水热法制备非共轭聚集诱导发光聚合物及其在Fe^3+检测中的应用

以“自稳定沉淀聚合”制备的聚马来酸酐-醋酸乙烯酯线性交替共聚物(PMV)为原料,利用水热法制得3种新型非共轭聚集诱导发光(AIE)聚合物.通过荧光光谱、紫外-可见光光谱、傅里叶变换红外光谱(FTIR)、X射线光电子能谱分析(XPS)等表征方法,研究了3种聚合物的荧光和结构特性,并考察了其在Fe3+检测的应用.实验结果表明:3种PMV衍生物均具有AIE性质,随着水热时间的延长,聚合物的发光颜色从蓝色红移至黄色,且水热1 h所得产物固体的绝对量子产率最高,可达17.05%;所得非共轭AIE聚合物可用于Fe3+检测,当Fe3+浓度为5~200μmol/L时,猝灭效率与Fe3+浓度符合线性关系,调整确定系数为0.9922,最低检测限可低至1.22μmol/L.     

Aggregation-induced emission or aggregation-caused quenching? Impact of covalent bridge between tetraphenylethene and naphthalimide

Understanding the physical mechanisms governing aggregation-induced-emission (AIE) and aggregation-caused-quenching plays a vital role in developing functional AIE materials. In this work, tetraphenylethene (TPE, a classical AIEgen) and naphthalimide (NI, a popular fluorophore with ACQ characteristics) were connected through non-conjugated linkages and conjugated linkages. We showed that the nonconjugated-linkage of TPE to NI fragments leads to substantial PET in molecular aggregates and ACQ. In contrast, the conjugated connection between TPE and NI moieties results in the AIE phenomenon by suppressing twisted intramolecular charge transfer. This work provides an important guideline for the rational design of AIE materials.     

Aggregation-induced emission-active antibacterial hydrogel with self-indicating ability for real-time monitoring of drug release process

Although antibacterial hydrogels are emerging as promising biomaterials for effective inhibition of bacterial infections, monitoring their dynamic release behaviors in a visual manner remains greatly challenging. Herein, non-conjugated luminescent polymers (NCLPs) with aggregation-induced emission (AIE) characteristics are used for the first time to develop a visualization strategy to monitor the release process of the drug-loaded hydrogel. The novel antimicrobial peptide polymers with intrinsic AIE effect, namely nanoengineered peptide-grafted hyperbranched polymers (NPGHPs), are encapsulated in an anionic polyelectrolyte to construct the AIE-active fluorescent polymeric hydrogel (NPGHPs/SA gel). Interestingly, the rigid environment mediated by hydrogen bonding and electrostatic interaction contributes to promoting the unconventional luminescence of fluorescent clusters. Moreover, the successive drug release process of NPGHPs/SA gel can be tracked in real time by using fluorescence microscopy. The hydrogel also has potent antibacterial activities against Gram-negative bacteria (E. coli, P. aeruginosa) and Gram-positive bacteria (S. aureus, B. subtilis). Overall, this work not only provides an advanced biomedical material with broad-spectrum antibacterial ability but also opens a facile avenue up for the investigation of drug release from gel systems.     

Fluorogenic Detection and Characterization of Proteins by Aggregation-Induced Emission Methods

Protein is one of the four most important biomacromolecules in living systems. The detection, quantification, localization, and characterization of proteins is essential for an understanding of biological fundamentals, as well as for the diagnostics and treatment of protein-related diseases. By using intrinsic and extrinsic fluorescence, different techniques have been established to study proteins, many of which are now being routinely used in research laboratories and clinics. This review summarizes the applications of aggregation-induced emission (AIE) fluorescence in protein science. In contrast to traditional fluorescent dyes, the activation of AIE dyes is mainly attributed to the restriction of intramolecular motions. This unique turn-on mechanism of AIE dyes allows researchers to develop novel fluorogenic strategies for sensitive, selective, and reliable analysis of proteins. This review focuses on introducing AIE strategies for 1) detection, localization, and quantification of proteins; 2) probing polymer conformational transitions of proteins; 3) characterization of protein–ligand interactions; and 4) evaluation of enzyme activities. Perspectives and challenges with respect to this emerging field of protein characterization are offered.     

Molecular Packing-Controlled Mechanical-Induced Emission Enhancement of Tetraphenylethene-Functionalised Pyrazoline Derivatives

Organic mechanofluorochromic (MFC) materials with mechanical-induced emission enhancement (MIEE) are scarce. Herein, Aggregation-induced emission (AIE)-active tetraphenylethene-functionalised pyrazoline derivatives with various non-conjugated substituent groups (Br, F, N,N-dimethylamino and cyano groups for TPEB, TPEF, TPEN and TPECN, respectively) were designed and synthesised. The fluorescence spectra of the compounds in the solid state were sensitive to mechanical stimuli and exhibited unique MFC properties. The solid fluorescence peaks of all compounds were red shifted, whereas the quantum yields of TPEB, TPEF and TPEN were increased and that of TPECN was slightly reduced after grinding. The MIEE mechanism was systematically investigated through structure–property relationship studies. The results showed that the pyrazoline ring of TPEB with MIEE property formed H-dimer aggregates with weak π–π stacking in the solid state. After grinding, the synergistic effects of conformational planarization and destructive π–π interactions induced the red shift of the fluorescence peak and the intensity enhanced. TPECN formed incompact J-aggregates with weak intermolecular interactions instead. The conformational planarization and increased intermolecular interactions induced by grinding led to the red-shifted peak and the slightly reduced intensity. These results clearly demonstrated that the translation of packing arrangements is an efficient method to design MIEE materials, which opens a new scope for designing unique MFC materials.     

Theoretical study on the aggregation-induced emission mechanism of anthryl-tetraphenylethene

Since the concept of aggregation-induced emission (AIE) was proposed by Benzhong Tang's research group in 2001, the exploration of the mechanism of AIE and the development of new high-performance AIE materials have been the focus and goal of this field. On the basis of a large number of experiment results, AIE mechanism has been well explained by lots of works, such as restricted intramolecular motion (RIM), J-aggregate et al. As tetraphenylethlene (TPE) molecules are stacked, the rotation of the benzene ring rotor is blocked, and the energy attenuation is released in the form of radiation, showing the AIE effect. In order to further explore the AIE effect of TPE, we performed electronic structure, spectrum simulation, and AIE mechanism calculations of the anthryl-tetraphenylethene (TPE-an) monomer and dimer in the gas phase, tetrahydrofuran (THF), and aqueous solutions at the B3LYP/6-31G** level. The calculation results show that TPE-an molecule is in a propeller-like configuration, and its fluorescence intensity is weak; compared with the monomer, the fluorescence intensity of the dimer increases by 87% in aqueous solution; the fluorescence intensity in the gas phase, THF solution, and aqueous solution gradually enhances with the increase of the degree of aggregation, which are consistent with the experimental results. The enhancement of fluorescence intensity is caused by the change of molecular structure caused by aggregation. This detailed AIE luminescence mechanism will provide theoretical guidance for AIE material design.     

利用Reimer-Tiemann反应合成水杨醛缩肼聚集诱导发光分子的综合实验

聚集诱导发光(Aggregation-Induced Emission,AIE)分子是一类在聚集状态下表现出强烈荧光而在分散状态下荧光较弱甚至无荧光的分子。自2001年首例AIE分子被发现以来,各类新型AIE分子如雨后春笋般相继被开发出来,并在有机光电材料、荧光探针、生物成像等领域表现出非常广泛的应用。其中,水杨醛缩肼就是一类合成简单、荧光强度高的典型AIE分子。本论文介绍了利用Reimer-Tiemann反应合成水杨醛,并通过与水合肼反应进一步得到水杨醛缩肼AIE分子的方法。在本实验中,学生不但练习了经典Reimer-Tiemann反应的操作方法,同时也学习了水杨醛缩肼分子的AIE特性及其产生机理。结合拓展阅读,可使学生进一步了解AIE分子的应用。     

聚集诱导发光分子的光电功能与器件应用

光电功能分子通常以薄膜和聚集体的形式显示功能, 聚集诱导发光（AIE）分子体系的发现为解决固态下聚集诱导荧光猝灭（ACQ）难题提供了新的思路. 本文总结了近年来本课题组发展的一系列AIE 分子, 侧重介绍这些AIE 分子的光电功能与器件应用, 特别是在有机电致发光器件和有机激光方面的应用. AIE 材料显示非常高的电致发光效率, 在显示与白光器件方面潜力巨大. 在发展电泵有机激光方面, AIE 材料特点突出, 是最有前景的一类材料.     

A near-infrared fluorescent probe for lipid hydroperoxides in living cells

An NIR (near-infrared) fluorescent probe TCP (tricarbocyanine diphenylphosphine) including a non-conjugated 'pre-tricarbocyanine' was designed and synthesized for visualizing lipid hydroperoxides (ROOH) in living cells. The excitation and emission spectra of tricarbocyanine in the NIR region can effectively avoid background fluorescence interference in biological systems. The probe exhibited a rapid fluorescence response to ROOH and high selectivity for ROOH over other ROS (reactive oxygen species) and some biological compounds, and the limit of detection was 38 pM. In addition, the probe was stable, and less cytotoxic, which indicated that it has potential application in detecting lipid hydroperoxides in living biological systems.     

Fluorogenic Thorium Sensors Based on 2,6‐Pyridinedicarboxylic Acid‐Substituted Tetraphenylethenes with Aggregation‐Induced Emission Characteristics

A novel fluorescent sensor based on tetraphenylethene (TPE) modified with 2,6‐pyridinedicarboxylic acid (PDA) that shows aggregation‐induced emission (AIE) characteristics for thorium recognition with remarkable fluoresence enhancement response has been synthesized. This sensor is capable of visually distinguishing Th⁴⁺ among lanthanides, transition metals, and alkali metals under UV light. Th⁴⁺ can be detected by the naked eye at ppb levels owing to the AIE phenomenon. The sensor showed high selectivity for Th⁴⁺ compared to all other metals tested, and this recognition displayed good anti‐interference qualities. This study represents the first application of a AIE fluorescence sensor in actinide metal recognition and it has potential applications in environmental systems for thorium ion detection.     

Aggregation‐Induced Emission (AIE): A Historical Perspective

Aggregation‐induced emission (AIE) has attracted considerable interest over the last twenty years. In contrast to the large number of available reviews focusing specifically on AIE, this Essay discusses the AIE phenomenon from a broader perspective, with an emphasis on early observations related to AIE made long before the term was coined. Illustrative examples are highlighted from the 20th century where fluorescence enhancement upon rigidification of dyes in viscous or solid environments or J‐aggregate formation was studied. It is shown that these examples already include typical AIE luminogens such as tetraphenylethylene (TPE) as well as stilbenes and oligo‐ or polyphenylenevinylenes and ‐ethynylenes, which became important fluorescent solid‐state materials in OLED research in the 1990s. Further examples include cyanine dyes such as thiazole orange (TO) or its dimers (TOTOs), which have been widely applied as molecular probes in nucleic acid research. The up to 10 000‐fold fluorescence enhancement of such dyes upon intercalation into double‐stranded DNA, attributable to the restricted intramolecular motion (RIM) concept, afforded commercial products for bioimaging and fluorescence sensing applications already in the early 1990s.     

Sub-10 nm Aggregation-Induced Emission Quantum Dots Assembled by Microfluidics for Enhanced Tumor Targeting and Reduced Retention in the Liver

A robust platform is developed to assemble sub-10 nm organic aggregation-induced emission (AIE) particles using four different AIE luminogens (AIEgens) with emissions from green to the second near-infrared window (NIR-II). They are called AIE quantum dots (QDs) to distinguish from typical AIE dots which are larger than 25 nm. Compared with AIE dots that are larger than 25 nm, AIE QDs allow more efficient cellular uptake and imaging without surface modification of any membrane-penetrating peptides or other targeting molecules. NIR-II AIEgens, which have nearly no background fluorescence from organisms, are used to demonstrate that AIE QDs can achieve high contrast at the tumor as small as 80 mm³ and evade the liver more efficiently than AIE dots. AIE QDs hold a good promise for sensitive and precise diagnosis of the latent solid tumor in clinical medicine with much lower off-targeting to the liver than AIE dots.     

Aggregation-Induced Emission: Recent Advances in Materials and Biomedical Applications

The concept of aggregation-induced emission (AIE) has opened new opportunities in many research fields. Motivated by the unique feature of AIE fluorogens (AIEgens), during the past decade, many AIE molecular probes and AIE nanoparticle (NP) probes have been developed for sensing, imaging and theranostic applications with excellent performance outperforming conventional fluorescent probes. This Review summarizes the latest advancement of AIE molecular probes and AIE NP probes and their emerging biomedical applications. Special focus is to reveal how the AIE probes are evolved with the development of new multifunctional AIEgens, and how new strategies have been developed to overcome the limitations of traditional AIE probes for more translational applications via fluorescence imaging, photoacoustic imaging and image-guided photodynamic/photothermal therapy. The outlook discusses the challenges and future opportunities for AIEgens to advance the biomedical field.     

Nucleic acids induced peptide-based AIE nanoparticles for fast cell imaging

Herein, we utilized nucleic acids induced peptide co-assembly strategy to develop novel nucleic acids induced peptide-based AIE (NIP-AIE) nanoparticles. Strong fluorescent of AIE could be observed when a little amount of nucleic acids was added into the peptide solution, and the intensity could be regulated by the concentration of nucleic acids. This AIE nanoparticle with good biocompatibility could achieve fast cell imaging. It is also proved that the fluorescence intensity of AIE decreased with time, which indicates that the reducible cross-linkers of Wpc peptide by GSH and nanoparticles gradually disintegrate in cell. Based on the different of AIE fluorescence signals which regulated by the formation and disintegration of nanoparticles, this AIE system is expected to be used for real-time monitoring of drug release from peptide-based nano carriers in vivo or in vitro, and may provide a new platform for the construction of other organic AIE nanoparticles.     

具有聚集诱导发光性质的近红外荧光染料

聚集诱导发光(AIE)现象的发现为解决传统有机荧光分子在高浓度和聚集形态下存在的荧光猝灭问题提供了最佳方案,并实现了在光电器件、化学传感、生物成像和靶向治疗等众多领域的广泛应用。随着对AIE发光机理研究的不断深入,AIE分子体系得到了极大的扩展。其中,一类具有给体-受体结构的AIE分子能够显著降低分子能隙,使发光分子波长从可见光区(400~700 nm)延伸到近红外(NIR)区(700~1700 nm)。由于NIR发光分子在生物医学领域中的独特优势,其已成为目前AIE研究的热点。随着对NIR分子设计及应用的不断探索,附加不同功能且发光波长更长的AIE分子也被开发出来了,并实现了对生物体特定组织的NIR荧光成像、光声成像、光动力治疗和光热治疗等。本文总结了近年来具有AIE性能的NIR荧光分子的结构及其在生物医学领域的相关应用。     

Enhanced emission efficiency and excited state lifetime due to restricted intramolecular motion in silole aggregates

The aggregation-induced emission (AIE) properties of 1,1,2,3,4,5-hexaphenylsilole (HPS) and poly{11-[(1,2,3,4,5-pentaphenylsilolyl)oxy]-1-phenyl-1-undecyne} (PS9PA) were studied by time-resolved fluorescence technique. The enhanced fluorescence and long fluorescent lifetime were obtained for the sample in an aggregate state as compared to the sample in solution. The time-decay of fluorescence of HPS and PS9PA in high viscosity solvents and low-temperature glasses has also been measured in detail to further investigate the possible mechanism for AIE. Enhanced light emission and long fluorescence lifetime were detected for both HPS and PS9PA in the solution-thickening and -cooling experiments. These results provided direct evidence that the enhanced photoluminescence (PL) efficiency is due to restricted intramolecular motion, which ascribes AIE to the deactivation of nonradiative decay caused by restricted torsional motions of the molecules in the solid state or aggregate form.     

Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non-radiative Decay Pathway

To broaden the application of aggregation-induced emission (AIE) luminogens (AIEgens), the design of novel small-molecular dyes that exhibit high fluorescence quantum yield (Φ_fl) in the solid state is required. Considering that the mechanism of AIE can be rationalized based on steric avoidance of non-radiative decay pathways, a series of bridged stilbenes was designed, and their non-radiative decay pathways were investigated theoretically. Bridged stilbenes with short alkyl chains exhibited a strong fluorescence emission in solution and in the solid state, while bridged stilbenes with long alkyl chains exhibited AIE. Based on this theoretical prediction, we developed the bridged stilbenes BPST[7] and DPB[7], which demonstrate excellent AIE behavior.     

Bridged Stilbenes: AIEgens Designed via a Simple Strategy to Control the Non‐radiative Decay Pathway

To broaden the application of aggregation‐induced emission (AIE) luminogens (AIEgens), the design of novel small‐molecular dyes that exhibit high fluorescence quantum yield (Φ_fl) in the solid state is required. Considering that the mechanism of AIE can be rationalized based on steric avoidance of non‐radiative decay pathways, a series of bridged stilbenes was designed, and their non‐radiative decay pathways were investigated theoretically. Bridged stilbenes with short alkyl chains exhibited a strong fluorescence emission in solution and in the solid state, while bridged stilbenes with long alkyl chains exhibited AIE. Based on this theoretical prediction, we developed the bridged stilbenes BPST[7] and DPB[7], which demonstrate excellent AIE behavior.     

Aggregation-induced emission

Luminogenic materials with aggregation-induced emission (AIE) attributes have attracted much interest since the debut of the AIE concept in 2001. In this critical review, recent progress in the area of AIE research is summarized. Typical examples of AIE systems are discussed, from which their structure-property relationships are derived. Through mechanistic decipherment of the photophysical processes, structural design strategies for generating new AIE luminogens are developed. Technological, especially optoelectronic and biological, applications of the AIE systems are exemplified to illustrate how the novel AIE effect can be utilized for high-tech innovations (183 references).     

聚集诱导发光新材料9,10-双[2-(1-甲基-1H-吡咯-2-基)乙烯基]蒽的 合成及性能

合成并全面表征了一种新的蒽烯类化合物9,10-双[2-(1-甲基-1H-吡咯-2-基)乙烯基]蒽(MPVAn). 该化合物具有显著的聚集诱导发光特性. 它在溶液态时几乎不发光, 但在固态时的光致发光强度达到溶液态的数百倍. 为了确定标题化合物的聚集诱导发光机制, 研究了它在不同溶液粘度及温度下的光致发光行为, 结果表明聚集态发光增强是由于分子内转动受阻所致. 它的粉末在420 nm光的激发下发射纯的黄光, 峰值为562 nm, 半峰宽为66 nm. 采用紫外-可见吸收光谱及循环伏安法研究了化合物的电子性能, 其HOMO和LUMO能级分别为－4.78和－2.28 eV.