| Heavy metal salts play an important role in industrial production,but due to their toxicity,they can cause serious environmental pollution.At the same time,heavy metal ions will chelate with proteins,denature proteins.The digestion and absorption of protein in the body is done by amino acids.As the first nutrient element in the body,its role in food nutrition is obvious,but it cannot be directly used in the human body,but through it is used after it becomes a small molecule of amino acid.As people’s attention to health and quality of life continues to increase,researchers are working to develop a quick and easy way to detect these heavy metal ions,while also enabling continuous identification,which has been recycled.Due to the low cost and fast response of fluorescence detection technology,the design and synthesis of high selectivity and sensitivity fluorescent chemical sensors has received much attention in the fields of biochemistry and environmental science.Salen and its derivatives（R–CH=N–（CH2）n–N=CH–R）are essential Schiff bases in coordination chemistry and have received wide attention in the past few decades.They can coordinate with alkaline earth ions,rare earth ions and d-block transition metal ions to form stable mononuclear or polynuclear metal coordination compounds.In recent years,based on the study of salen and its derivatives,a new important class of salamo-based ligands and their derivatives have been developed（R–CH=N–O–（CH2）n–O–N=CH–R）.The holes formed by N2O2-donor are more easily combined with metal ions,have better stability and flexibility than the former,and complexes formed with transition metal ions in optical materials,electrochemistry,catalysts,antibacterial activities,porous materials,and single-molecule magnets and many other fields have good application prospects.First,a monoterpene compound was designed and synthesized by using1,2-bis（aminooxy）ethane and 2-hydroxy-3,5-dichlorobenzaldehyde,and further purified by column chromatography to obtain a half-salamo-based ligand HL1.First,ligand HL1recognizes Pb2+as a fluorescent chemical sensor and continuously recognizes cysteine（Cys）.HL1 forms a complex L1-Pb2+by binding with Pb2+,and a new fluorescence emission peak appears to achieve recognition of heavy metal Pb2+ions.The formed complex L1-Pb2+further recognizes Cys to achieve Pb2+binding in the Cys and L1-Pb2+complex,releasing the sensor molecule HL1.Through their fluorescence changes,we analyzed the corresponding recognition mechanism.At the same time,it laid a theoretical foundation for studying the application of this simple half-salamo-based sensor HL1 in the actual environment.Similarly,an unanticipated[Cu2（L2）2]（1）complex was obtained by reacting the half-salamo-based ligand HL1 with transition metal salt Cu（OAc）2·H 2O,which is a newly synthesized by cleavage.The salamo-based ligand HL1 is formed by the chelating ligand H2L2.It was characterized by elemental analysis,infrared spectroscopy,ultraviolet-visible spectroscopy and fluorescence spectroscopy,single crystal X-ray diffraction analysis and Hirshfeld surface analysis.Secondly,the self-made 1,2-bis（aminooxy）ethane and 2-hydroxy-naphthaldehyde are reacted to obtain 2-[O-（1-ethyloxyamide）]oxime-2-naphthol,which is purified by column chromatography.Then,it was further reacted with 2-hydroxy-5-methyl-1,3-benzenedialdehyde to obtain a bissalamo-based tetraoxime ligand H3L3,and single crystal of the ligand H3L3 was obtained.The ligand reacts separately with transition metal salts to obtain two homonuclear transition metal complexes[Co2（L3）NO3]（2）and[Cu4（L3）2（H2O）2]·2ClO4（3）.The metal complexes were characterized to determine the regularity and spatial configuration of the syntheses.The corresponding fluorescence properties,Hirshfeld surface analysis and antibacterial activity were systematically studied.Finally,according to the previous report,2,3-dihydroxy-1,4-naphthalene dialdehyde was synthesized through five reaction steps,which reacted with4-（1-ethyl-propyl）-2-[O-（1-ethyloxyamide）]oxime-2-hydroxyphenol to obtain a bissalamo-based tetraoxime ligand H4L4,which was reacted with copper（II）acetate.The five corresponding 3d-4f heteronuclear complexes 4-8 are as follows:[Cu2Ce（L4）（NO3）3]（4）,[{Cu2Y（L4）（μ2-NO3）（NO3）2MeOH}{Cu2Y（L4）（μ2-AcO）（NO3）2}]（5）,[{Cu2Sm（L4）（μ2-NO3）（NO3）2MeOH}2]·2CH3OH（6）,[{Cu2Gd（L4）（μ2-NO3）（NO3）2MeOH}2]·2CH3OH（7）,[{Cu2Tb（L4）（μ2-NO3）（NO3）2H2O}{Cu2Tb（L4）（μ2-AcO）（NO3）2}]（8）,the crystal structures of these complexes were systematically characterized.Complex 1:C32H20Cl8Cu2N4O8,Mr=999.22,Triclinic,space group P-1;Ligand H3L3:C35H32N4O7,Mr=620.64,Triclinic,space group P-1;Complex 2:C35H29Co2N5O10,Mr=797.49,Monoclinic,space group P2 1/c;Complex 3:C70H62Cl2Cu4N8O26,Mr=1756.38,Triclinic,space group P-1;Complex 4:C38H42Cu2CeN9O17,Mr=1164.00,Monoclinic,space group P2 1/n;Complex 5:C79H91Cu4Y2N17O34,Mr=2206.573,Triclinic,space group P-1;Complex 6:C40H49Cu2SmN9O19,Mr=1237.34,Monoclinic,space group C1 2/c1;Complex 7:C80H100Cu4Gd2N18O38,Mr=2490.43,Monoclinic,space group C1 2/c1;Complex 8:C78H84Cu4Tb2N18O34.78,Mr=2402.11,Triclinic,space group P-1;... |
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