非典型发光化合物的簇聚诱导发光

不含大共轭结构的非典型发光化合物因其理论研究的重要性和潜在应用前景引起研究者的广泛关注。非典型发光化合物的结构通常含有N、O、S、P等杂原子,C≡N、C=O、C=C等不饱和单元,及相应的组合功能团(如羟基、胺基、酯基、酐、酰胺、脲基、肟基、砜基等)。近年来,尽管这一领域正快速发展,其发光机理仍存争议。前期,我们提出了簇聚诱导发光(CTE)机理,即含π电子和/或孤对(n)电子的非典型生色团的簇聚及其带来的空间共轭使体系离域扩展,构象刚硬化;同时,其他分子内/间相互作用也有利于簇生色团的刚硬化,从而易于受激发射。基于CTE机理,本文综述了非典型发光化合物的发光特性,包括浓度增强发光、聚集诱导发光(AIE)、激发波长依赖性及磷光发射。CTE机理可合理解释天然产物、合成化合物、生物分子等不同体系的光物理行为,并可用来指导发现和设计新的非典型发光化合物。本文总结了上述不同体系的发展,并对未来研究进行了展望。     

聚己内酯、聚环氧丙烷大单体制备及其与甲基丙烯酸正丁酯共聚合

聚己内酯、聚环氧丙烷大单体制备及其与甲基丙烯酸正丁酯共聚合曹维孝，管治斌，江必旺，冯新德（北京大学化学系北京１００８７１）关键词大单体，聚己内酯，聚环氧丙烷以四苯基卟啉氯化铝（ＴＰＰＡＩ－Ｃｌ）与甲基丙烯酸－β－羟基两酯（ＨＰＭＡ）制备的活性开环催化...     

高对比度多色力致发光变色二苯并富烯衍生物的设计合成及性质研究

制备了苯基甲苯基二苯并富烯（phenyltolyldibenzofulvene,1）并研究了其发光性能.化合物1具有聚集诱导发光（aggregation induced emission,AIE）及结晶诱导荧光增强（crystallization enhanced emission,CEE）的性质,且化合物1可形成蓝色、蓝绿色荧光的晶体以及黄绿色荧光的无定形态.因化合物1分子为扭曲的螺旋桨构象,分子在聚集态中以较疏松的形式堆积,故化合物1可在热、溶剂气氛以及外力刺激下发生多种聚集态间的可逆转变,从而实现在三种不同发光状态间的可逆转变.我们尝试将化合物1用于光学记录,以单一化合物1为发光材料,其可在蓝绿及蓝色荧光颜色背景上以暗黄绿色字迹记录,可通过研磨、加热及溶剂气氛处理擦除字迹,并将记录纸分别转变为蓝色、蓝绿色及黄绿色,因此化合物1有望用于光存储材料.     

聚集诱导发光天然产物:从发现到其多功能应用

来自于天然产物的聚集诱导发光(AIE)材料具有无需化学合成、生物兼容性好、天然可降解、药理活性等优点,正在逐渐成为环境监测、生物成像和疾病诊断等领域的有力工具.本文综述了目前从天然产物中发现的AIE材料,包括黄连素等生物碱、槲皮素等类黄酮多酚、丹宁酸等非类黄酮多酚以及其他皂苷、维生素等天然化合物.这些材料的发光机制主要有分子运动受限(RIM)、扭转分子内电荷转移(TICT)、激发态分子内质子转移(ESIPT)、J-聚集、簇发光(CTE)等.基于显著的AIE特性,这些天然产物表现出在pH、离子及生物标志物传感、细胞成像和生物诊疗等领域的巨大应用潜力.期望本文能够加深对聚集诱导发光现象的理解,启发对来源于天然产物的AIE分子的探索及新应用的开发.     

原子转移自由基聚合制备聚甲基丙烯酸(N-羟基琥珀酰亚胺)酯及其嵌段共聚物

以CuCl/N-苄基-2-吡啶基甲亚胺(NBPM)/2-溴异丁酸乙酯(EBrIB)作为引发催化体系,使甲基丙烯酸(N-羟基琥珀酰亚胺)酯(MASI)进行ATRP聚合,得到的聚甲基丙烯酸(N-羟基琥珀酰亚胺)酯(PMASI)具有较高的单体转化率(90%)、较窄PDI(~1.10)和较高的分子量。在整个聚合过程中,较强的C—Cl键仍使聚合物的端基保持活性,有利于与第二单体甲基丙烯酸(N,N-二甲氨基)乙酯(DMAEMA)嵌段共聚形成结构明确的嵌段共聚物P(MASI-b-DMAEMA)。当MASI的链长较短时,P(DMAEMA40-b-MASI16)具有水溶性并可自组装成直径均匀的核-壳型微胶束,间接证明了聚合过程的可控特征。     

利用邻-碳硼烷可变的C-C键实现发光分子从ACQ到AIE转变

利用邻-碳硼烷骨架中可变的C-C键,将在聚集态会发生猝灭（ACQ）的传统发光分子和具有振动自由度的碳硼烷基团连接起来,合成了带有聚集诱导发光（AIE）效应的邻-碳硼烷基发光分子。通过紫外可见吸收光谱、DFT计算、发射光谱及晶体结构测定等手段,研究了邻-碳硼烷可变的C-C键对化合物性质的影响。结果表明,在邻-碳硼烷骨架的碳原子上引入不同的取代基可以改变C-C键的振动特性,从而能够调控化合物的发光性质,并有效实现从ACQ到AIE的转变。     

一种含苯硼酸基的单体和聚合物的制备及应用

以4-羟基苯硼酸及甲基丙烯酰氯为原料,在三乙胺的存在下,经过酯化反应得到甲基丙烯酸苯硼酸酯。以AIBN为引发剂进行聚合反应,得到聚甲基丙烯酸苯硼酸酯。通过核磁共振氢谱(1HNMR)和傅立叶红外光谱(FTIR)表征了单体和聚合物的结构,利用DSC分析了聚甲基丙烯酸苯硼酸酯的热力学性质。利用聚甲基丙烯酸苯硼酸酯中的硼羟基与多羟基化合物的相互作用,该聚合物可以用来吸附低浓度的聚乙烯醇溶液中的聚乙烯醇。通过COD值测试,证明聚甲基丙烯酸苯硼酸酯可以与低浓度的PVA溶液相互作用,从而降低PVA溶液的COD值。     

固液态均荧光发射的四苯乙烯基衍生物的合成

为了打破传统荧光材料的聚集荧光淬灭(ACQ)的应用限制,通过共价键连接聚集诱导发光(AIE)分子与平面ACQ分子,可以构建在溶液中和固态下都具有荧光发射特性的化合物。分别通过多步反应合成了带有烷基硫醚的萘酰亚胺衍生物3和连接炔吡啶的四苯乙烯衍生物7。化合物3和化合物7通过酰胺缩合,合成了一种四苯乙烯-萘酰亚胺二联体化合物8,化合物8兼具ACQ和AIE分子的特性。结果表明：溶液状态下化合物8具有蓝色荧光发射,其最大发射峰位于452 nm,固态下为黄绿色荧光,最大发射峰位于487 nm。利用三氟乙酸对其荧光进行调控能够实现CIE色坐标为(0.33, 0.32)的单分子白光发射。     

具有聚集诱导发光性质的化合物

具有聚集诱导发光（AIE）性质的有机化合物能够在聚集或固态条件下,通过改变分子组成、扭曲构象、刚性结构、堆积形态等调节荧光发射强度和波长,使其在OLED、化学/生物传感器等领域具有广阔应用前景。本文介绍了到目前有关AIE的研究进展。侧重总结了silole型、取代乙烯型（主要包括亚甲基环戊二烯型和DPDSB型）、腈取代二苯乙烯型、吡喃型、联苯型等小分子化合物和少数高分子的结构与AIE性质之间的关系,以及为解释AIE现象所提出的限制分子内的转动、避免非辐射去活、构象扭曲避免形成excimer、J－聚集态以及形成分子间的C-H/π键等理论。     

具有聚集诱导发光效应的聚炔材料的合成及光学性能研究

合成了三种含有四苯基乙烯结构的双炔烃.这些双炔烃单体通过在CuCl催化下在邻二氯苯中进行的均聚反应可以高产率地生成线型聚炔.所得聚合物均可很好地溶解于常见有机溶剂中,并具有很高的热稳定性.这类聚炔材料在溶液态时几乎不发光,但在聚集态或者固态下可高度发光,表现出典型的聚集诱导发光性质.同时,这些聚合物具有高透光性,可以允许整个可见光区的光透过.其薄膜在400～1700 nm宽波长范围内表现出高折射率（n=1.7787～1.6543）和低色差（D'=0.0003）.紫外光照射可诱使聚合物薄膜发生交联过程,从而调控其折射率数值,并可生成高分辨率的荧光图案.     

Potential For Qualitative Analysis Using Organic Emission Spectra In Flames

Abstract

A preliminary investigation into the potential of using the emission spectra of organic molecules arising from a hydrogen-entrained air flame to obtain structural information has been made. Results for several alcohols show that the technique can be used to distinguish between geometrical isomers.     

White‐Light Emission Strategy of a Single Organic Compound with Aggregation‐Induced Emission and Delayed Fluorescence Properties

A novel white‐light‐emitting organic molecule, which consists of carbazolyl‐ and phenothiazinyl‐substituted benzophenone (OPC) and exhibits aggregation‐induced emission‐delayed fluorescence (AIE‐DF) and mechanofluorochromic properties was synthesized. The CIE color coordinates of OPC were directly measured with a non‐doped powder, which presented white‐emission coordinates (0.33, 0.33) at 244 K to 252 K and (0.35, 0.35) at 298 K. The asymmetric donor–acceptor–donor′ (D‐A‐D′) type of OPC exhibits an accurate inherited relationship from dicarbazolyl‐substituted benzophenone (O2C, D‐A‐D) and diphenothiazinyl‐substituted benzophenone (O2P, D′‐A‐D′). By purposefully selecting the two parent molecules, that is, O2C (blue) and O2P (yellow), the white‐light emission of OPC can be achieved in a single molecule. This finding provides a feasible molecular strategy to design new AIE‐DF white‐light‐emitting organic molecules.     

利用激基复合物发光的有机白光器件制备

以1,4-二(2-氰基-2-苯乙烯基)-2,5-二苯基苯(CNDPDSB)为发光层, N,N'-[3-萘基]-N,N'-二苯基[1,1'-二苯基]-4,4'-二胺(NPB)为空穴传输层, 8-羟基喹啉铝(Alq)为电子传输层, 制备了一种色度稳定的有机电致白光器件. 该器件的白光发射是由CNDPDSB与NPB界面形成的激基复合物发出的红光以及NPB与CNDPDSB发射的蓝光混合而成. 该白光器件的光谱稳定, 在工作电压(6~13 V)内, 色坐标由(0.33, 0.34)变化到(0.31, 0.37). 器件在6 V电压下开启, 10 V电压下的亮度和效率分别为1200 cd/m2和0.2 cd/A.     

Vibrational Quenching in Near-Infrared Emitting Lanthanide Complexes: A Quantitative Experimental Study and Novel Insights

Two series of novel NIR-emissive complexes of Nd³⁺, Sm³⁺, Er³⁺ and Yb³⁺ with two different β-diketonate ligands (L₁=4,4,4-trifluoro-1-phenyl-1,3-butadione and L₂=4,4,4-trifluoro-1-(4-chlorophenyl)-1,3-butadione) are reported. The neutral triphenylphosphine oxide (tppo) ligand was used to replace coordinated water molecules in the first coordination sphere of the as-obtained [Ln(L₁₍₂₎)₃(H₂O)₂] complexes to afford water-free [Ln(L₁₍₂₎)₃(tppo)₂] molecular species. Upon replacement of water molecules by tppo units, the NIR emission lifetimes of the Nd³⁺, Er³⁺and Sm³⁺complexes increase by about one order of magnitude up to values of ≈9, 8 and 113 ms while Yb³⁺ complexes reach intrinsic quantum yields as high as to Φ_Yb=6.5 %., which are remarkably high for fully hydrogenated complexes. Vibrational quenching by CH and OH oscillators has been quantitatively assessed by implementing the Förster's model of resonance energy transfer on the basis of experimental data. This study demonstrates that highly efficient NIR-emitting lanthanide complexes can be obtained with facile, cheap and accessible syntheses through a rational design.     

Photophysical Switching between Aggregation-Induced Phosphorescence and Dual-State Emission by Isomeric Substitution

It is attractive but highly challenging to achieve controllable regulation of photophysical properties of pure organic luminogens, due to distinct work mechanisms and molecular structures. Here, a strategy to regulate in a controllable way the emission behavior of luminogens is reported, according to which long-lived aggregation-induced emission (AIE) can be switched to short-lived dual-state emission (DSE) by an isomer-based substitution reaction. Three luminogens with sharply different photophysical behaviors, including aggregation-induced phosphorescence and dual-state fluorescence emission, were obtained through a substitution reaction with three isomers. Freely rotating structures are attributed to aggregation-induced phosphorescence behavior, whereas twisted rigidification of the molecule greatly contributes to its dual-state emission phenomenon. This work contributes to the controlled regulation of photophysical behaviors through simple reactions and provides a solid evidence to support the key role of the prohibition of intramolecular rotation in aggregation-induced emission process and molecular design of dual-state emitters.     

Transient and Persistent Room‐Temperature Mechanoluminescence from a White‐Light‐Emitting AIEgen with Tricolor Emission Switching Triggered by Light

Persistent luminescence from purely organic materials is basically triggered by light and electricity, which largely confines its practical applications. A purely organic AIEgen exhibits not only persistent photoluminescence, but also transient and persistent room‐temperature mechanoluminescence. By simply turning on and off a UV lamp, tricolor emission switching between blue, white, and yellow was achieved. The data from single‐crystal structure analysis and theoretical calculation suggest that mechanism of the observed persistent mechanoluminescence (pML) is correlated with the strong spin–orbit coupling of the bromine atom, as well as the formation of H‐aggregates and restriction of intramolecular motions in noncentrosymmetric crystal structure. These results outline a fundamental principle for the development of new pML materials, providing an important step forward in expanding the application scope of persistent luminescence.     

Near-Infrared-Emissive AIE Bioconjugates: Recent Advances and Perspectives

Near-infrared (NIR) fluorescence materials have exhibited formidable power in the field of biomedicine, benefiting from their merits of low autofluorescence background, reduced photon scattering, and deeper penetration depth. Fluorophores possessing planar conformation may confront the shortcomings of aggregation-caused quenching effects at the aggregate level. Fortunately, the concept of aggregation-induced emission (AIE) thoroughly reverses this dilemma. AIE bioconjugates referring to the combination of luminogens showing an AIE nature with biomolecules possessing specific functionalities are generated via the covalent conjugation between AIEgens and functional biological species, covering carbohydrates, peptides, proteins, DNA, and so on. This perfect integration breeds unique superiorities containing high brightness, good water solubility, versatile functionalities, and prominent biosafety. In this review, we summarize the recent progresses of NIR-emissive AIE bioconjugates focusing on their design principles and biomedical applications. Furthermore, a brief prospect of the challenges and opportunities of AIE bioconjugates for a wide range of biomedical applications is presented.     

Solid-State Emission and Aggregate Emission of Aroyl- S,N-Ketene Acetals Are Controlled and Tuned by Their Substitution Pattern

Aroyl-S,N-ketene acetals are a novel highly diverse class of aggregation-induced emission fluorogens (AIEgens) with a plethora of interesting properties. An expanded compound library of more than 110 dyes set the stage for the first qualitative control and tuneability of all aspects of their photophysical properties. The interplay of substituents not only allows tuning and prediction of the emission color, but also of the intensity, and quantum yields both in solids and in the aggregated state; these can be rationalized by scrutinizing intermolecular interactions in the crystalline solid state.     

Coordination-Induced Emission from Tetraphenylethylene Units and Their Applications

Thanks to the potential of aggregation-induced emission (AIE) phenomena, improved stabilities, and the good selectivity and sensitivity of the chemical responses exhibited by the products, coordination-driven self-assembly with tetraphenylethylene (TPE) units has recently received much attention and has been widely investigated for application in chemical sensors, cell imaging agents, light-harvesting systems, and others. Several reviews have emerged on the topics of AIE chemistry and aggregation-induced emission luminogen (AIEgen)-based supramolecular assembles, however, there is still a distinct lack of full overviews of emission enhancement from the viewpoint of metal-coordination effects. Thus, this minireview offers recent advances that have been made in the design and application of TPE-based metallacycles, metallacages, metal-organic frameworks (MOFs) and coordination polymers (CPs).