纤维素接枝改性芴-苯和咔唑-苯共聚物及其对硝基芳烃的检测

采用Suzuki偶联反应将合成的芴-苯和咔唑-苯共聚物接枝到经化学改性的纸纤维素上,制备了可用于硝基芳烃检测的传感纸纤维素.荧光猝灭研究显示,由于两种传感纸纤维素具有的大比表面积和孔道结构有利于2,4-二硝基甲苯(DNT)蒸气分子的快速扩散,因此二者比薄膜态具有更高的荧光猝灭效率.荧光猝灭的可逆性研究显示,两种传感纤维素经过四次猝灭-恢复循环后,对DNT气态分子依然具有较高的猝灭效率,表明制备的纸纤维素具有良好的荧光猝灭可逆性和稳定性.     

聚集诱导发光应用研究进展

传统的荧光化合物在聚集态时,会导致荧光猝灭;而聚集诱导发光(AIE)化合物在溶液中单分子状态时呈现弱的荧光,但当形成聚集态时发出强的荧光,这是由于分子内旋转受阻(RIR)和聚集形态的改变所致.综述了2008年以来聚集诱导发光最新应用研究进展,如用以检测离子、气体、有机小分子、爆炸物、蛋白、酶等化学/生物传感器;向传统的聚集引起猝灭化合物引入AIE单元,制备高效固态发光器件等;通过压力、热、溶剂蒸汽等调控聚集态,构建可逆的刺激性多重响应材料;发展与生物体具有良好兼容性的聚集体杂化纳米颗粒(如荧光硅纳米颗粒、聚合物胶束、电解质等),以用于生物体内成像、结构解析及检测等.     

二苯乙烯基蒽聚集诱导发光材料体系的研究进展

具有聚集诱导发光(AIE)性质的有机荧光分子由于其扭曲的分子构型,在聚集态或固态表现出显著增强的荧光发射,避免了传统有机荧光分子的浓度猝灭现象,因而在光电器件、生物传感等领域有着广泛的应用.本文着重介绍了具有AIE性质的二苯乙烯基蒽(DSA)衍生物及其在高效固态发光材料、刺激响应材料、生物成像和生物与化学传感等领域的研究进展.     

1,4-双(4′-N,N-二甲基氨基苯乙烯基)萘的合成及荧光性质

利用Wittig反应合成了一个以萘为π-Center的对称型“D-π-D”有机绿色发光化合物1,4 双(4′-N,N-二甲基氨基苯乙烯基)萘(BDASN),并测试了其在不同环境中的光谱性质.在378nm激发波长的激发下,BDASN显示出很强的荧光发射峰,峰位在521nm(CH₂Cl₂).随着溶剂极性增大,最大发射波长红移且荧光强度降低,与“D-π-A”分子具有相似的分子内电荷转移(TICT)行为.在β-环糊精(β-CD)中BDASN的绿色发光带被猝灭,同时在450nm附近蓝发光带的荧光强度骤增.     

染料分子吸附在正、负电性纳米银上的荧光增强及荧光猝灭现象

制备了两种不同表面电性的胶态纳米银,选取阴离子型染料分子荧光素钠、既有阴离子基团又有阳离子的染料分子罗丹明B,研究其在两种纳米银表面的荧光增强及荧光猝灭现象.当罗丹明B(RhB)分子分别吸附在这两种纳米银上时,对负电性纳米银,观察到荧光猝灭、荧光峰红移现象,且在分子的浓度适当时,加入KBr可获得较强的表面增强拉曼光谱;在正电性纳米银上,当分子的浓度较大时观察到荧光猝灭,当分子的浓度较小时观察到荧光增强.而当荧光素钠分子( FS)分别吸附在这两种纳米银上时,在负电性纳米银,观察到荧光猝灭;在正电性纳米银上观察荧光急剧增强现象.从分子的结构及纳米银表面局域场增强或无辐射通道的增加对增强和猝灭的原因作了讨论.     

不同配体的邻菲罗啉铽探针分子及其温敏漆的制备和性能研究

本文以氧化铽(Tb2O3)、甲基丙烯酸(MAA)、水杨酸(HSal)、肉桂酸(HCA)和邻菲罗啉(Phen)为原料,制备了Tb(MAA)_3Phen、Tb(Sal)_3Phen和Tb(CA)_3Phen探针分子,并将探针分子分别加入甲基丙烯酸甲酯(MMA)中,在过氧化苯甲酰(BPO)引发下聚合,制得3种温敏漆样品。采用红外光谱仪、荧光光谱仪和扫描电子显微镜,对探针分子的结构、发光性能、形貌和温敏漆的温度猝灭性能进行了表征,研究了不同配体对探针分子发光性能和温敏漆温度猝灭性能的影响。红外光谱表明成功合成了Tb(MAA)_3Phen、Tb(Sal)_3Phen和Tb(CA)_3Phen探针分子;扫描电镜照片显示Tb(MAA)_3Phen、Tb(Sal)_3Phen和Tb(CA)_3Phen的微观形貌分别为不同三斜棒状和不规则层状;荧光光谱表明Tb(MAA)_3Phen具有最佳的发光性能,相应的温敏漆在25~65℃范围内具有良好的温度猝灭性能和灵敏度。     

聚集诱导发射光笼分子的设计合成及原位光激活成像研究

通过将1,2,4,5-四氮嗪基团引入到聚集诱导发射(AIE)荧光团上,制备了两个光激活的荧光小分子化合物TPA-Tz1和TPA-Tz2.光激活后, TPA-Tz1和TPA-Tz2的荧光强度分别增强了167倍和100倍.光激活的原理是光照导致四氮嗪基团转化为氰基,从而恢复荧光发射.通过密度泛函理论(DFT)计算,TPA-Tz1的猝灭机理为能量转移至暗态(ETDS). TPA-Tz1的激活产物TPA-CN1具有独特的AIE特点,其聚集态分子间发生的电荷转移是导致聚集态荧光蓝移的主要原因.通过溶剂挥发法获得的TPA-Tz1晶体结构揭示了其内部复杂的堆叠结构,氢键和C—H…π作用代替π-π相互作用是同时维持晶格稳定和AIE特性的重要原因.TPA-Tz1具有良好的生物相容性,其最高的细胞抑制率仅有25.3%.因此, TPA-Tz1在细胞水平和多细胞生物秀丽隐杆线虫体内实现了原位的光激活成像.     

氮氧稳定自由基对染料荧光猝灭的研究

一些顺磁物质能猝灭有机分子的发光,如氧已为人们所熟知。近年来,人们发现氮氧稳定自由基对一些有机分子的激发态有猝灭作用,为了进一步了解这种自由基的猝灭特性,本文以 2,2,6,6-四甲氧基氧化哌啶醇为猝灭剂,对三种染料分子(罗丹明6G,9,10-二苯基蒽,蒽)的荧光猝灭进行了研究。猝灭动     

S/R构型烟碱与胰蛋白酶作用机制的研究

在模拟人体生理条件下,应用稳态荧光光谱和紫外可见吸收光谱手段辅助分子对接技术,重点考察了烟碱(NIC)两种对映体与胰蛋白酶(TYP)相互作用的荧光猝灭机理、构象变化及结合模式。结果表明,S-NIC与TYP碰撞结合形成激态复合物而猝灭TYP的内源性荧光,而R-NIC与TYP结合的猝灭机理为动静态结合的混合猝灭类型。R-NIC对TYP荧光猝灭的能力强于S-NIC,且结合常数(Ka)大于S-NIC,但二者在TYP活性空腔中均只有1个高亲和位点。热力学研究结果表明,S-NIC和R-NIC与TYP结合时活化能差异较大,R-NIC与TYP碰撞结合所需能量更小。同步和三维荧光光谱研究发现,NIC两种对映体均诱导了TYP的微环境和构象发生变化。分子对接结果表明,两种对映体均稳定结合于TYP分子的SER-195附近,且R-NIC与氨基酸残基SER-214形成氢键。     

含三苯胺单元的共轭聚合物的合成、表征及应用

采用 Wittig 方法制得了未封端及封端的线性聚三苯胺-对苯乙烯撑型聚合物(分别简称为:TPA-DOPPV1,TPA-DOPPV2),并对共轭聚合物进行了表征和性能测试.封端后的聚合物溶液和固体膜在紫外光照射下均发出较强的绿光.对这类聚合物在硝基化合物检测方面的应用进行了初步研究,结果表明:封端后的共轭聚合物在邻硝基甲苯(o-NT)荧光检测上的性能明显提高,当o-NT 浓度为 21.5×10-3 mol/L 时,荧光猝灭效果达到了 96%;在2,4-二硝基甲苯(DNT)、对硝基甲苯(P-NT)和对苯醌(p-BQ)蒸汽中放置 10 s 时,其薄膜的荧光猝灭效率分别达到 30%、15.6%和 3.1%.TPA-DOPPV2 的合成操作较为简便,具有一定的检测灵敏性,是一种潜在的硝基类爆炸物荧光检测材料.     

Alternated π‐conjugated polymers based on a 1,2‐diiminocyclohexane chiral unit for nitroaromatics sensing

The detection of 2,4‐dinitrotoluene (DNT) by fluorescence quenching of a new class of polyimines consisting in π‐conjugated segments regularly alternated with chiral C₂ symmetry units has been studied for solutions and thin films. Their photophysical properties and their sensitivity towards DNT detection has been compared to those of a small model molecule incorporating the same π‐conjugated segment. In solution, all the compounds exhibit the same photo‐physical properties and sensitivity towards DNT detection. In contrast, for thin films, better performances are observed in static conditions for this new class of polyimines compared to the small model molecule. It seems that C₂ symmetry units prevent from the stacking of the π‐conjugated segments and provide in addition to high fluorescence signal an improved diffusion of the analyte inside the films. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4141–4149, 2009     

Insight of the photoluminescence of atomically precise bimetallic nanoclusters with free electrons

Noble-metal nanoclusters with emission properties are promising candidtes for cell imaging, biosensing, photo-therapy applications due to their ultra-small size, good photostability, and high biocompatibility. It is of great importance to realize the atomic precision of such metal nanoclusters (NCs) because they allow us to investigate the origin of fluorescence at the atomic level. However, compared to quantum dots (QDs) and organic dyes, noble metal nanoclusters usually suffered from low quantum yield, which significantly limited their applications. Doping with other metal atoms is an effective strategy to enhance the fluorescent properties of metal NCs. Therefore, bimetallic nanoclusters possess enhanced emission properties relative to their monometallic counterparts. Although a couple of reviews have existed for bimetallic nanocluster, few of them concern their emissive properties. In this context, the emissive properties of atomically precise bimetallic nanoclusters are summarized in this minireview. Synergistic effect, state of aggregation, assembly, and isomerism on the fluorescence of bimetallic clusters and structure-photoluminescence property correlations are also discussed.     

Insights into the AIEE of 1,8‐Naphthalimides (NPIs): Inverse Effects of Intermolecular Interactions in Solution and Aggregates

Systematic structural perturbation has been used to fine‐tune and understand the luminescence properties of three new 1,8‐naphthalimides (NPIs) in solution and aggregates. The NPIs show blue emission in the solution state and their fluorescence quantum yields are dependent upon their molecular rigidity. In concentrated solutions of the NPIs, intermolecular interactions were found to quench the fluorescence due to the formation of excimers. In contrast, upon aggregation (in THF / H₂O mixtures), the NPIs show aggregation‐induced emission enhancement (AIEE). The NPIs also show moderately high solid‐state emission quantum yields (ca. 10–12.7 %). The AIEE behaviour of the NPIs depends on their molecular rigidity and the nature of their intermolecular interactions. The NPIs 1 – 3 show different extents of intermolecular (π–π and C?H???O) interactions in their solid‐state crystal structures depending on their substituents. Detailed photophysical, computational and structural investigations suggest that an optimal balance of structural flexibility and intermolecular communication is necessary for achieving AIEE characteristics in these NPIs.     

5,12‐Diacetyl‐5,12‐dihydroquinoxalino[2,3‐b]quinoxalines: Solid‐State Fluorescence,AIE Properties,and Orbital Switching by Substituent Effect

The compound 5,12‐diacetyl‐5,12‐dihydroquinoxalino[2,3‐b]quinoxaline 1 a and its derivatives were prepared, and their solid‐ and solution‐state spectroscopic properties were studied; 1 a shows stronger fluorescence in solution than in the solid state due to aggregation caused by self‐quenching. Phenyl‐ or alkoxy‐substituted derivatives 1 b – d show solid‐state fluorescence with moderate quantum yields of about Φ=0.12–0.15, although the corresponding values are 0.01–0.07 in solution. The spectroscopic properties of alkoxy‐substituted derivatives were hardly changed compared to 1 a and 1 b , although 1 a and 1 b have similar absorption and fluorescence maxima in solution and in the solid state. DFT calculations indicate that orbital switching occurs between HOMO and HOMO‐1 and HOMO‐2 due to orbital interactions with introduced substituents. Crystal structure analysis revealed that the molecules have bent structures around tertiary nitrogen atoms and form a characteristic dimeric structure.     

Synthesis and physical properties of triptycene-based oligo(p-phenyleneethynylene)s

A series of symmetrical and unsymmetrical triptycene-based oligo(op-phenyleneethynylene)s were synthesized by deprotection of the acetone protected terminal alkynes, followed by Sonogashira coupling reactions. The photophysical properties of triptycene-based OPEs both in solution and solid state have been investigated by UV–Vis and fluorescence spectroscopy. Interestingly, the obtained compounds show strong fluorescence with partly high quantum yields in solid state, which suggested that triptycene moieties have not only prevented the intermolecular aggregation but also enforced the coplanarity of OPEs backbone in the solid state.     

Bulk Aggregation Based Fluorescence Turn‐On Sensors for Selective Detection of Progesterone in Aqueous Solution

Steroids are polycyclic compounds that share tetracyclic ring as core scaffold, and selective detection of a steroid is challenging owing to their structural similarities. The discovery of chemosensors that recognize progesterone by alteration of self‐aggregation state is described, and these show significant fluorescence turn‐on. A self‐aggregated 48‐membered dansyl library was screened against a series of metabolites in aqueous buffer and discovered two compounds ( PG‐1 , PG‐2 ) exhibited exceptional selectivity for progesterone. Following studies of aggregation properties of probes using dynamic light scattering and transmission electron microscopy supports progesterone recognition lead to the generation of bulk aggregates that induce fluorescence enhancement. Though many fluorescence sensing mechanisms have been proposed, a sensing mode based on the bulk aggregate formation of fluorophore has never been reported, and this may open a new avenue of chemosensor design.     

Unique Solid‐State Emission Behavior of Aromatic Difluoroboronated β‐Diketones as an Emitter in Organic Light‐Emitting Devices

Aromatic difluoroboronated β‐diketone ( BF₂DK ) derivatives are a widely known class of luminescent organic materials that exhibit high photoluminescent quantum efficiency and unique aggregation‐dependent fluorescence behavior. However, there have been only a few reports on their use in solid‐state electronic devices, such as organic light‐emitting devices (OLEDs). Herein, we investigated the solid‐state properties and OLED performance of a series of π‐extended BF₂DK derivatives that have previously been shown to exhibit intense fluorescence in the solution state. The BF₂DK derivatives formed exciplexes with a carbazole derivative and exhibited thermally activated delayed fluorescence (TADF) behavior to give orange electroluminescence with a peak external quantum efficiency of 10 % that apparently exceeds the theoretical efficiency limit of conventional fluorescent OLEDs (7.5 %), assuming a light out‐coupling factor of 30 %.     

Highlights on the Road towards Highly Emitting Solid‐State Luminophores: Two Classes of Thiazole‐Based Organoboron Fluorophores with the AIEE/AIE Effect

Developing a novel, small‐sized molecular building block that may be capable of emitting light in the solid state is a challenging task and has rarely been reported in the literature. BF₂‐containing dyes seem to be promising candidates towards this aim. Two series of new N^NBF₂ complexes showing aggregation‐induced emission (AIE) and aggregation‐induced emission enhancement (AIEE) were designed and synthesized by means of a new protocol, which improved on the traditional method by employing microwave irradiation. The optical and photophysical properties of the BF₂ complexes were investigated in depth. The synthesized complexes showed fluorescence in both solution and the solid state and, in a mixture of tetrahydrofuran/water, may aggregate into fluorescent nanoparticles. The experimental investigation was supported by quantum mechanical calculations. Their availability, stability, large Stokes shifts, and aggregation capabilities, along with their solid‐state emission capability, render this new class of BF₂ complexes promising AIEE/AIE fluorophores for further applications in the fields of fluorescence imaging and materials science.     

不同代硝基芳基苄醚树枝配体轴向取代硅(Ⅳ)酞菁光物理性质的比较

在二氯硅酞菁轴向位置引入硝基芳基苄醚树枝配体是一种减少酞菁配合物聚集体形成,提高其光动力活性的有效方法。本文采用UV/Vis、稳态和瞬态荧光光谱法比较了1-3代硝基芳基苄醚树枝配体轴向取代硅(Ⅳ)酞菁的光物理性质。研究结果表明,随着轴向树枝配体代数的增加,Q带最大吸收峰强度增大,酞菁核荧光强度增强,荧光量子产率降低,荧光寿命增长。研究结果将为开发轴向取代硅(Ⅳ)酞菁配合物作为新型光敏剂提供重要的理论依据。