基于AIE效应的转光剂的设计、合成、转光性能及作用机制研究

Experiments of shed film for crops on farmland show that: the light conversion agricultural films can shorten the growth cycle of crops, increase yield of crops, improve quality of crops. However, the existing light conversion agents have such drawbacks as single light conversion, poor stability, unsuitable fluorescence matching with crops absorption spectrum. In 2001, a novel phenomenon of aggregation-induced emission (AIE) was first found by Tang et al. To gain the novel and efficient light conversion materials used for agricultural films, the project, according to the design principle of AIE compounds and absorption spectra of main pigment in crops, designs and synthesizes new AIE compounds, then evaluates their light stability, and studies their properties and action mechanisms. Firstly, the light stability of common AIE compounds with purple-blue emission are studied in aggregation state, and the key intrinsic factors, such as electron-donor or electron-withdrawing substituents, steric hindrance and molecular skeleton and so on, are explored, which will provide theoretical guidance and experimental support for research of deep color AIE light conversion agents. Secondly, aromatic ketones and perylene diimide derivatives are designed and synthesized, their optics, electrochemistry, compatibility, thermal stability and molecular orbital energy are studied, structure-optical property relationships of two kinds of light conversion agents are established, and dual-band light conversion of sunlight are achieved. Finally, the action mechanisms of light conversion agents are found by studying adding proportion, micromorphology, dispersion state of light conversion agents in resins, optical and mechanical performance of the light conversion film.

农田扣棚实验表明：转光农膜能够缩短作物生长周期，提高作物产量，改善作物品质。但现有转光剂转光单一、稳定性差、光谱匹配性不好。2001年唐本忠等首先发现了聚集诱导发光现象。本项目拟结合AIE化合物的设计原理和作物中主要色素的吸收光谱，通过分子设计与合成、光稳定性评价、转光性能与作用机制研究得到新型高效的农膜用AIE转光材料。本项目通过对常见蓝紫光AIE化合物聚集态下的光稳定性能研究，探索亲电子/吸电子取代基、空间位阻和分子骨架等影响AIE化合物光稳定性的关键内在因素，为深色AIE转光剂的研究提供实验指导和理论支持；通过芳酮和苝酰二亚胺类衍生物的设计、合成与光学、电化学、相容性、热稳定性能和分子轨道能级等方面的研究，建立两类转光剂的构效关系，实现太阳光的双波段转换；通过转光剂在树脂中的添加比例，微观形貌、分散状态及其制备薄膜的光学和力学性能研究，建立转光剂的作用机制。

转光农膜可以缩短作物生长周期，提高作物产量，改善作物品质。为了获得高效的农膜用光转换材料，基于聚集诱导发光原理和热延迟效应，首先我们制备了三种含有四苯乙烯、丙烯腈和二芳基酮骨架的光转换剂。通过对掺杂薄膜的紫外转化率、光稳定性、在高分子基质中的分散性和力学性能研究，三苯基丙烯腈（TPA）具有优异的光稳定性和紫外光转化性能，掺杂薄膜增强的力学性能。接着，为了进一步提高了光转换效率，我们设计合成了六个三芳基丙烯腈和一个二芳基丙烯腈衍生物。其中，Ph4TPA在固态和掺杂膜中的PLQYs分别高达0.833和0.107，几乎是相应状态下TPA的4倍和5倍。此外，在模拟温室环境下，掺杂膜的荧光发射强度在100min内呈现出微小的变化。光热稳定性试验表明，与非晶态相比，结晶状态可以提高染料的光稳定性，环氧化反应是这类荧光材料发射强度降低的主要原因，但通过占据活性位点可以有效的抑制。最后，以湾位取代苝酰亚胺（PDI）染料为核心，成功制备了一系列黄绿光转换剂。PDI荧光色团存在聚集诱导荧光猝灭问题，但在PVC掺杂薄膜中表现出增强的荧光发射特性。特别是PTCDA、t-BuOPTCDA和m-MeOPTCDA的荧光量子产率分别达到0.88、0.84和0.78。同时，m-MeOPTCDA具有显著的光稳定性，通过增强太阳光辐射（129mw/cm~2）160min，掺杂膜的荧光发射强度略有变化，在室外曝晒两个月后，荧光发射强度在9%范围内波动。从光学特性、力学性能和热稳定性等方面对掺杂膜进行了综合评价，m-MeOPTCDA是PDI发光材料中最佳的光转换剂。基于含m-MeOPTCDA和TPA的双层共挤膜的光学特性研究，双层共挤膜可成功实现紫外激发下的蓝紫和红橙光双波段发射，同时黄绿光激发可检测到红橙光单波段发射，通过调节mMeOPTCDA和TPA的添加比例，将为获得不同作物的专用光转换膜提供了一种有效的途径。