Construction and Application of Chiral Supramolecular Coordination-based Self-assembly Materials

Author:Li Zuo

Supervisor:liu wei sheng


Degree Year:2019





Chirality is the signature of nature and living system.The chirality at molecular and supramolecular levels is closely related to chemistry,physics,biology and materials.Coordination-driven self-assembly provides infinite possibilities for the construction of a mass of novel chiral coordination-based supramolecular materials,and make great progresses in asymmetric catalysis,nonlinear optics and chiral single-molecule magnets,etc.Lanthanide have attracted extensive attention due to their potential applications in optics,electricity and magnetism.However,the research on the chiral lanthanide supramolecular materials is still rare,and the controllable preparation of chiral lanthanide supramolecular materials with specific functions is still challenged.In this thesis,three pairs of chiral ligands derived from natural mandelic acids and lactic acids were designed and synthesized,respectively.After self-assembly with lanthanide ions,a series of chiral lanthanide complexes and chiral metallogels were prepared.Then,further researches were performed on their self-assembly process and applications.This paper was divided into the following six parts:(1)In this section,the research background of supramolecular chemistry was briefly introduced,and the application of polynuclear complexes and chiral complexes in various aspects was reviewed in detail.And then,the supramolecular gel was briefly introduced.(2)A pair of chiral ligands derived from natural mandelic acids was used to construct homochiral s-f triple-stranded helicates,and selective-Na+bonding was realized through cooperative effect in self-assembly processes.This work provides a way to distinguish Na+from other biologically important metal ions by supramolecular self-assembly processes and provides new insights for identifying Na+.(3)Radii-controlled self-assembly was realized in the processes of mandelic acid-derived chiral ligands self-assembly with La3+and Dy3+ions:La3+ions induced chiral trinuclear structure,but the smaller Dy3+ions formed chiral pentanuclear complexes.Crystal structure analysis and CD spectra confirmed that chiral transfer happened in the self-assembly process and give rise to the chiral self-assembled structures.Then,the magnetic properties of the chiral pentanuclear complexes were studied and the results demonstrated that it exhibits typical single-molecule magnet behavior.(4)By controlling the pH,two pairs of different enantiomeric complexes were prepared by using the same chiral ligands assembly with La3+ions.Under weak base conditions,a pair of enantiomeric dinuclear lanthanide complexes were obtained,but under strong base conditions,a pair of enantiomeric polynuclear s-f clusters were obtained.These chiral s-f clusters were nanosized and were the first chiral high-nuclear s-f cluster to date.Meanwhile,the chiral polynuclear s-f complexes can effectively recognize Asn from other natural amino acids through changes in chiral signals,it is the first example of Asn recognized by metal complexes.(5)A series of chiral lanthanide hydrogels were prepared through a pair of chiral lactic acids-derived gelators.It was found that the formation and stability of these lanthanide metallogels was closely related to the radius of lanthanide ions.As the radius decreases,the metallogel becomes more and more unstable,and the morphology of the xerogel changed significantly with the decrease of the ionic radius.Furthermore,the effective in-situ preparation of single crystals for various chiral transition metal complexes was achieved by adding transition metal ions to the metallogels,and then these transition metal complexes were characterized in detail.(6)In this section,we explored the fluorescent recognition of amino acids by chiral zinc complexes prepared by the above methods.In water solution,the zinc complexes can distinguish His and Cys from other natural amino acids,while in acetonitrile solution,the zinc complexes can perform efficient enantioselective discrimination for enantiomers of Leu,Met,Val and Phe.