Phthalocyanine And Dipeptide Multi-Dimensional Self-Assembly Regulation

Choosing different building blocks and regulating a variety of non-covalent interactions(?-? stacking and hydrogen bonding,etc.)can obtain an orderly structured supramolecular self-assembly that exhibits excellent new characteristics which monomers do not have.Chirality is one of the essential attributes of materials with different scales.Supramolecular chirality plays an important role in supramolecular assembly.By regulating the supramolecular assembly systems,the nanostructure revolution,chiral transmission and amplification can be realized.It is of great significance for exploring the methods and principles of the structure and chiral regulation in supramolecular assemblies,and further deepening the understanding the changes of complex systems in nature and the interactions among molecules.Phthalocyanine molecules with large conjugated plane structure can exhibit a variety of physical and chemical properties by changing peripheral substituents and central coordination metals;dipeptide molecules can form supramolecular hydrogels with good stability and biocompatibility through hydrogen bonding and electrostatic interaction.At present,phthalocyanine and dipeptide molecules have attracted much attention in the research fields of supramolecular self-assembly and supramolecular chirality due to their high degree of tunability and wide field of application.In this paper,we select single-and double-decker phthalocyanines with different substituents and diphenylalanine peptide modified with N-fluorenylmethoxycarbonyl(Fmoc-FF)as the research objects.The structure and chiral regulation of double-decker phthalocyanine assemblies within 2D Langmuir-Bologett(LB)film and phthalocyanine/dipeptide co-assemblies in 3D hydrogel system were studied by various assembly and regulation methods.The magical phenomena and new properties produced in supramolecular self-assembly was explored.Including phthalocyanines into other supramolecular assembly systems,especially into the biocompatible 3D supramolecular hydrogel systems can be important.Few octacarboxyl zinc phthalocyanine complex {Zn[Pc(COOH)8]}(Pc)molecules have been mixed with a large number of Fmoc-FF to explore the effect of phthalocyanine planar conjugated molecules on Fmoc-FF assembly.After adding a small amount of Pc,the secondary structure of Fmoc-FF assemblies changed largely with the emerging of Helix.Based on the regulating of few Pc molecules on the hierarchical assembly of Fmoc-FF secondary structures,the changes from fiber structure to the long-ordered helical nanotubes can be achieved.Importantly,these nanotubes show a strong circularly polarized luminescence(CPL)properties with great asymmetry factor(glum=0.04).It is suggesting that the co-assemblies of few Pc molecules with Fmoc-FF can realize the structural revolution,chiral reorgnazation and excited state chirality amplification of Fmoc-FF assembly.These results provide new ideas for regulating the generation of the helical structure and supramolecular nanotubes with CPL characteristics by a small amount of cofactors.Although the noncovalent interactions between Fmoc-FF and Pc are quite weak,few Pc molecules still has a huge impact on the Fmoc-FF assembly.On the other hand,there is no chiral transformation from Fmoc-FF to Pc.As an excellent supramolecular hydrogel building unit,Fmoc-FF has a strong application potential in flexible materials and bioengineering.Therefore,Fmoc-FF assembly was used as a chiral host,and a small amount of achiral Rhodamine B(RhB)molecules are added as a guest.Through chiral transformation,a supramolecular hydrogel with CPL in the visible light region was prepared.At the same time,changing buffer solution of Fmoc-FF assemblies,successfully altered the nanostructures of Fmoc-FF assemblies,and regulated the supramolecular chirality as well as excited state chirality of RhB assemblies.This result expands the way for the regulation of flexible optical materials.At the 2D air/water interface,the study on symmetry breaking of achiral double-decker phthalocyanine based on LB technology is an urgent need.In this paper,the structure and chirality of LB and Langmuir-Schaefer(LS)films formed by the self-assembly of achiral cerium double-decker phthalocyanine containing sixteen short alkoxy chains molecule(Ce(Pc 1)₂)have been studied by LB technology at the air-water interface.Ce(Pc 1)₂ LB films can achieve symmetry breaking under high surface pressure,resulting in supramolecular chirality.Most interestingly,the corresponding supramolecular assembly within the solid-state can be reorganized with the formation of helical nanostructures and amplification of Cotton effect upon keeping at the room temperature and atmospheric pressure.The experimental results show that the the double-decker phthalocyanines substituted by alkoxy chains exhibits excellent characteristics in the regulation of the nanostructures and chirality of 2D self-assembly,and provides a new perspective for the regulation of supramolecular assemblies.Although supramolecular self-assemblies have been extensively studied,there are still few researches on supramolecular assembly of ?-conjugated molecules containing complex aromatic substituents.The LB technology has been used to study the supramolecular assembly of double-decker cerium and yttrium phthalocyanines containing sixteen phenol substituents(Ce(Pc2)₂ and Y(Pc2)₂).It is found that the double-decker phthalocyanines are assembled in a special stacking manner at the air-water interface to form a neatly arranged nanoparticles,and the nanostructure of the self-assemblies can be completely controlled by adjusting the surface pressure.This research result opens up a new way for the supramolecular assembly of complex ?-conjugated systems.In summary,the co-assembly or self-assembly of various phthalocyanines and Fmoc-FF was used to successfully achieve nanostructure regulation and chiral amplification in 2D film and 3D hydrogel assemblies,which provides new ideas and insights for supramolecular assembly structure and chirality control.