Study On Design,Assembly,and Properties Of Salamo-based Fluorescent Sensors And Their Metal(Ⅱ) Complexes

With the continuous development of society and industry,people pay more and more attention to environmental protection and life safety.Therefore,it is particularly important to develop effective methods for the detection of organic pollutants,harmful ions and amino acids.As a new method of analysis and testing,fluorescent chemical sensors have the characteristics of simple operation,simple synthesis and high selective recognition.As a result,there has been a research boom in the fields of medicine,biochemistry and environmental monitoring.Salamo-based compounds are a new type of compounds developed on the basis of salen-based compounds by introducing oxygen atoms with high electronegativity,which have an O-alkyl oxime structure（–CH=N–O–（CH₂）_n–O–N=CH–）.Compared to salen-based compounds,the introduction of oxygen atoms makes the salamo-based compounds more stable.In this thesis,an asymmetric salamo-based sensor H2L was designed and synthesized as a chemical sensor for recognizing amino acid molecules.Based on the chemical sensor called H2L,Cu（II）complexes,Co（II）complexes,Zn（II）coordination polymer,Ni（II）coordination polymer and Cd（II）coordination polymers were synthesized through the introduction of auxiliary ligand strategies,then their crystal structures and sensing properties were studied.These studies provided an experimental basis for the design of novel,selective and highly sensitive sensors.1.A novel polyhalogenated asymmetric salamo-based fluorescence chemical sensor was designed and synthesized.After investigating the selective sensing of H2L to various amino acids through a full fluorescence scan,it was found that arginine can significantly enhance the fluorescence of H2L and has no interference with the recognition of arginine in the presence of other amino acids.The sensing mechanism of H2L toward arginine was studied by infrared spectroscopy and high-resolution mass spectrometry.The prepared fluorescence detection strip for H2L can conveniently and quickly detect arginine.2.Based on the asymmetric salamo-based fluorescence chemical sensor H2L,three complexes,Cu（II）complex（1）,Co（II）complex（2）and Zn（II）complex（3）,were synthesized by natural volatilization method.Due to the differences in coordination atoms and the introduction of auxiliary ligand strategy,the structural differences among the three complexes are relatively significant,complexes 1 and 2 do not form complexes consisting of 4,4?-bipy.Due to the intervention of auxiliary ligands,the complex 3 self-assembles to form a one-dimensional chain coordination polymer,then complexes 1,2 and 3 also form supramolecular structures ultimately through intermolecular interactions.In addition,the short-range interaction in the crystal structure was quantitatively analyzed by Hirshfeld surface analysis and 2D fingerprint,and the frontier molecular orbital energy of H2L and complexes 1,2 and 3 was calculated by density functional theory（DFT）.3.Based on the asymmetric salamo-based ligand H2L,a novel self-assembled Ni（II）coordination polymer（Ni（II）-CP）was prepared and characterized.By inserting an auxiliary ligand 4,4?-bipy,the constructed coordination polymer has a novel structure,forming an infinite one-dimensional chain like extension structure.The results of sensing performance experiments show that the sensor Ni（II）-CP can detect 4-NP and Cr₂O₇^2-ions with high selectivity and sensitivity.Cyclic experiments show that Ni（II）-CP has reversible detection performance for 4-NP and Cr₂O₇^2-ions.Based on FT-IR,UV-Vis spectroscopy experiments and DFT calculations,the possible mechanism of quenching the luminescence of the sensor Ni（II）-CP by 4-NP and Cr₂O₇^2-ions was investigated.4.Two Cd（II）coordination polymers（Cd（II）-CP¹ and Cd（II）-CP²）based on asymmetric salamo-based ligand H2L were assembled by inserting different auxiliary ligands4,4?-bipyridine（4,4?-bipy）and 1,4-bis（p-pyridyl）benzene（1,4-pbyb）.The structural diversity of coordination polymers was explored through X-ray single crystal diffraction experiments.The results of the luminescent sensing experiment and the anti-interference experiment indicate that Cd（II）-CP¹ and Cd（II）-CP² can selectively detect PA and S^2-.The possible recognition mechanism was analyzed through infrared spectroscopy,UV-Vis absorption spectroscopy and DFT calculations.In addition,Cd（II）-CP¹ and Cd（II）-CP² show good application prospects in the luminescence sensing of NACs and anions.