新型四苯乙烯基希夫碱的合成与性质研究

发布时间：2018-05-20 09:00

本文选题：TPE + AIE　；参考：《中国矿业大学》2017年硕士论文

【摘要】：聚集诱导发光(AIE)物质在固态或者聚集状态下,因为扭曲构象、堆积形态等变化导致其荧光发射的波长和强度发生改变,使其在有机发光二极管(OLED)、荧光生物探针等领域具有广阔的应用前景。作为典型聚集诱导发光物质的四苯乙烯(TPE),近些年来引起了人们广泛的关注。本论文以希夫碱为结构中心,利用四苯乙烯与一系列水杨醛衍生物反应,设计合成八种希夫碱,并对它们的光物理光化学性质进行了较为系统的研究。初步探索了相关化合物的结晶诱导发光增强CEE(crystallization enhanced emission),分子内扭曲电荷转移(TICT),压致变色(piezallochromy),激发态分子内质子转移(ESIPT)等机理和应用。具体研究结果如下:1.以四苯乙烯为底物合成四苯乙烯胺(TPE-NH2),以水杨醛为底物合成一系列水杨醛衍生物。四苯乙烯胺分别与水杨醛、5-溴水杨醛、5-氯水杨醛、5-氰基水杨醛通过醛胺缩合反应合成四种希夫碱分子,分别对应为化合物1至化合物4。通过研究目标产物的光学性质发现,在四氢呋喃(THF)中加入不良溶剂水时,随着水组分的增加,混合溶液的荧光逐渐增强,也就是说四种希夫碱均具有聚集诱导发光增强性质。当含水的混合溶液静置一段时间后,发现化合物2,3和4的混合溶液荧光强度相比与静置前,发生了明显的增强,且最大发射波长也发生了蓝移。该系列化合物的聚集态发光现象可归因于聚集体的结晶化。这种变化的时间依赖性与分子结晶速度和结晶化程度相关,也就是说,这些材料不仅具备AIE效应,而且还具备晶体发光增强(CEE)特性。2.通过TPE-NH2与5-硝基水杨醛反应合成希夫碱NSTPE。由于硝基的强吸电子性质,化合物NSTPE具有明显的溶剂效应。从NSTPE的密度泛函理论计算可以发现其具有明显的分子内电荷转移倾向。在聚集诱导的过程中,其荧光变化展现的“开-关-开”现象,呈U型,展现了NSTPE的AIE和分子内扭曲电荷转移性质(TICT)性质。除此之外,当用不同溶剂重结晶时,会得到不同固体颜色及不同的荧光发射波长的NSTPE。通过研磨不同溶剂中重结晶出来的固体,它们会同时变成另外一种颜色,在经过二氯甲烷熏蒸过后,研磨后的固体粉末的颜色又恢复到原来的颜色,即NSTPE具有压致变色的性质。通过测试三种颜色下的固体粉末的荧光发射光谱和XRD光谱进一步证实了压致变色性质的结论。3.通过TPE-NH2与5-甲氧基水杨醛,香草醛,3-乙氧基邻羟基苯醛反应合成了三种希夫碱。发现三个化合物都具有ESIPT性质。当用紫外光刺激它们的固体粉末时,三个化合物均立刻由原本的淡黄色变成红色,在室温下经过20 min-2 h不等的时间又会由红色变回原来的颜色。三种希夫碱分子都有羟基氢,所以在激发状态下较容易发生分子内的质子转移。通过测试三个化合物在不同颜色下的漫反射光谱来验证化合物由醇结构到酮式结构的转变。
[Abstract]:The fluorescence emission wavelength and intensity of AIEs are changed due to the changes of the distorted conformation and stacking morphology in the solid or aggregated state. It has a wide application prospect in the fields of organic light-emitting diode (OLED), fluorescent biological probe and so on. As a typical aggregation-induced luminescent substance, Tetrastyrene (TPE) has attracted much attention in recent years. In this paper, eight Schiff bases were designed and synthesized by the reaction of tetrastyrene with a series of salicylidene derivatives, and their photophysical and photochemical properties were studied systematically. The mechanisms and applications of crystallization induced luminescence enhanced CEE(crystallization enhanced emission, intramolecular twisted charge transfer (TICTT), pressure-induced chromotropic piezoelectric (Piezallochromy), excited intramolecular proton transfer (ESIPT) and so on have been preliminarily explored. The specific research results are as follows: 1. A series of salicylaldehyde derivatives were synthesized from tetrastyrene as substrate and salicylaldehyde as substrate. Four Schiff base molecules were synthesized by condensation of tetrastyreneamine with salicylidene 5-bromosalicylaldehyde and 5-chlorosalicylaldehydes via aldehyde-amine condensation respectively, corresponding to compounds 1 to 4, respectively. By studying the optical properties of the target product, it is found that the fluorescence of the mixed solution increases with the increase of the water component when the unfavorable solvent water is added to THF, that is to say, the four Schiff bases have agglomeration induced luminescence enhancement properties. It was found that the fluorescence intensity of the mixed solution of compounds 2C _ 3 and 4 was obviously enhanced and the maximum emission wavelength was blue shift when the mixture solution was stationary for a period of time. The aggregation state luminescence of this series of compounds can be attributed to the crystallization of aggregates. The time dependence of this change is related to the rate of crystallization and the degree of crystallization, that is, these materials not only have AIE effect, but also have the properties of crystal luminescence enhanced CEE. 2. Schiff base NSTPE was synthesized by the reaction of TPE-NH2 with 5-nitrosalicylic aldehyde. Because of the strong electron absorption properties of nitro compounds, compound NSTPE has obvious solvent effect. From the density functional theory (DFT) of NSTPE, it can be found that it has obvious intramolecular charge transfer tendency. In the process of aggregation induction, the fluorescence changes of NSTPE show the "on-open" phenomenon, which shows the AIE of NSTPE and the character of intramolecular twisted charge transfer (TICTs). In addition, when recrystallized in different solvents, NSTPEs with different solid colors and different emission wavelengths can be obtained. By grinding the recrystallized solids in different solvents, they will change into another color at the same time. After fumigation with dichloromethane, the color of the ground solid powder will return to its original color, that is, NSTPE has the properties of pressure-induced discoloration. The results of fluorescence emission spectra and XRD spectra of the solid powders under three colors further confirmed the conclusion of pressure-chromic properties. Three Schiff bases were synthesized by the reaction of TPE-NH2 with 5-methoxy salicylic aldehyde and vanillin 3-ethoxy o-hydroxybenzaldehyde. It was found that all three compounds had ESIPT properties. When the solid powder was stimulated by ultraviolet light, the three compounds immediately changed from light yellow to red, and after 20 min-2 h at room temperature, the three compounds changed from red to original color. All the three Schiff base molecules have hydroxy hydrogen, so the intramolecular proton transfer is easy to occur in the excited state. The diffuse reflectance spectra of three compounds in different colors were tested to verify the transition from alcohol structure to ketone structure.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O621.3

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