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1、具有溶剂色变性质的有机双态发光材料的设计、合成及应用摘 要自 2001 年唐本忠院士提出聚集诱导发光(Aggregation-Induced Emission, AIE)的概念以来,对 AIE 的研究引起了人们的广泛关注。传统的有机发光分子通常表现为依赖性发光,他们只有在溶液分散状态下才会具有明亮的荧光发射,而在聚集态时由于 - 堆积使得激发态电子通过非辐射通道驰豫回到基态,从而表现出固体状态下的荧光猝灭现象,也就是解聚诱导发光( DIE),但是这种在固态下不发光的现象极大地限制了其广泛应用。AIE 分子能够在固态或聚集状态下发出明亮荧光而溶液不发光的特点克服了传统 DIE 染料的缺点。但是,
2、无论 DIE分子还是 AIE 分子都只能在单一状态(溶液或固态)下显示明亮的荧光。近些年来人们对有机双态发光材料(DSEgens)越来越感兴趣,因为它们在溶液和固态中都表现出强烈的荧光发射,然而,具有 DSE 特性的有机分子很少,对于其设计规则、结构与性质之间的关系仍然不清晰,实际应用更是少之又少。在本文中,我们通过供体和受体的改变合成了一类新的有机双态发光材料(DSEgens)。首先,提出了双态发光分子的一般设计规则:向扭曲结构的三苯胺骨架中引入不同的吸电子基团,通过供体、受体部分共享模式,设计具有溶剂色变性质并可用于加密防伪的双态发光三苯胺衍生物。另外,在以上规则的基础上分别向二甲氨基、四
3、苯乙烯、三苯胺及咔唑等不同的供体分子中引入丙二腈作为受体,通过分子偶极矩的改变实现发光分子从聚集诱导发光(AIE)到双态发光(DSE)再到分子转子(TICT)的调控。以下是本文的主要研究内容:(1)以三苯胺为母体通过傅克酰基化反应合成了 4-(N,N-二苯胺基)苯甲醛(DPAB),4-(N,N-二苯氨基)(苯基)乙酮(DPPE)和 4-(N,N-二苯氨基)苯基(苯基)甲酮(DPPM)三种双态发光分子。所设计的发光分子在固体和溶液状态下都具有明亮的荧光发射,并表现出依赖于溶剂极性的独特的溶剂色变行为。通过理论计算和实验数据结合提出了具有双态发光(DSE)和溶剂色变特性I的荧光分子的一般设计规则。
4、扭曲分子内电荷转移( TICT)机制可能是这些双态发光(DSE)分子溶剂变色行为的原因,类似于用于粘度测定的传统 TICT 分子,通过温度变化实验探讨了分子构象与发射波长之间的关系。由于其明显的溶剂色变性质和大的斯托克斯位移,我们将其应用于加密防伪。这项工作通过构建部分共享的供体-受体模式和引入非平面结构,清楚地展示了双态发光分子的一般设计规则,并且为 DSE 分子的溶剂化变色现象提供了合理的解释。(2)通过克脑文格尔反应将丙二腈与不同的供电子基团缩合,所有合成的荧光团均含有二氰基( DCN)结构,这些具有不同发光性质的有机发光材料,有的表现出溶液或固态下均不发光,当外界黏度增大时发出明亮荧光
5、,即经典的TICT 现象(例如,2-(4-(二甲基氨基)亚苄基)丙二腈,DMABM),有的表现为溶液或分散状态下不发光,而聚集或固态下发出明亮荧光,即聚集诱导发光AIE 性质(如 2-(4-(1,2,2-三苯基乙烯基)亚苄基)丙二腈,TPVBM),而有的则表现出溶液、固体均发出明亮荧光的双态发光 DSE 性质(如 2-(4-(二苯氨基)亚苄基)丙二腈,DPABM)和 2-(4-(9H-咔唑-9-基)亚苄基)丙二腈,CBM)。通过密度泛函理论(DFT)计算和自然键轨道(NBO)分析,以判断这些化合物确切的供体部分和受体部分,从而发现是由于供受体之间偶极矩的差异导致了不同的发光性质。温度变化实验再
6、次验证了双态发光分子具有溶剂化变色现象的原因。该项研究工作不仅报道了具有长波长和高量子效率的新型双态发光分子,而且从分子极性角度解释了由不同供体产生不同发光现象的原因,实现了对不同发光性质分子的调控。综上所述,我们设计并合成了一类具有溶剂色变性质的双态发光分子(DSEgens),并进一步应用于加密防伪。首先,将三种吸电子基团分别引入到具有扭曲结构的三苯胺分子中,并将所获得的具有溶剂色变性质的双态发光分子用于加密防伪。另外,以丙二腈部分作为电子受体,通过供电子基团的改变合成具有不同发光性质的有机分子,并从分子极性的角度讨论其不同发光现象的原因。其中,所得到的双态发光分子具有大的斯托克斯位移和高的
7、荧光量子产率。关键词:TICT; 溶剂色变;双态发光;聚集诱导发光;防伪IIDESIGN, SYNTHESIS AND APPLICATION OF ORGANICDUAL-STATE LUMINESCENT MATERIALS WITHSOLVATOCHROMISMABSTRACTSince Tang group proposed the concept of aggregation-induced emission (AIE)in 2001, the research on AIE has attracted widespread attention. Traditional dyemol
8、ecules usually appear to disaggregation-induced emission phenomena. Theyexhibit bright fluorescence in the disoved state, but in the aggregated state, because ofthe - stacking interaction, the excited state of such aggregates often relaxe back tothe ground state via non-radiative channels, resulting
9、 in the emission quenching of theluminophores. The property of aggregation-induced quenching phenomenon oftranditional dyes can also be called disaggregation-induced emission (DIE). Thustheir utilization in the solid state has met great challenges. Instead, AIEgens canovercome the shortcomings of tr
10、aditional DIEgens, because they emit intensefluorescence in solid or the aggregated state. However, both DIEgens and AIEgenscan only exhibit bright fluorescence in a single state (solution or solid state). There isa growing interest in organic dual-state emission emitters (DSEgens), intenselyemittin
11、g in both the solution and solid states. However, only a few examplesdemonstrated DSE behaviours. There is no valid design strategy for designingDSEgens with solvatochromism because of the lack of an investigation into therelationship between structure and DSE property. And there are few practicalap
12、plications of DSEgens.In this paper, we synthesized a new class of organic dual-state emissionluminogens (DSEgens) by changing the donors and acceptors. First, the generalIIIdesign strategy for dual-state emssion molecules were proposed: by combining thepartially shared donor-acceptor pattern and tw
13、isted structures, we introduced differentelectron-withdrawing group and designed three dual-state triphenylamine derivativeswith remarkable solvatochromism properties that can be used for encryption andanti-counterfeiting; in addition, based on the above rules, by introducing malononitrileas an acce
14、ptor into different donors such as dimethylamino, tetraphenylethylene,triphenylamine and carbazole, and altering the molecular dipole moment, we realizedthe change of molecules from aggregation-induced emission (AIE) to molecular rotor(TICT) and dual-state emission (DSE). The following are the main
15、contents in thisthesis:(1) Three electron-withdrawing groups were introduced into a sterictriphenylamine molecule, respectively, by Friedel Crafts acylation reactions. Theobtained products are brightly emissive in both the solution and solid state, withsolvatochromism behavior depending on solvent p
16、olarity. Based on theoreticalanalysis and experimental data, a design strategy for fluorescent molecules withdual-state emission (DSE) and solvatochromism properties is reported. A twistedintramolecular charge transfer (TICT) mechanism may be responsible forsolvatochromism behaviours of these DSEgens,