| In recent years,scientific researchers have made more and more deep research on functional complexes,not only because of their easy-to-control structure,but also their excellent properties in light,electricity,and magnetism.This work mainly carried out the synthesis,structure and properties of transition metal complexes with Schiff base framework ligands.Six transition metal complexes were synthesized by natural volatilization.The main contents are as follows:Firstly,choosing 4-aminoacetophenone as the substrate,reacting with ethoxyhydroxylamine hydrochloride and 3,5-bromosalicylic aldehyde to obtain the schiff base ligand HL1 of the ethoxy oxime.Three transition metal complexes were obtained by the reaction of the ligand and cobalt(?)acetate tetrahydrate,zinc(?)acetate dihydrate and silver(?)nitrate[Co(L1)2](1),{4[Zn(L1)2]·CH2Cl2}(2)and[Ag(HL1)(NO3)]n(3).Among them,the complex 3 is an one-dimensional chain-like structure infinitely extended,which is a coordination polymer.In each polymerization unit,the central atom Ag(?)is a five-coordinate twisted triangular bipyramid configuration.The crystal structures of complexes 1 and 2 are similar,they are both 1:2(M:L)complexes,and the central atoms Co(?)and Zn(?)are all four-coordinated twisted tetrahedral configurations.The properties of complexes 1-3 were studied,and it was found that the fluorescence intensity of complex 3 at the excitation wavelength is 369 nm was significantly lower than that of the ligand HL1 and the complexes1 and 2.Therefore,the optical properties of the complex 3 should be further studied,which can explore the potential of complex 3 as a fluorescent material.The weak intramolecular interactions of complexes 1-3 were quantified by Hirshefield surface analysis and DFT theoretical calculations.They proved the stability in the air of the complexes 1-3.Secondly,2-amino-3-benoxypyridine and 3,5-dichlorosalicylic aldehyde were used to react to obtain the ligand HL2 with a Schiff base skeleton.Then using the ligand react with copper(?)acetate monohydrate to obtain the complex[Cu(L2)2](4).It is found that the central atom copper(?)of complex 4 is in a six-coordinate twisted octahedral configuration.The properties of complex 4 were studied,and it was found that the result The properties of complex 4 were studied,and result measured by single crystal X-ray diffractometer is consistent with that of the ultraviolet titration spectroscopy.In addition,the experimental and theoretical values of the frontier molecular orbital energy gap of complex 4 are obtained through combining combining the C-V curve,UV-visible absorption spectrum and DFT theoretical calculations.There is a certain deviation between the experimental and theoretical values which can be attributed into the influence of the C-V curve measurement and the solvent used in the UV-visible spectrum measurement process,or the system error of the instrument during the measurement process.Thirdly,selected the substrate 4-aminoacetophenone,O-allyl hydroxylamine hydrochloride and 3,5-dibromosalicylic aldehyde to react to obtain O-allyl oxime Shiff base ligand HL3.Then using this ligand,cobalt(?)acetate tetrahydrate and zinc(?)acetate dehydrate to react to obtain two transition metal complexes{4[Co(L3)2]·CH2Cl2}(5),{4[Zn(L3)2]·CH2Cl2}(6).The structures of complexes 5 and 6 are similar,and they are both 1:2(M:L)type complexes,and the central atoms Co(?)and Zn(?)are both twisted tetrahedral with four-coordinate.In addition,the properties of complexes 5 and 6 are studied,and it is found that complex 5 has a significant effect on reducing the fluorescence intensity of the ligand,and its optical properties can be further explored.The DFT theoretical calculation,Hirshefield surface analysis and PXRD analysis proved that both complexes 5 and 6 exist stably in the air,and the purity of the samples obtained through experiments is high relatively.Lastly,the application of the ligand HL3 as a fluorescence sensor to identify Fe3+was studied.The coordination mode and ratio of HL3 and Fe3+were determined by the ultraviolet titration and fluorescence titration,as well as the previous work of our research group.In addition,the recognition mechanism of HL3 to Fe3+has been explored.As we all know,the Fe3+has the ability to abtain electronics easily,when it is combined with HL3,a ligand-to-metal charge transition(LMCT)occurs,that is,a PET effect from the ligand to Fe3+,which leads to the quenching of HL3 fluorescence.Therefore,we speculate that the recognition mechanism of HL3 to Fe3+is light-induced electron transfer. |
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