Construction Of Supramolecular Architectures Based On Donor-acceptor Interaction

Supramolecular chemistry focuses on weak and reversible non-covalent interactions between molecules.These weak and reversible interactions(non-covalent bonds)are important to understand biological system and self-assembly systems,as well as,to building complex materials.Among them,materials based on donor-acceptor interactions have been widely used as solar cells,liquid crystals,organic semiconductor materials and light-emitting diodes due to their electrochemical properties.A particularly attractive feature of non-covalent bonds is adaptability and responsiveness to external stimuli based on its weak and reversible interactions.Due to the special properties of non-covalent bonds,supramolecular materials based on non-covalent interactions can respond to external environmental stimuli,thus showing unique and excellent properties,such as good mechanical properties,self-healing and stimulus response.Although many researchers focus on donor-acceptor supramolecular system,the reported system rarely involves the complex switchable system based on donor receptor interactions.It is well known that pyrene is an electron donor molecule,which can interact with other electron acceptors to form charge-transfer complexes(CT complexes).Here we introduced an amphiphilic donor molecule,which was composed of hydrophobic pyrene segments and hydrophilic D-mannose segment,in which two segments were connected by oligoethylene glycol linker through a click reaction.The amphiphilic donor molecule formed a series of CT complexes through donor-receptor interactions with electron acceptors in aqueous solution.The research of this thesis includes the following two chapters:1.Dissipative supramolecular chiral sheets by chemical fuel through donoracceptor interactionsIn this chapter,we reported dissipative supramolecular chiral two-dimensional(2-D)structure driven by 7,7,8,8-tetracyanoquinodimethane(TCNQ)as a chemical fuel through donor-acceptor interactions between pyrene based amphiphilic molecule and TCNQ.In the presence of TCNQ as an acceptor,non-assembling precursor(donor)could self-assemble into sheet structures.The resulting chiral sheets driven by TCNQ showed intense circularly polarized luminescence(CPL)signals with a large luminescence dissymmetric factor(glum)value.The supramolecular chiral sheets are spontaneously disassembled when TCNQ reduces to its divalent anion.The subsequent additions of TCNQ as chemical fuel drive the disassembled molecules to repeatedly form optically-active sheet structures,demonstrating that the optically-active materials transiently exist only as far as TCNQ fuel is supplied.These unique 2-D chiral materials may provide new insights for functional chiral dissipation systems.2.Construction of supramolecular architectures based on donor-acceptor interactionsIn this chapter,we used pyrene based amphiphilic molecule synthesized in chapter 1 with other electron deficient receptors to construct CT complexes in aqueous solution through donor-acceptor interaction to study the influence of donor-acceptor interaction further.Pyrene based donor molecule can co-assemble with other acceptor molecules 2,4,5,7-tetranitro-9-fluorenone(TNF),4,5,7-trinitro-9-oxofluorene-2-carboxylic acid(TNC)and trinitrobenzene(TNB)to form nanotoroid,pH-responsive nanotoroid and nanofiber in aqueous solution,respectively.After replacing one nitro group of TNF with a carboxyl group to form TNC,the CT complex was formed by donor molecule and acceptor molecule TNC.In low pH,the CT complex shows toroid structure in the aqueous solution.However,the toroid structure will gradually open to form nanofiber with the length of several micrometers when the pH increases.The supramolecular structures of CT complexes were changed by adjusting electron acceptors,demonstrating that the structure of the CT complexes is affected by the structure of the electron acceptors.The synthesis of supramolecular polymer will provide a new insights for the construction of supramolecular materials with switchable function.