex synthesized from copper（II）chloride dihydrate as the starting material.Complex 2 has a central symmetric double helix structure.Compared to H₃L¹,due to the paramagnetic effect of the Cu（II）ion itself,it is easy to bind to the chelating group with an appropriate cavity volume,resulting in fluorescence quenching of complexes 1 and 2.In addition,Hirshfeld surface analysis was also used to determine intermolecular interactions in the crystal structures of complexes 1 and 2.The two Cu（II）atoms of complex 3 are connected through a phenol oxygen bridge and located in one cavity of the ligand,resulting in the absence of Cu（II）atom coordination in the other cavity.For complex 4,it has a completely deporotonated tetranuclear centrosymmetric structure.The anion effect is the reason for the significant differences in the structures of the complexes 3 and 4.Perhaps compared to the nitrate ion in complex 4,the chloride ion of complex 3 is more easily bound to the Cu（II）atom,which leads to a different structures of complexes 3 and 4.Through DFT calculation,it was found that the electron cloud densities of complexes 3 and 4 are more dispersed and the energy gaps are smaller than that of the ligand,indicating that the formed complexes 3 and 4 are more stable.The Hirshfeld surface and two-dimensional fingerprints were used to quantify different forms of intermolecular interactions in complexes 3 and 4.Finally,fluorescence spectra showed that complexes 3 and 4 have significant fluorescence quenching effects.2.A chlorine substituted bis（salamo）-type ligand H₃L²and its corresponding Cu（II）complex were synthesized,and a series of physicochemical characterization methods and Hirshfeld surfaces analyses were performed.Complex 5 belongs to a 2:4（L:M）structure,in which Cu1 and Cu2 atoms belong to five-coordinated twisted tetragonal pyramid geometries.The overall structure of complex 5 is centrally symmetric.In addition,Hirshfeld surface analysis showed that complex 5 is stable due to intramolecular hydrogen bond interactions.DFT calculations well demonstrated the electron transfer patterns of the ligand H₃L²and complex 5,which can also be used to explain the fluorescence quenching of copper（II）complexes.IRI mainly analyzes exhibited there are various interactions between the ligand H₃L²and complex 5,as well as the influence of steric hindrance.Similarly,complex 5exhibits a strong fluorescence quenching effect.3.A chemical sensor based on H₃L²fluorescent switch response mechanism was designed to recognize hydrogen phosphate ions.The experimental results confirmed that H₃L²exhibits significant fluorescence enhancement for Zn²⁺ions,which is likely due to the chelation-enhanced fluorescence（CHEF）effect.Therefore,L-Zn²⁺was chosed as an in situ complex sensor for the detection of hydrogen phosphate ions.According to the experimental results,the complex sensor L-Zn²⁺has a significant fluorescence quenching effect on hydrogen phosphate ions.This is due to the combination of hydrogen phosphate ions with Zn²⁺ions,which releases H₃L²and quenches the fluorescence.In addition,the sensor L-Zn²⁺has a good anti-interference ability for the detection of H₂PO₄^-ions,and in neutral and weak alkaline environments,the detection of the H₂PO₄^-ions reaches the micromolar level.The possible mechanism was verified by a series of mass spectrometry,UV-visible spectroscopy,fluorescence titration experiments,and DFT calculations.Finally,a simple qualitative identification using a test strip experiment indicated that this complex fluorescence sensor is expected to be applied in fields such as environmental detection.