Preparation And Properties Of Coin Metal Clusters Protected By Amino Acid-derived Ligand

Chirality is a fundamental property of matter and a reliable way of storing and transferring information,and chiral stimulation behaviour plays an extremely important role in the life sciences,materials science and medicine.For example,one of the key steps in the DNA transcription process is the conversion of DNA macromolecules from B-to Z-types under certain pH stimulation,thereby facilitating DNA unspin and replication.In addition,due to the extensive nature of chirality,chiral modulation of the system using external stimuli allows for simple and rapid writing or erasure of stimulus-responsive material informatio.Chiral stimulus response has potential applications in the fields of chiral catalysis,circularly polarised luminescence and chiral recognition.Although the research on chiral material stimulus response has developed rapidly in recent years,the research in this field is still in its infancy and there are still many problems that need to be solved in terms of mechanism and application.One of the greatest challenges is to design and synthesise chiral molecules with simple and precise chemical structures,and to construct chiral stimulus response materials with fast response time,good stability,high sensitivity,high cycle times and long life.Chiral coin-metal clusters can be studied at the atomic level to investigate the mechanism of stimulus response due to their atomically precise structures.In addition,literature research has revealed that chiral ligand-induced strategies can be used to construct atomically precise chiral coin-metal clusters in a simple and efficient manner.Therefore,chiral coin-metal clusters with stimulus response have attracted the attention of many researchers as a novel stimulus-responsive material with potential applications and are expected to become ideal chiral stimulus-responsive materials.Based on the above,in this paper,we use chiral amino acid-derived ligands,which are inherently chiral,economical and cheap raw materials,simple to synthesise and can modify different groups,to achieve the construction of chiral coin metal nanoclusters in one step and to examine their stimulus-responsive behaviour.The specific work is as follows:一.Firstly,a one-pot reaction of the chiral amino acid-derived ligand(S)-5-((R)hydroxyethyl)-3-phenyl-2-thioxoimidazolin-4-one(L1)/(R)-5-((5)-hydroxyethyl)-3phenyl-2-thioxoimidazolin-4-one(D1)with silver salts was designed and synthesized,successfully yielding a pair of atomically precise chiral silver metal clusters Ag6(L/DC11H12N2Os)6(L/D-Ag6-1C,C for crystal).The ligand-metal-metal charge-transfer leap confers yellow photoluminescence emission to L/D-Ag6-1C crystals.The circular dichroism(CD)spectrum of the crystalline enantiomer exhibits a strong kardon effect and a good mirror relationship in the range of 260-450 nm.The excellent luminescence properties also confer a strong circularly polarised luminescence signal(CPL)to the clustered crystalline pair.Interestingly,we found that L/D-Ag6-1 C did not luminesce in DMF solution,but gradually regained bright yellow luminescence after adding different volumes of undesirable solvent water,and L/D-Ag6-1C exhibited the typical aggregation-induced luminescence(AIE)phenomenon.With increasing levels of undesirable solvent water,the CPL signal at 560 nm gradually appears to be enhanced,with aggregation effectively triggering the CPL response in solution state,and interestingly,the signal is opposite to the CPL signal in the crystalline state.Similarly,the main absorption peak of the CD spectrum at 300 nm flips with increasing water content(fw≥ 50%).Overall,this work provides a theoretical basis and experimental foundation for the application of metal nanoclusters in the field of aggregationtriggered CD/CPL stimulation response functions.二.We have successfully constructed a pair of atomically precise chiral coppermetal clusters Cu4(L/D-C12H13N2OS)4(L/D-Cu4L4).L/D-Cu4L4 has a twisted tetrahedral Cu4 core protected by four ligands at the periphery.The enantiomers exhibit mechanically abrasive responsive properties,with the colour of mechanically abrasive samples changing from white to yellow accompanied by the appearance of photoluminescence,which can also be recovered through the solvent,making them a dual stimulus responsive material.Furthermore,based on the chiral nature of the clusters,the enantiomers show a CPL signal at 550 nm when the crystal is stimulated by mechanical grinding,enabling CPL switching.This work opens up a new avenue for understanding the application of copper metal clusters in sensing.