有机荧光温度传感体系研究进展

温度是最常见的物理量之一,对温度的精确测量无论在科学研究还是在生产生活中均具有重要意义.荧光温度传感是一种新型半侵入式温度测量方法,具有高灵敏度、快速响应、可视化效果好等优点.有机荧光分子是最早用于荧光温度传感的材料,近年来有机荧光温度传感体系研究取得显著进展.主要对近五年有机荧光温度传感的重要研究成果进行综述,并对其未来发展进行展望.     

Borylated Arylisoquinolines: Photophysical Properties and Switching Behavior of Promising Tunable Fluorophores

A series of nine borylated arylisoquinolines has been prepared with systematic variation in their electronic properties and their photophysical properties were investigated. The color of their fluorescence can be finely tuned by changing the properties of the aryl moiety, which is involved in internal‐charge‐transfer processes. For example, methoxy‐substituted compound 5 showed an intense green emission, whereas dimethylamino‐substituted compound 6 showed an orange‐red emission. These new fluorophores were tested for their potential as molecular switches with external ionic stimuli, such as protons and fluoride ions. On the one hand, protonation of the isoquinoline moiety led to fluorescence enhancement for compounds that showed weak charge transfer and fluorescence quenching for compounds that showed strong charge transfer. On the other hand, the formation of ate complexes with fluoride led to strong fluorescence quenching in all of the investigated cases.     

Logic Information Communication in a Fluorescent Molecular Switch

Based on the chemical‐sensitive fluorescence emission behaviors of the molecular switch 4‐bromo‐5‐methoxy‐2‐(2‐pyridyl)thiazole ( 2‐BMPT ), the communication of logic information between two functional units has been realized. With the rational control of the protonation and coordination reaction of 2‐BMPT , an upstream switching unit (a 1:2 demultiplexer) and two downstream data‐processing units are involved and interconnected in the communication. The two output states of the 1:2 demultiplexer serve as the initial input states of the two parallel downstream data‐processing units, which execute the information communication between the two circuit layers. Furthermore, in the parallel data‐processing layer, the logic gates of INHIBIT and YES accomplish their specific logic functions. Therefore, a molecular cascade circuit composed of an upstream switch and two downstream processing units has been constructed based on the chemical‐modulated fluorescence properties of 2‐BMPT .     

Controlling the Optoelectronic Properties of Pyrene by Regioselective Lewis Base-Directed Electrophilic Aromatic Borylation

Given that pyrene represents one of the most versatile chromophores, the development of new selective routes for its functionalization and tuning of its emission properties is highly desirable. Pyrene-based BN Lewis pair (LP)-functionalized polycyclic aromatic hydrocarbons (PAHs) were prepared by regioselective Lewis base-directed electrophilic aromatic substitution. The requisite 1,6-dipyridylpyrene ligands were accessed by Suzuki–Miyaura cross-coupling of 1,6-bis(pinacolatoboryl)pyrenes with 2-bromopyridine derivatives. Subsequent electrophilic borylation with BCl₃ in the presence of AlCl₃ and 2,6-di-tert-butylpyridine as a hindered base produced the dichloroborane complexes, which were then in situ reacted with diphenyl or diethyl zinc. The presence or absence of alkyl chains in the 3,8-positions of the pyrene moiety determined the position of the B−C bond formation (2,7 in the non-K region versus 5,10 in the K region) and thereby also the size of the BN heterocycle (five- versus six-membered). The impact of the regioisomeric borylation on the electrochemical, photophysical and structural properties was investigated and the conclusions supported by theoretical calculations. The rapid synthesis of derivatives that are borylated in the K region also suggests strong potential for the development of pyrene derivatives that are otherwise difficult to access.     

A Three‐Component Assembly Promoted by Boronic Acids Delivers a Modular Fluorophore Platform (BASHY Dyes)

The modular assembly of boronic acids with Schiff‐base ligands enabled the construction of innovative fluorescent dyes [boronic acid salicylidenehydrazone (BASHY)] with suitable structural and photophysical properties for live cell bioimaging applications. This reaction enabled the straightforward synthesis (yields up to 99 %) of structurally diverse and photostable dyes that exhibit a polarity‐sensitive green‐to‐yellow emission with high quantum yields of up to 0.6 in nonpolar environments. These dyes displayed a high brightness (up to 54 000 m ^?1 cm^?1). The promising structural and fluorescence properties of BASHY dyes fostered the preparation of non‐cytotoxic, stable, and highly fluorescent poly(lactide‐co‐glycolide) nanoparticles that were effectively internalized by dendritic cells. The dyes were also shown to selectively stain lipid droplets in HeLa cells, without inducing any appreciable cytotoxicity or competing plasma membrane labeling; this confirmed their potential as fluorescent stains.     

Syntheses of Some Organic Fluorescent Dyes for Security Tickers

Five organic fluorescence dyes were synthesized by two- or three-step reactions. These synthetic meth-ods have an advantage of the simple processes, low costs and high yields. The compositions of the five compounds are characterized by IR, ^1H NMR, elemental analyses and fluorescence spectroscopies. The quantum yields of fluorescence were measured.     

Modification of Fluorescent Photoinduced Electron Transfer (PET) Sensors/Switches To Produce Molecular Photo‐Ionic Triode Action

The fluorophore‐spacer₁‐receptor₁‐spacer₂‐receptor₂ system (where receptor₂ alone is photoredox‐inactive) shows ionically tunable proton‐induced fluorescence off‐on switching, which is reminiscent of thermionic triode behavior. This also represents a new extension to modular switch systems based on photoinduced electron transfer (PET) towards the emulation of analogue electronic devices.     

基于分子内电荷转移的阴离子比率荧光分子探针

设计合成了一种基于4-甲基-1-羟基二苯甲酮对硝基苯腙的比色和比率荧光阴离子受体1。此类受体以羟基和腙单元为识别位点,以硝基苯基为信号报告基团。向受体1的DMSO溶液中加入AcO-、H2PO4-、F-后,溶液颜色由黄色变为紫红色,而加入所研究的其它阴离子则无变化,从而实现对AcO-、H2PO4-、F-这三种离子的裸眼识别。利用紫外-可见吸收光谱、荧光光谱考察了其与AcO-,H2PO4-,F-,Cl-,Br-,I-等阴离子的识别作用。1H NMR滴定为受体分子与阴离子之间氢键作用本质提供了有力证据。     

A Ratiometric Fluorescent Probe for Hypochlorite Based on a Deoximation Reaction

The first ratiometric fluorescent probe for hypochlorite has been developed through regulation of the electron‐withdrawing ability of the electron acceptor in an intramolecular charge‐transfer (ICT) system by a deoximation reaction (see figure; EWG=electron‐withdrawing group).

     

Photoinduced and Thermal Single-Electron Transfer to Generate Radicals from Frustrated Lewis Pairs

Archetypal phosphine/borane frustrated Lewis pairs (FLPs) are famed for their ability to activate small molecules. The mechanism is generally believed to involve two-electron processes. However, the detection of radical intermediates indicates that single-electron transfer (SET) generating frustrated radical pairs could also play an important role. These highly reactive radical species typically have significantly higher energy than the FLP, which prompted this investigation into their formation. Herein, we provide evidence that the classical phosphine/borane combinations PMes₃/B(C₆F₅)₃ and PtBu₃/B(C₆F₅)₃ both form an electron donor–acceptor (charge-transfer) complex that undergoes visible-light-induced SET to form the corresponding highly reactive radical-ion pairs. Subsequently, we show that by tuning the properties of the Lewis acid/base pair, the energy required for SET can be reduced to become thermally accessible.     

BODIPY类近红外荧光染料的研究进展

近红外BODIPY分子是一类新兴的荧光染料,因其具有优异的光物理和光化学性能而得到广泛的研究,已成为一个新兴的研究热点。本文综述了近年来BODIPY类近红外荧光分子的设计、合成及应用的最新研究进展,并展望了其未来的发展方向和应用前景。     

Fluorescent Molecular Logic Gates and Pourbaix Sensors in Polyacrylamide Hydrogels

Polyacrylamide hydrogels formed by free radical polymerisation were formed by entrapping anthracene and 4-amino-1,8-naphthalimide fluorescent logic gates based on photoinduced electron transfer (PET) and/or internal charge transfer (ICT). The non-covalent immobilisation of the molecules in the hydrogels resulted in semi-solid YES, NOT, and AND logic gates. Two molecular AND gates, examples of Pourbaix sensors, were tested in acidic aqueous methanol with ammonium persulfate, a strong oxidant, and displayed greater fluorescence quantum yields than previously reported. The logic hydrogels were exposed to aqueous solutions with chemical inputs, and the fluorescence output response was viewed under 365 nm UV light. All of the molecular logic gates diffuse out of the hydrogels to some extent when placed in solution, particularly those with secondary basic amines. The study exemplifies an effort of taking molecular logic gates from homogeneous solutions into the realm of solid-solution environments. We demonstrate the use of Pourbaix sensors as pE-pH indicators for monitoring oxidative and acidic conditions, notably for excess ammonium persulfate, a reagent used in the polymerisation of SDS-polyacrylamide gels.     

BODIPY类近红外荧光染料的研究进展

近红外BODIPY分子是一类新兴的荧光染料, 因其具有优异的光物理和光化学性能而得到广泛的研究, 已成为一个新兴的研究热点。本文综述了近年来BODIPY类近红外荧光分子的设计、合成及应用的最新研究进展, 并展望了其未来的发展方向和应用前景。     

方酸菁荧光探针的应用研究进展

功能性方酸菁染料具有独特的D-A-D共轭结构,其在可见光和近红外区域有强烈的吸收和荧光发射。方酸菁染料作为近红外荧光探针母体被应用于蛋白质、氨基酸、一些生物小分子、环境污染物及金属离子等的检测。本文结合课题组近几年工作综述了方酸菁染料在蛋白质、氨基酸、生物小分子、阳离子和其它物质检测方面的应用。     

Near-Infrared Boron Difluoride Formazanate Dyes

Near-infrared (NIR) dyes are sought after for their utility in light harvesting, bioimaging, and light-mediated therapies. Since long-wavelength photoluminescence typically involves extensive π-conjugated systems of double bonds and aromatic rings, it is often assumed that NIR dyes have to be large molecules that require complex syntheses. We challenge this assumption by demonstrating that facile incorporation of tertiary amine groups into readily available 3-cyanoformazans affords efficient production of relatively simple NIR-active BF₂ formazanate dyes (λ_abs=691–760 nm, λ_PL=834–904 nm in toluene). Cyclic voltammetry experiments on these compounds reveal multiple reversible redox waves linked to the interplay between the tertiary amine and BF₂ formazanate moieties. Density-functional calculations indicate that the NIR electronic transitions in BF₂ formazanates are of π→π*-type, but do not always involve strong charge transfer.     

分子内电荷转移双重荧光体识别阴离子研究

设计合成阴离子受体是近年来超分子化学中一个颇为活跃的研究领域[1～ 7] .其中荧光法以其高灵敏度和高选择性等特点使发光受体的设计合成备受关注 [6 ,7] .分子内电荷转移 (Intramolecular charge transfer,ICT)原理已被成功地用于构筑阳离子荧光传感体系[8] ,但将其应用于阴离子识别的研究尚鲜见报道[9～ 12 ] .本文设计合成了 ICT荧光体对二甲氨Scheme 1　 The structures of anion receptors基苯甲酰肼 (DMABH,结构见 Scheme 1 ) ,研究了 DMABH与阴离子如 HSO- 4,Ac O- ,H2 PO- 4,Cl O- 4,NO- 3,Cl- 和 Br- 等结合后的光…     

Charge-transfer emission involving three-coordinate organoboron: V-shape versus U-shape and impact of the spacer on dual emission and fluorescent sensing

New V-shaped bifunctional organosilicon compounds that contain an electron acceptor, B(Mes)2, and an electron donor, N(1-naph)Ph, with the formulae Ph2Si{p-C6H4B(Mes)2}{p-C6H4N(1-naph)ph)} (1), Ph2Si{p-C6H4(Mes)2}{p-biphenyl-N(1-naph)ph} (2), and Si{p-C6H4B(Mes)2}2{p-C6H4N(1-naph)ph)}2 (3) have been synthesized as model compounds for the investigation of through-space charge-transfer emission involving triarylboron and triarylamino centers. The photophysical properties of the new bifunctional organosilicon compounds are compared to two U-shaped compounds sBN and BN in which the boron acceptor and the amino donor groups are linked together by a rigid 1,10-naphthyl group. The results of our investigation establish that dual emission pathways, namely through-space donor-acceptor charge transfer and pi-pi* transitions coexist in the V-shaped molecules 1-3, while charge transfer emission is dominant in the U-shaped molecules. It is found that depending on the geometry of the linker and the BN separation distance, the compound either displays dual emission bands simultaneously or single emission band. In addition, the dual emission pathways in these molecules can be selectively switched on or off by using fluoride ions. The sensitivity of response to fluoride ions by these molecules is also found to be highly dependent on the geometry of the linker and the BN separation distance. The V-shaped molecules are found to be "turn-on" sensors to fluorides with a much higher sensitivity than the U-shaped molecules.     

有机电致发光器件中的双极性蓝光荧光材料

双极性蓝光荧光材料因其双极传输特性和发光特性,为有机电致发光器件性能提升及结构简化提供了新途径。大多数双极性蓝光荧光材料在结构上符合电子给体-π桥-电子受体(D-π-A),根据电子受体单元,本文将其分为二苯磷/磺酰类、二米基硼类、五元杂环类、六元氮杂环类等,讨论了各类材料结构特点及在器件中的应用性能,对非D-π-A型材料也进行了总结。同时,介绍了热活化延迟荧光特性的双极性蓝光荧光材料的进展情况。最后,对双极性蓝光荧光材料中存在的问题进行了提炼,并展望了其发展前景。