调控发色团手性物理环境构筑高性能圆偏振发光材料

Constructing high performance circularly polarized luminescence materials by regulating the chiral physical environment of chromophores

圆偏振发光材料由于其特殊的手性发光性质,在信息加密、不对称催化、光电器件、生物传感等方面受到广泛的关注.圆偏振发光材料的传统构筑方法通常需要复杂的合成,并且发光不对称因子glum较难提高,很难满足实际应用.通过调控发色团的手性物理环境来构筑圆偏振发光材料具有制备方法简单、适用性强的优点,同时可以兼容各种手性或非手性发色团,且其发光不对称因子普遍较高,为圆偏振发光材料的实际应用提供了可能.自下而上(bottom-up)的自组装技术是通过改变发色团手性物理环境来增强和放大手性光学信号的非常有效的策略,是圆偏振发光材料最常用的构筑策略.另一方面,得益于纳米加工技术的发展,自上而下(top-down)的人工超表面也成为通过改变发色团手性物理环境来构筑高效圆偏振发光材料的新方法.自组装技术具有动态可逆的优点,而超表面手性结构的构筑策略在精细调控材料微观结构方面更具优势.本文介绍了基于手性物理环境调控的圆偏振发光材料的构筑策略,综述了圆偏振发光的相关概念,总结了自组装和超表面两种方法构筑高性能圆偏振发光材料的研究进展,以及手性物理环境调控的圆偏振发光材料在信息加密、生物传感和不对称光聚合方面的应用.

Circularly polarized luminescence (CPL) materials, due to their special chiral luminescence properties, have attractedwidespread attention in information encryption, asymmetric catalysis, optoelectronic devices, and biosensing. Traditionalmethods for preparing CPL materials often require complex and tedious synthesis processes. Besides, it is difficult toenhance the luminescence dissymmetry factor (glum) and meet practical applications. Constructing CPL materials bymodulating the chiral physical environment of chromophores has the advantages of simple preparation and strongapplicability, compatible with various chiral or achiral chromophores, and generally having large luminescencedissymmetry factor, providing the possibility of practical applications of CPL materials. Self-assembly, a bottom-upconstruction method, is a common strategy to change the chiral physical environment of chromophores. Chiral selfassemblyrefers to the phenomenon where assembly elements accumulate into asymmetric structures through one or morenon-covalent interactions. There are three possible situations: (1) The chiral chromophore can form a chiral structurethrough self-assembly, and significantly enlarge CD and CPL;(2) for the achiral chromophore, it can generally assemblewith other chiral materials to form a chiral assembly structure by asymmetric stacking arrangement and obtain CPLperformance;(3) the completely achiral chromophore can also generate chirality and CPL performance by symmetrybreaking during assembly. The non-covalent interactions usually have strong modularity and dynamic modulation ofperformance can be achieved through reasonable design, which is suitable for constructing the intelligent responsive CPLmaterials. Besides, thanks to the development of nanofabrication technology, the artificial metasurface, a top-downconstruction method, has also become a new method to construct efficient CPL materials by changing the chiral physicalenvironment of chromophores. There are two mechanisms for CPL in metasurfaces: Firstly, the chiral electromagnetic fieldgenerated by the metasurfaces can change the spin state of emitted light, leading to spontaneous circularly polarized lightemission;the second is that chiral metasurfaces can selectively absorb or reflect circularly polarized light of a certainchirality, thereby enhancing circularly polarized luminescence of another chirality. Artificial metasurfaces are typicallycomposed of one or more layers of artificially designed nanostructures so the thickness of metasurfaces is always small.What’s more, it also has advantages in controlling material structures. Thanks to these advantages, CPL materialsmodulated by the chiral physical environment of chromophores have a lot of applications. However, there are still someproblems in this kind of material, for example, the low glum factor in self-assembly and there is only a small number ofexamples of CPL metasurfaces. In this review, based on the construction strategy of CPL materials modulated by the chiralphysical environment of chromophores, we introduce the relevant concepts of CPL, summarize the research progress ofconstructing high-performance CPL materials by self-assembly and metasurfaces, and the application of CPL materials ininformation encryption, biosensing, and asymmetric photopolymerization, and propose the current problems and theprospect.