Construction And Functionalization Of ?-Conjugated Supramolecular Assembly Systems

?-conjugated supramolecular assemblies,which are formed by non-covalent assembly.Due to the unique responsiveness to external stimuli such as chemical,mechanical stress,light,and vapor,they have been widely used in organic optoelectronics,bioimaging,photocatalysis,and information security.Currently,most of the commonly building blocks used for ?-conjugated supramolecular assemblies are aromatic hydrocarbons,oligo(p-phenylene vinylene),naphthalene diimide and perylene bisimide derivatives,while other ?-conjugated units have rarely been reported.On the other hand,the structural parameters of building blocks,the synergistic assembly of multiple non-covalent bonds,and the introduction of novel non-covalent bonds on the macroscopic properties of supramolecular assemblies,are still in the exploratory stage.In addition,compared to a multi-component supramolecular assembly system having a specific spatial arrangement of chlorophyll in nature,the composition of artificial supramolecular assemblies is relatively simple,which results in the lack of responsiveness to functional integration and external stimuli.In view of the above problems and challenges,we have been working to explore the novel driving force and building motifs of ?-conjugated supramolecular assembly,the correlation between monomer parameters and assembled functions,and the multi-component assembly and function.In the first part,a rod-like platinum(?)acetylide monomer with a less bulky ligand has been designed and synthesized,which is prone to form helical nanofibers and organogels via a cooperative nucleation-elongation mechanism,whilst no aggregation can be detected for the bulky counterpart,thus demonstrating the significant role of ligand effects on the macroscopic supramolecular polymerization behaviors.This work lays a good foundation for us to study the application of such platinum(?)acetylide supramolecular assemblies in the field of ? functional materials.In the second part,by taking advantage of multicycle anthracene-endoperoxide switching properties,a ?-conjugated supramolecular assembly with visible light responsiveness has been constructed with cooperative nucleation-elongation mechanism,which facilitate fluorescence resonance energy transfer(FRET)process via two-component co-assembly strategy.The FRET efficiency can be delicately regulated by either light-triggered anthracene-endoperoxide conversion or vapor-induced monomer-assembly transition,leading to high-contrast fluorescent changes among three different states.On this basis,dual-mode anti-counterfeiting patterns have been successfully fabricated via inkjet printing techniques.In order to explore the application of ?-conjugated supramolecular assemblies in the field of information storage and security,in the third part we construct a vapofluorochromic supramolecular assemblies based on the dicyanodistyrylbenzene moiety.Thus,the fluorescent color code patterns possess encryption/decryption functions is printed,thereby realizing the secure and reliable protection of coding information.In the fourth part,trimethylammonium-derived alkynylplatinum(?)terpyridine molecular tweezers have been designed and synthesized.Due to the synergistic interaction of Pt(?)…Pt(?)metal-metals and donor-acceptor interactions,they show moderate binding affinity towards the complementary organoplatinum guest in polar media.Responsive guest encapsulation/release from the cavity of molecular tweezers can be achieved by successive addition and removal of trifluoroacetic acid,accompanying with remarkable switching of the photophysical signals,which would benefit for the fabrication of intelligent supramolecular materials with tailored functionalities.In the last part,a novel long-range ordered supramolecular alternating co-assembly has been developed by incorporating Pt(?)...Pt(?)metal-metal interaction for the hetero-complexation process.The co-assembly possesses a metal-metal-to-ligand charge transfer(MMLCT)absorption band in the visible-light region,which can be further applied for low-energy visible-light photo-catalysis that is unattainable for the individual species.Interestingly,"on-demand" photo-catalytic efficiency can be achieved by manipulating the reversibility of the supramolecular co-assembly process.This research work provides a novel model system for understanding the intrinsic relationship between the molecular structure of the building blocks,the controllable arrangement of the ?-conjugated assembly,and the functionality of the supramolecular assembly materials.