Chiral Aggregation And Chemical Sensing Based On Peryleneisimide Dyes

Chirality is a basic characteristic of living organisms and nature.Molecular self-assembly plays an important role in biological systems,the transformation and storage of genetic information in nucleic acids,and the folding of proteins into efficient molecular machines.Supramolecular chirality originates from self-assembly of biomolecules during the abovementioned biological processes,being the consequence of a specific spatial arrangement of molecules.Chirality at a supramolecular level has attracted much attention due to rapid developments in supramolecular self-assembly.By taking advantage of their superior packing ability based on the ?-conjugated scaffold,perylene bisimide dyes can be aligned by chiral species into supramolecualr aggregates with a fixed spatial orientation.As a result,PBI dyes are important structural motifs for studying supramolecular chirality.In this thesis,the boronic acid and aldehyde functionalized PBI dyes were employed as building blocks to establish the supramolecular polymeric systems based on host-guest recognition for the sensing of L-DOPA and the determination of the enantiomeric excess of amino acids.Meanwhile,we reasonably built supramolecular polymeric systems exhibiting the unusual "anti-majority-rules effect".Key to achieving this rarely observed profile was the proper use of meso-species.This dissertation consists of five chapters.Chapter 1 onlines the properties and aggregation behavior of PBI dyes,optical detection methods for enantiomeric excess and sensing schemes based on induced supramolecular aggregation/disaggregation.Chapter 2 introduces an accurate method based on induced aggregation of PBI dyes for the determination of the enantiomeric excess of amino acids.An achiral intermediate,acting as a bridge between the amino acid analyst and boronic acid functionalized PBI dye PBIProBA,was introduced into the system.The chiral inducer,the product of reaction between the achiral intermediate and amino acids,was shown to be able to induce the aggregation of PBIProBA,giving rise to a strong Cotton effect in the PBI chromophore absorption region.Due to the strong Cotton effect related to the ee of the amino acids,the system can be applied to determinate the ee of amino acids using circular dichroism spectroscopy.At the same time,linear discriminant analysis was successfully employed for common amino acids.This method provided a novel strategy for high-throughput screening of chiral compounds.In chapter 3,meso-tartrate was introduced into the process of aggregation of boronic acid functionalized PBI dye PBIProBA,which enabled to construct a rare"anti-S-type" CD-ee relationship(i.e,the "anti-majority-rules effect").The important role of mesomer in constructing the "anti-majority-rules effect" was clarified through a variety of characterization methods.In chapter 4,a bilateral asymmetric PBI dye was designed,containing both a boronic acid and an aldehyde group at N-terminus of the PBI core.The boronic acid group interacted with the cis-diol moiety of L-DOPA,while the aldehyde group formed imine bond with the amine group of L-DOPA.The electrostatic repulsion between dye molecules and the hydrophilicity of boronic acid groups that prevent the aggregation of the dyes were therefore overcome,promoting the aggregation of PBI dye.The CD-based sensing of L-DOPA at a micromlar concentration level was successful,due to the efficient synergistic effect during the occurring aggregation.