Novel Aggregation-induced Emission Luminogens With Heteroatoms: Design,synthesis,structure-property Relationship And Application

Over the course of the last 20 years,the field of aggregation-induced emission(AIE)research has been booming.Diverse AIE luminogens have been developed,providing abundant molecular models for fundamental science and numerous opportunities for novel functional materials.Amongst,the introduction of heteroatoms plays a significant role for the diversification and functionalization of AIE luminogens.This dissertation firstly reviews the structures,properties and mehanisms of some representative heteroatom-containing AIE systems,and enumerates some novel applications.Based on the current progress,folded tetraphenylethylene(TPE)derivatives and phosphindole oxide(PIO)derivatives are adopted in present studies.From the perspectives of steric effects and electronic effects,a variety of heteroatoms/heterocycles are introduced into these systems purposefully to study the effects of heteroatoms/heterocycles on structures and properties.Based on these systems,structure-property relationships are established,photophysical(and photochemical)mechanisms are explored,and potential applications in optoelectronic devices and biotechnology are expanded,to provide valuable guidance for the fundamental research and application development of AIE.Specifically,it includes the following two aspects:1)A series of TPE-based foldamers containing heteroatoms are developed.And various types of intramolecular benzene-benzene or benzene-aromatic(fused)heterocycle stacking models in TPE-based foldamers are successfully constructed.A molecular orbital decomposition analysis method of hybrid conjugate system is proposed to demonstrate the regulating effect of stacking models on hybrid conjugate structures.In addition,the photophysical properties and transition nature of these TPE-based foldamers are studied systematically to uncover the impact of conjugation structures.These works show great significance for understanding and exploring of multi-dimensional functional molecules.And the potential applications of these TPE-based foldamers are also displayed.2)A series of PIO derivatives containing heteroatomic substituents with different electron-donating or accepting properties are developed.On one hand,the structure-property relationships between substituents and photophysical properties of these PIO derivatives are studied.Based on these,a theoretical system based on the “quinoid transformation”mechanism in the excited state is established to explain their photophysical behaviors in solutions.And a mechanism of “restriction of quinoid transformation” is proposed to explain their AIE attributes.In addition,the potential application of these PIO derivatives in optoelectronic devices is also demonstrated.On the other hand,a kind of novel pure organic Type I-based photosensitizers is designed,whose photophysical and photochemical mechanisms are fully analyzed.A comprehensive study protocol on Type I-based photosensitizers is presented in both theoretical and experimental aspects.Further in vitro and in vivo evaluations of the Type I-based photosensitizers for the endoplasmic reticulum stressmediated photodynamic therapy against tumors are conducted,in which potential values of the biological effects are highlighted.Lastly,a series of cationic PIO derivatives with different lipophilicity are designed to regulate the penetrability and toxicity toward cells and bacteria.And a non-cellular invasive antibacterial agent has been screened,which demonstrates the importance of alkyl chain engineering in the design and development of small molecule antimicrobial agents.