Synthesis,Structure And Properties Of Chiral Poly-copper Clusters

Because of the chiral separation of structure,the orderly accumulation of chiral molecules,all kinds of covalent bonding supramolecular interactions within in the molecules and electron configuration of metal elements and chemical properties etc.,chiral polymetallic clusters are potential applications in single molecule magnet magnetic materials,the performance of ferromagnetic and ferroelectric coexistence of multiferroic materials,new catalyst,nonlinear optical materials,and other fields.However,not only a few chiral polymetallic clusters have been explored so far,but also the research about its properties and application still need further development.Therefore,rational design and synthesis of such compounds with multifunctional properties have very important significance.In this context,we carry out“Synthesis,structure and properties of chiral poly-copper clusters”as the theme of the paper.The main research purpose of this paper is to explore the synthesis,self-assembly rule of chiral poly-copper clusters,and the relationship between structure and performance.In order to provide a precursor for the development of new type of multifunctional materials,we focus our research on synthesis,structure and properties of chiral poly-copper clusters,resulting in three series of poly-copper clusters including enantiomers[Cu₈]and enantiomers[Cu₂₄]₂ clusters,[Cu₇]and[Cu₂]copper-oxygen clusters.The specific content are described as follows:?1?Through the "chiral ligands guiding" method,enantiomers[Cu₈]clusters?1and 2?were synthesized by using enantiomer ligands L-and D-tartaric acid.The pair enantiomers[Cu₈]_n clusters were with three-dimensional layered supramolecular structure.To investigate the chiroptical activities of these two compounds,the Circular Dichroism?CD?spectra of both compounds in the solid and solution state were measured.To investigate the stability of both compounds dissolved in p H=5.5Na OAc/HOAc buffer solution,the Small Angle X-ray Scattering?SAXS?,Scanning Electron Microscope?SEM?,Atomic Force Microscope?AFM?and Ultraviolet Visible spectra?UV/Vis?of complex 2 in the solution were measured.These studies revealed that complexes 1 and 2 were 2D-layered structure of[Cu₃₂]_n exist in solution.And this gave a hint on illustrating its self-assembly rule:four[Cu₈]substructure units connected by four carboxyls of four tartrate to form a windmill[Cu₃₂^II]tetramer,the adjacent[Cu₃₂^II]tetramer connected by common[Cu₈]substructure units to form a2D-layered structure,and these 2D-layered structures connected by the hydrogen bonds between tartrate and guanidine cationic group[C?NH₂?₃]⁺to formed 3D-layered supramolecular structure.In compounds 1 and 2,the bridging way of the guanidine cationic group[C?NH₂?₃]⁺was novel,showing that its structure diversity.Using it as a structure-directing agent to synthesise multidimensional supramolecular structure of clusters is an efficient method.Magnetic study indicated that between the Cu-Cu ions in compounds 1 and 2,there were three kinds of communication and requiring three coupling constants to fit.Compounds 1 and 2 demonstrated antiferromagnetic interaction.?2?By using rac-antimony potassium tartrate to bridge Cu ions,we obtained a copper-oxo cluster with flat structure[Cu₇]?3?and a copper-oxo cluster with cage structure[Cu₂]?4?.We did the precision control of the synthesis conditions,and we found that synthetic conditions on the successful synthesis of compoun d 3 and 4 were very important.In the synthesis process,it was very critical to introduce K₂CO₃.The role of K₂CO₃ was not only to control p H value,but also to accommodate the coordination ability of tartaric acid ligand with Cu²⁺and Sb³⁺.As the review said,this synthetic method to obtain polynuclear metal-oxo cluster anionic compounds by introducing K₂CO₃ will be of great significance for inorganic chemistry and polyoxometalate field.Antimony potassium tartrate could hydrolysis in the synthesis system to form two kinds of scaffold to brigde metal ions.This comfimed the p H value was important factor during the synthesis of metal-oxo clusters.Magnetic study indicated that between the Cu-Cu ions in compounds 3,there were five kinds of communication and requiring five coupling constants to fit.Complex 1 demonstrated significant ferromagnetic interaction with an S=7/2 spin ground state.Complex 2demonstrated weak ferromagnetic with an S=2/2 spin ground state.?3?Based on the "chiral ligands guiding" method,enantiomers[Cu₂₄]₂ clusters?5and 6?were synthesized by using enantiomer ligands L-and D-tartaric acid.The pair enantiomers[Cu₂₄]₂ clusters were with 3D porous supramolecular structure.Accompany with the chiral poly-copper clusters,we obtained a new type of carbon oxygen anion C₆O₁₀^6-and octahedral Cu₂O microcrystalline.To investigate the chiroptical activities of these two compounds,the CD spectra of both compounds in the solid and solution state were measured.To investigate the stability of both compounds dissolved in aqueous solution,the SEM,UV/Vis,Dynamic Light Scattering?DLS?,Zeta potential of both compounds in aqueous solution were measured.These studies were comfirmed that complexes 5 and 6 were stable in aqueous solution.By using Elemental Analysis?EA?,Inductively Coupled Plasma?ICP?and X-ray Photoelectron Spectroscopy?XPS?,we determined that the content of elements included Cu,Na,P,C,H,O and the valence of Cu ion was+2 in compounds5 and 6.Magnetic study showed that compounds 5 and 6 demonstrated strong antiferromagnetism interaction.¹³C NMR and single crystal structure analysis confirmed that the new type of carbon oxygen anion C₆O₁₀^6-existed in the chirality of copper clusters.Cu₂O microcrystalline had an octahedral shape which was determined by the XRD and SEM analysises.