Design And Properties Of Perylene Diimides Containing Chiral Functional Groups

Chirality plays an important role in nature,and organisms are often highly selective for chiral molecules with enantiomers,such as D-sugars and L-amino acids,which make up organisms.In addition,specific chirality is of key importance in areas such as drug development,molecular recognition,and chiral sensing.Therefore,it is of great importance to study the supramolecular assembly behavior of molecular structures with specific chirality in solution and the effects of their assemblies on life activities from the perspective of chirality.In this paper,we use perylene diimide（PDI）,aπ-conjugated fluorescent molecule with excellent performance,as the core unit of assembly,and realize the modulation of PDI assembly behavior and the modulation of cellular uptake behavior of PDI nanoparticles by modifying different chiral groups at the imide position of PDI,more details are as follows:System 1:PDI derivatives（D/L-MAN-PDI）with D/L-mannose modification were designed and synthesized.The D/L-MAN-PDIs all formed uniformly shaped nanoparticles in the mixed solvent DMSO/H₂O,and the enantiomers were observed to have a spherical shape with a particle size of about 170 nm by SEM.In addition,combined with UV-Vis absorption and fluorescence spectrum,it was demonstrated that the aggregation state and fluorescence properties of the enantiomeric assemblies were highly similar and comparable.CD spectrum confirmed that the enantiomeric assemblies have different molecular chiral surfaces,but the chirality failed to be transferred to PDI via supramolecular assembly.Microplate reader and confocal microscopy studies revealed that MCF-7 cells were selective for the uptake behavior of the D/L-MAN-PDI assemblies and that the D-MAN-PDI assemblies were more and faster to be taken up by MCF-7 cells.Isothermal calorimetric titrations and molecular computational simulations revealed that both D/L-MAN-PDI assemblies were taken up by MCF-7 cells via active transport mediated by mannose receptor protein,but D-MAN-PDI assemblies were more strongly bound to the receptor protein.A comparative study of A549 cells without mannose receptor protein overexpression confirmed that exogenous L-mannose modified PDI assemblies could also promote cellular uptake through receptor-mediated active transport.This work,reveals the mechanism of receptor protein recognition of chiral materials and provides new ideas for controllable drug transporters.System 2:In the DMF/H₂O system,the supramolecular assembly behavior of chiral transfer occurred for both enantiomers D/L-MAN-PDI,but there were differences in their assembly pathways.UV-Vis absorption spectrum showed that the D-MAN-PDI assemblies could reach equilibrium and form thermodynamically stable J aggregates within 1 h,while it took 7 days for L-MAN-PDI to reach the J aggregates.The assembly pathway and process of J aggregate formation by D/L-MAN-PDI were revealed by the effect of different concentrations on the aggregation equilibrium rate.The kinetic study of the self-assembly process revealed that D-MAN-PDI could be accelerated to reach equilibrium by heating;while L-MAN-PDI could be accelerated to reach equilibrium by increasing the concentration and pre-sonication.Characterized by fluorescence spectrum and CD spectroscopy,it was found that thermally stable J aggregates have stronger fluorescence emission with chiral signals.Characterized by SEM,it was found that within 1 h,D molecules can form helical shaped assemblies and L-MAN-PDI form random blocky assemblies.This work,reveals the effect of chirality on the assembly pathway,provides a new idea for the construction of supramolecular assemblies.