To construct p-molecules with dfferent structures is one of the key points in the research field of opto-electronic materials. In many cases, the molecular structure not only affects the intramolecular-conjugation, but also the intermolecular p-p stacking, to result in the different functionalities. In this talk, some typical examples will be presented to partially demonstrate the interesting different properties with minor or even ignorable structural difference.

Self-Assembly of amphiphilic polymers in water is promising to create precise yet dynamic micelles, hydrogels, and nanostructured materials. Recently, we have developed self-assembly systems of amphiphilic random or alternating copolymers carrying hydrophilic groups and hydrophobic groups as side chains in water or bulk/film state.In this paper, we report recent advances on the self-assembly of amphiphilic random/alternating copolymers as new strategies to create controlled aggregates and soft materials as follows: Precision self-assembly into micelles in waterTypically, amphiphilic random copolymers bearing poly(ethylene glycol) (PEG) and alkyl groups self-fold and/or intermolecularly assembled via the association of the hydrophobic groups into unimer or multichain micelles in water. The random copolymer micelles are approximately 10 nm and smaller than general block copolymer micelles. The size and aggregation number of the micelles can be controlled by the composition, degree of polymerization, and side chains. (2) Dynamic self-sorting micelles and hydrogels. Binary mixtures of different random copolymers form discrete multichain micelles via the self-sorting of their polymer chains or fused micelles via the co-self-assembly of the polymers. Those micelles further induce dynamic yet selective exchange of the polymer chains. Self-healing and selectively adhesive hydrogels can be prepared using such dynamic random copolymer micelles as physical crosslinking units.(3) Microphase separation into nanostructured materials. Amphiphilic random copolymers further induce pendant microphase separation into nanostructured materials/films.

In this lecture, I will present our study on the principles of AIE[1] and the horizons of materials science. I was fortunate to come across a new AIEgen, 9,10-bis(dialkylamino)anthracene. In studying this photophysical process, I was able to understand the following principles of AIE. “The AIE phenomenon requires control of the non-radiative decay (deactivation) pathway, that is, controlling the conical intersection (CI) on the potential energy surface enables the formation of fluorescent molecules (CI high) and non-fluorescent (CI low) molecules separately.” Then, based on this principle, I designed a new AIEgen called bridged stilbene. These AIEgens have unique properties and have been applied beyond AIE to the development of advanced materials.

Organic aggregate packing balances noncovalent interactions to control photoluminescence and ionic conductivity. We revealed how pressure tunes the packing and electronic structure of perphenyl chromophores, establishing structure–property relationships for rotor-like fluorophores. We also demonstrated counterion-controlled aggregation of ionic chromophores in solution. Furthermore, we designed diffusely charged aromatic cations that enable state-independent halide conductivity.

Our group has  also reported hypervalent  tin-fused azobenzene (TAz) compounds (Figure 1) [1‒3]. From a  series of mechanistic  studies, it has been  clarified that the  coordination of the N  atom to the tin atom and  the electron donation  from the O atom to the π-  system simultaneously  caused stabilization of the lowest unoccupied molecular orbital energy level and  elevation of the highest occupied molecular orbital energy level, achieving a narrow  energy gap. Moreover, TAz can formed stable higher-coordinated structures, which  changed the electronic state and the absorption and emission wavelengths. However,  the planar structure of the π-planes of TAz caused critical aggregation-caused  quenching. In this study, we attempted to give excitation-driven property to hypervalent  tin compounds to develop aggregation-induced emission molecules showing emission  in the longer wavelength region only in the solid state [4]. We focused on azomethine  structure, which allows to be introduced substituents at the C=N position. The steric  hindrance originating from the substituent causes distortion in the molecule and  promotes intramolecular vibration. Based on this idea, we designed and synthesized  three types of hypervalent tin-fused azomethine compounds with different substituents (H, Me, and Ph) and explored researched the differences in optical properties derived  from the substituents. Furthermore, we attempted to application to thermal sensors  using the polymers containing the hypervalent tin-fused azomethine units compounds  in the backbone.