Supramolecular Chirality Regulation And Application Based On Steroid Aromatics Clathrates And Deep Eutectic Solvents

At present,the research on chirality at supramolecular level has attracted extensive attention.Different from molecular chirality,supramolecular chirality is the formation of chiral or achiral building elements through non-covalent interactions,which can be defined as the asymmetric stacking of molecules in space.Precise regulation of supramolecular chirality and its chiral optical properties is critical for understanding homochirality in nature and constructing chiral materials.However,many challenges remain,such as the transfer amplification of chirality in crystalline co-assembly and the conduction of chirality between solvents and assemblers.Aiming at these two problems,this paper carries out the following two parts of paper:1.Design and properties of chiral materials of steroid-aromatics clathrates with circular polarization luminescence and phosphorescenceSteroid molecule is a natural compound with inherent chirality,which can produce strong CH-π interaction with aromatic compounds in solid state.In this work,steroid progesterone(Pg)as the main molecule and a variety of aromatic compounds as the guest molecule were used to study the chiral transfer between host and guest.By means of single crystal structure analysis and infrared spectroscopy,we prove that there are two modes of interaction between host and guest molecules:"channel type" and "cavity type".Circular dichroism and circular polarization luminescence spectra were used to confirm the transfer of chiral to achiral aromatic objects.In addition,based on the structure of guest molecules,it is found that some host-guest complexes exhibit interesting luminescence properties.For example,a complex of Pg and the AIE molecule tetraphene(TPE@Pg)achieves circularly polarized luminescence with the AIE effect.Using the rigid environment of the main molecule Pg and the heavy atomic effect of bromine atoms,circularly polarized phosphorescence emission has been successfully achieved in the complexes PyBr@Pg or NapBr@Pg formed between Pg and 1-bromopyrene or 2bromonaphthol.In addition,panchromatic luminescence can be achieved by changing the guest molecules.This work reveals that steroidal aromatic compounds have great potential in the design and application of multifunctional chiral materials.2.Chiral transfer in deep eutectic solventsDeep eutectic solvents(DESs)is a kind of eutectic mixture whose melting point is lower than its component.It is an emerging environmentally friendly solvent for the preparation of functional aggregates and nanostructures.Solvent environment is an important factor in the construction of supramolecular chirality.In this work,β-cyclodextrin and choline chloride were used as hydrogen bond acceptors,and three chiral carboxylic acids were used as hydrogen bond donors.Through multiple hydrogen bonds and electrostatic interactions,various chiral DESs were prepared.A series of achiral organic small molecules with nitrogen heterocyclic rings were selected as solutes,and chiral DESs was used as solvent to explore the chiral induction and transfer between DESs and achiral small molecules.The existence of multiple hydrogen bonds and π-π stacking was confirmed by infrared spectroscopy and powder X-ray diffraction.Circular dichroism spectra further demonstrated that solute molecules PB-3 and PB-5 could generate significant chiral optical signals through chiral transfer in the DESs system,and corresponding micro-nano structures were also observed by scanning electron microscopy and transmission electron microscopy.DESs has significant selectivity for the chiral control of the assembly.Solute molecules must have strong binding ability with small carboxylic acids in DESs.This work realizes solvent-solute chiral transfer in DESs and provides a powerful way to construct new functional chiral assembly materials.