Design,Construction And Properties Of Chiral Supermolecular Tweezering Systems

Chirality is indispensable for living life.By employing various non-covalent interactions,chiral molecules can construct diverse chiral supramolecular structures with various structures and functions,thus realizing the chiral transfer from molecular to supramolecular level.However,it is difficult to analyze the chiral supramolecular structure in biological system due to highly complexity.Accordingly,it is urgent to develop artificial chiral system to mimic the chiral transfer mechanism in life system.Platinum(?)-based molecular tweezers are supramolecular hosts with flexible conformation and tunable complexation ability.Among them,th e planar tridentate Pt(?)complexes are typical chromophores with unique photophysical and chemical properties.On this basis,we designed two different Pt(?)-based molecular tweezers to realize the chiral transfer from molecular to supramolecular level via non-covalent tweezering recognition.In the meantime,the relationship between supramolecular structure and chirality during the chirality transfer was carefully investigated as well.The detailed research works are divided into the following two parts.In the first part of the works,we designed and synthesized a non-chiral molecular tweezers with "pre-organization effect",which can recognize chiral guest and form tweezering complexes with unique spatial orientation.In combination with theoretical computations,we investigated the relationships between conformational changes and chirality transfer in tweezering system.In particular,the tweezering system showed excellent solvent and temperature tolerances because of the synergistic non-covalent interactions.Additionally,we also investigated the relationship between hierarchical assembly behaviors and chirality amplification in aqueous media.It is interesting to note that,by using the rapid coordination between Pt(?)pincers and phenyl isonitrile,we realized the induction of supramolecular chirality signals in the three-component system.In summary,this part of the research has opened up a new avenue for the architecture of artificial supramolecular chiral systems with excellent environmental tolerance.In the second part of the works,we have designed and prepared a novel V-shaped chiral molecular tweezer,which associates with guest molecules to form sandwiched tweezering complexes via participation of Pt(?)---Pt(?)interactions.The effects of conformational changes on chirality transfer and chirality amplification in tweezering recognition were studied by monitoring UV-Vis absorption and CD spectral changes,together with the influences of solvent-and temperature-dependent behaviors on the induction of supramolecular chirality.Theoretical computations further confirmed that the tweezering structure is of vital importance for supramolecular chirality transfer.Besides,by constructing amphiphilic tweezering systems,we realized chiral transfer in aqueous media,which showed significantly discrepancies with respect to chirality induction behaviors in organic solvents.To sum up,this part of the research works provides new ideologies for the rational construction of chiral supramolecular systems with specific structures and tailored functions.