| Metal ions are widely existed in life,not only an important part of industrial production,but also some metal ions are necessary trace elements in human body.However,excessive metal ions will accumulate and migrate when entering the ecosystem,causing heavy metal pollution.Meanwhile,excessive metal ions entered the ecosystem will accumulate and migrate,heavy metal pollution mainly originates from industrial pollution,through wastewater,waste residue into the soil as well as rivers,enrichment in human body,animals and plants,thus affecting human body and environment.Metal ions are easily chelated with some functional groups,which can lead to conformational changes or denaturation of proteins in the human digestive system,and the lack of trace elements can also affect the development of bone tissue and internal organs.Therefore,rapid and quantitative detection of metal ions has become a research hotspot for researchers.Salen-based compounds and their derivatives are an indispensable part of coordination chemistry.They can coordinate with metal ions to form stable complexes.Based on the excellent characteristics of salen-based compounds,salamo-based compounds have been developed on this basis,salamo-based compounds have a unique N2O2 cavity,significantly improve their stabilities,form more stable complexes after coordination with metal ions,and have good application prospects in the fields of optical materials,magnetic materials,and chemical catalysis.First,an asymmetric salamo-based ligand(H2L1)was synthesized and structurally characterized.When DMF/H2O(9:1)was used as the solvent,H2L1 showed a high selective recognition effect on Cu2+.Using DFT theoretical calculations,it was found that H2L1 could form a more stable complex(1:1)with Cu2+,and the calculated minimum limit of detection(LOD)of H2L1 for Cu2+is 2.01×10-7 M,the binding constant is K=1.36×109 M-1.In addition,H2L1 could be used to identify B4O72-under the same detection conditions,and the calculated minimum limit of detection(LOD)for the identification of B4O72-is 9.96×10-7 M,the binding constant is K=3.72×108 M-1.By the action of EDTA,H2L1 has the ability to recognize the cycling of Cu2+and shows a better response in the physiological p H range,and the H2L1 is characterized by fast and efficient recognition.In addition,H2L1 test paper of Cu2+and B4O72-were studied and the recognition effect is more obvious.Meanwhile,the H2L1 can be used to quantify Cu2+and B4O72-in water samples.Secondly,a novel asymmetric salamo-based ligand(H2L2)was synthesized and structurally characterized.H2L2 exhibits efficient dual-channel recognition of Cu2+and B4O72-under DMF:H2O=9:1 solvent conditions.Among them,the oxime nitrogen and phenolic oxygen atoms in H2L2 can be used as binding sites for Cu2+.Further calculations and titration results showed that H2L2 can bind to Cu2+to form a 1:1 complex,which in turn leads to fluorescence quenching.While the introduction of B4O72-,the density of the electron clouds around the N and O atoms changed,which can prompt H2L2 to produce stronger fluorescence.The minimum limit of detection(LOD)of H2L2 for Cu2+is 1.99×10-7 M,the binding constant is K=1.37×109 M-1 and that for B4O72-is 7.57×10-7 M,the binding constant is K=2.17×109 M-1.In addition,H2L2 also has the characteristics of fast recognition speed and high efficiency.Meanwhile,H2L2 is also used to detect the content of Cu2+and B4O72-in different water samples.At the same time,the strip for rapid identification of Cu2+and B4O72-has been studied.Finally,single crystals of the ligand H2L2 were obtained and reacted with Cu(Cl O)4·6H2O to obtain a rare binuclear complex 1[Cu2(L2)2].In the complex 1,one oxygen atom on the oxime group participates in the coordination,this is different from the previously reported copper(II)complexes.Then,the ligands H2L1 and H2L2,Ni Cl2·6H2O and auxiliary ligand Na N3 were used to obtain novel multinuclear nickel(II)complexes 2 and 3.Considering the characteristics of the ligands,the ligand H2L3 was synthesized,and the same synthetic method was used to obtain the complex 4.It is worth noting that the structures of the complexes 2-4 contain unclosed cubic configuration,Among them,the complexes 2-4,respectively:[Ni4(L1)2(N3)4(Me OH)2]?CH3COCH3(2),[Ni4(L2)2(N3)4(Me OH)2]?4CH3COCH3(3),[Ni4(L3)2(N3)4Cl(Me OH)3]·CH3COCH3(4),Subsequently,the structures and properties of the ligands and the obtained complexes were studied systematically.Ligand H2L2:C21H20N2O5,Mr=380.39,Monoclinic,space group C1 2/c1;Complex 1:C42H36Cu2N4O10,Mr=883.83,Monoclinic,space group P 21/C;Complex 2:C40H49N13Ni4O14,Mr=1170.76,Triclinic,space group P-1;Complex 3:C57H71N13Ni4O17,Mr=1445.10,Monoclinic,space group P 1 21/c1;Complex 4:C42H53Cl N10Ni4O16,Mr=1224.23,Triclinic,space group P-1. |
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