近红外ESIPT型有机荧光探针的设计合成及其应用

荧光探针检测因其在活体样品中的高灵敏度、高分辨率和实时检测成像等优势备受关注,广泛应用于化学检测、临床和生物成像等领域。近红外小分子荧光探针具有低背景干扰、高灵敏度和深组织穿透性等优势,不仅能够克服传统荧光探针的局限性,还能在生物成像中展现其特有的优势,因此受到越来越多领域的关注。与传统荧光染料相比,具有激发态分子内质子转移(ESIPT)机制的化合物具有较大的Stokes位移,可以有效消除内滤光作用和荧光自吸收效应,降低自身荧光的干扰,从而提高分子探针检测的灵敏性。此外,这类化合物具有较强的位点可修饰性,可以通过分子对接等方法更好地优化光学性能。因此,本文结合了近红外和ESIPT等优点,设计并合成了一种近红外ESIPT型有机小分子荧光探针,并研究了其在水合肼检测中的可行性。

基于黄酮的ESIPT型荧光探针检测三苯基膦

三苯基膦(PPh3)是一种重要的有机化合物,具有亲核性和还原性,已被广泛用于有机合成和有机金属化合物配位中。然而PPh3的过量使用不可避免地会引起环境的污染,并且对人体的健康也具有潜在威胁。因此我们迫切需要一种方便而高效的检测PPh3的方法。已有检测方法在便捷性和灵敏性等方面不如人意,而小分子荧光探针因其灵敏度高、选择性好、检测简单等优点受到广泛关注。受生物标记领域常用的无痕Staudinger连接反应的启发,本文设计合成了一个类似Staudinger连接反应,以能够具有固态发光性质的激发态分子内质子转移(ESIPT)特性的3-羟基黄酮荧光染料为母核,以邻叠氮苯乙酸酯为识别基团,用于检测PPh3的荧光增强型的探针分子。通过叠氮与PPh3反应,经过氮杂叶立德中间体,进行快速的分子内酰胺化,释放3-羟基黄酮染料并恢复荧光发射,从而实现在溶液中及滤纸上快速检测PPh3的目的。该探针在定量和定性检测PPh3方面具有潜在应用价值。

基于ESIPT机理香豆素荧光化合物的合成和光学性质

以3-碘苯酚为原料,经过甲酰化反应、Knoevenagel缩合反应、Sonogashira偶联和还原反应得到以香豆素为母体的目标化合物7-(甲氧基苯乙炔基)香豆素-3-甲醇(5)。化合物5的结构经过1H NMR,13C NMR和MS(ESI)分析表征确认。并对化合物5的光学性质进行了研究,结果表明:化合物5具有典型的ESIPT发光机理,可以构建比率计量型双光子荧光探针。

基于ESIPT机理的极性敏感荧光探针的理论研究

激发态分子内质子转移(ESIPT)型荧光探针因具有双发射和斯托克斯位移大的特性,近年来受到广泛的关注。实验发现,随着溶剂极性的增大,此类荧光探针M-HA的发射光谱红移且发光强度增强,但这一奇异现象的光物理机制并不清楚。从第一性原理出发,我们研究了M-HA在五种不同极性溶剂中的辐射跃迁和无辐射衰减过程。研究发现,随着溶剂极性的增大,M-HA的吸收和发射波长先红移后趋于不变,激发态表现出杂化的局域-电荷转移(HLCT)特征。烯醇式在无辐射衰减过程中的振动弛豫程度较大,因而发光较弱。酮式的振动弛豫程度随溶剂极性的增大逐渐减小,因而发光逐渐增强。结构弛豫分析表明,酮式的烯基氯及与其相连的部位受溶剂极性影响较大,乙基吲哚部位却影响不大。

含羟基-亚胺基-苯乙烯基-三苯胺有机生色团的合成、表征及ESIPT性质

激发态分子内质子转移（ESIPT）作为自然界和生物体中最重要的基本过程之一，是有机光物理、光生物学与光化学的研究重点。邻羟基-亚胺基片段是能发生ESIPT过程的典型化学片段之一。利用化学结构的可诃性和可控性，设计合成了1个含羟基-亚胺基有机生色团C1，通过熔点、NMR、IR、单晶X—ray检测表征了目标化合物的结构。

A DFT/TD-DFT study of effect of different substituent on ESIPT fluorescence features of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole derivatives

Based on density functional theory(DFT) and time-dependent density functional theory(TD-DFT), the effects of substituent on the excited-state intramolecular proton transfer(ESIPT) process and photophysical properties of 2-(2’-hydroxyphenyl)-4-chloromethylthiazole(HCT) are studied. The electron-donating group(CH_(3), OH) and electronwithdrawing group(CF_(3), CHO) are introduced to analyze the changes of intramolecular H-bond, the frontier molecular orbitals, the absorption/fluorescence spectra, and the energy barrier of ESIPT process. The calculation results indicate that electron-donating group strengthens the intramolecular H-bond in the S_(1) state, and leads to an easier ESIPT process. The electron-withdrawing group weakens the corresponding H-bond and makes ESIPT process a little harder. Different substituents also affect the photophysical properties of HCT. The electron-withdrawing group(CF_(3), CHO) has a little effect on electronic spectra. The electron-donating group(CH_(3), OH) red-shifts both the absorption and fluorescence emission peaks of HCT, respectively, which causes the Stokes shift to increase.

Crystal Structure and ESIPT Phenomena of Anionic 2H-Phenanthro[9,10-c]pyrazol-11-ols

Using 4＇-methoxy-5-hydroxyisoflavone and 4＇,5-dihydroxy-7-methoxyisoflavone as leding compounds,6-methoxy-2 H-phenanthro[9,10-c]pyrazol-11-ol（1 a） and 9-methoxy-2 Hphenanthro [9,10-c]pyrazol-6,11-diol（1 b） were synthesized by two dehydration processes in the EtOH solution.They were characterized by IR,^1H NMR and ^13C NMR.The black prism crystal of 1 a was grown by the slow solvent evaporation technique from 40：1（v/v） CHCl3/MeOH,and it was determined by single-crystal X-ray diffraction.In the crystal structure,1 a was stabilized by intramolecular（O–H···N） and intermolecular（N–H···O,O–H···O,π···π,C–H···π） interactions.In addition,the fluorescence properties of 1 a and 1 b in the base and neutral media revealed that they possessed excited state intramolecular proton transfer phenomena（ESIPT）.

具有ESIPT性质的苯并三氮唑类紫外光稳定剂的研究

苯并三氮唑类衍生物因具有独特的化学结构,其光化学与光物理研究引起人们的关注。笔者介绍了苯并三氮唑类衍生物作为紫外光稳定剂的特点、种类、研究现状以及应用,指出了苯并三氮唑类衍生物的激发态分子内质子转移(ESIPT)的机制,并分析了这类化合物目前研究中存在的问题及以后研究的方向。

一种基于ESIPT原理的反应型半胱氨酸荧光探针的合成及细胞成像研究

本研究基于分子内质子转移机制(ESIPT),制备了一种具有选择性识别Cys的反应型荧光探针(探针1)。在乙腈-磷酸盐缓冲溶液(3:7,体积比,pH 7.4)中,探针1的荧光强度与Cys的浓度在10~100μmol/L范围内呈现良好的线性关系(y=4.127x+42.84,R^(2)=0.9978),检测限为36.7 nmol/L。该探针对Cys的响应具有较大的Stokes位移(160 nm)、高灵敏度和选择性。此外,探针1还具有良好的细胞膜通透性和生物相容性,可用于A549细胞中Cys的荧光成像,在生物分析中具有潜在的应用价值。

一种具有AIE+ESIPT双重属性的席夫碱类荧光探针的合成及在铜离子检测中的应用

设计合成了一种具有聚集诱导发光(AIE)和激发态分子内质子转移(ESIPT)双重属性的席夫碱类荧光探针1。该探针在聚集态下发橙色荧光并表现出较大的斯托克斯(Stokes)位移。实验结果表明,探针1对Cu^(2+)有较高的选择性和灵敏度,检测限为95 nmol/L。Job’s plot曲线分析和质谱结果表明,探针1和Cu^(2+)结合形成1∶1的配合物,阻断了分子原有的ESIPT过程,最终导致荧光淬灭。该探针可用于实际水样中Cu^(2+)的检测。

基于ESIPT机理的近红外硫醇探针及其生物成像研究

本文利用激发态分子内质子转移(ESIPT)过程可产生长波长酮式发射的特点,以HBT(2-(2’-羟基苯基)苯并噻唑)为骨架,2,4-二硝基苯磺酸基作为硫醇位点掩盖酚羟基,与丙二腈缩异佛尔酮通过共轭双键相连,构建了近红外硫醇探针SYN.该探针实现了近红外区对硫醇的定量检测,并在细胞水平上对硫醇进行了成像研究.

一种基于ESIPT传感平台的Al^(3+)荧光探针及其应用

合成了一种基于激发态分子内质子转移(ESIPT)传感平台的高灵敏度性Al^(3+)荧光探针-二氢嘧啶并苯并咪唑衍生物(DPM)。DPM含有邻苯酚羟基,二氢嘧啶和咪唑片段,在HEPES-乙醇缓冲液(3:7,V/V)中能进行ESIPT过程,也可与Al^(3+)螯合。当加入痕量Al^(3+)时,可使DPM由黄绿色荧光(λem=535nm)变为DMP-Al^(3+)螯合物的深蓝色荧光(λem=451nm),荧光强度增强165倍。在其它离子共存下,DMP表现出对Al^(3+)的特异性响应。该探针已用于水样中Al^(3+)的检测,检测限达0.15 nmol/L。此外,DPM能透过细胞膜,可在荧光显微镜下检测细胞内Al^(3+)离子。

基于激发态分子内质子转移(ESIPT)原理的反应型荧光探针研究进展

基于激发态分子内质子转移(ESIPT)原理的反应型荧光探针,因其具有高选择性、高灵敏度及大的斯托克斯位移等优点而被广泛关注.以检测目标物的属性归类,就近十年ESIPT反应型荧光探针进行综述,阐述其检测识别机制,并对此类荧光探针应用中存在的问题及发展方向进行评述.

聚集诱导发光(AIE)和激发态分子内质子转移(ESIPT)结构融合的反应型荧光探针的研究进展

兼具激发态分子内质子转移(ESIPT)和聚集诱导发光(AIE)性质的反应型荧光探针,因其具有较好的生物相容性、良好的传感性能、较大的斯托克斯位移以及较高的荧光量子效率等优点,在近几年来被广泛应用于检测各种阴离子、金属阳离子和生物分子中.简要总结了结构简单,既是AIE结构模块又是ESIPT结构模块的苯并噻唑、水杨醛席夫碱、肼二腙、查尔酮荧光团等反应型荧光探针的研究进展,并对相关研究进行了总结和展望.

激发态分子内质子转移(ESIPT)发色团修饰的树枝形聚合物合成及光物理研究

设计合成了0～4代外围修饰激发态分子内质子转移(ESIPT)发色团的聚酰胺-胺树枝形聚合物G0～G4,化合物结构经过IR,1H NMR,13C NMR和MS表征.稳态光谱研究表明,树枝形聚合物在四氢呋喃溶液中形成了聚集体,发色团酮式发光随着化合物代数增大呈先增加后减小的变化.质子化树枝形聚合物G1-H～G4-H能溶于水,并在水中形成20 nm左右的聚集体,发色团在聚集体疏水区中构象受限,仅发射酮式发光,并且发光强度受树枝形聚合物分子大小的影响.

Electronic effect on the optical properties and sensing ability of AIEgens with ESIPT process based on salicylaldehyde azine

Two novel AIE-active salicylaldehyde azine(SAA) derivatives with a typical excited-state intramolecular proton transfer(ESIPT) process are prepared by introducing electron-withdrawing and donating groups at para-position of phenolic hydroxyl group(CN-SAA and TPA-SAA). The effect of the proton activity in SAA framework on their optical behaviors is investigated spectroscopically. The results from NMR and solvation measurements show that the proton of phenolic hydroxyl group has higher activity when there are electron-withdrawing groups, and the absorption and fluorescence spectra in buffers with different pH also provide the same results. After inviting F. as a nucleophilic probe, this proton activity difference in CN-SAA and TPA-SAA becomes more obvious. The potential application of both molecules is investigated. TPA-SAA exhibits good quantitative sensing ability towards F. with a fluorescence "turn-on" mode, whereas the aggregates of TPA-SAA can selectively and sensitively detect Cu2+ in aqueous solution. From these results, a structure-property relationship is established: the occurrence of ESIPT process will become much easier when linking electron-withdrawing groups at the para-position of phenolic hydroxyl group(e.g., CN-SAA),and it is better to introduce electron-donating groups to enhance the sensing ability towards ions(e.g., TPA-SAA). This work will provide guidance for further design and preparation of AIE-active luminogens with ESIPT process for sensing applications.

Spiropyran isomerization triggering ESIPT for visualization of pH fluctuations during oxidative stress in living cells

Intracellular pH homeostasis is foundation of maintaining normal physiological functions.More and more evidences show that intracellular pH fluctuations were usually associated with many diseases(such as cancer,epilepsy and neurodegenerative diseases).It is very important to develop in situ real-time determination of pH.In recent years,it has been verified that pH can regulate the isomerization process of spiropyran.Thus,we report a pH fluorescent probe BSL,which is a closed loop spiropyran structure by coupling benzothiazole derivatives with indole salts.We utilizes the process of spiropyran isomerization as the trigger of excited state intramolecular proton transfer(ESIPT)effect,and adjust the process of spiropyran isomerization through pH,and then the molecular transformation from enol to ketone(enol:525 nm,ketone:677 nm)through the ESIPT effect.This process achieved accurate measurement of pH.The probe BSL showed sensitive and reversible fluorescence response to pH in vitro.Ultimately,BSL was successfully applied to detect pH fluctuations in cell oxidative stress model.

Four organic crystals displaying distinctively different emission colors based on an ESIPT-active organic molecule

Four crystals A–D based on a structurally simple ESIPT-active molecule 4MPP were obtained by subtly controlling the crystallization conditions. Notably, crystals A and C display single emission bands, which correspond to the keto＊（K＊） and enol＊（E＊） emission, respectively. B and D exhibit dual emission with different proportion of E＊/K＊ emissions while D sucessfully achieves white emssion. The distinctively different emission properties of A–D is mainly because of the change in crystal structures. In addition, A displays amplified spontaneous emission, which indicates its potential as single crystal lasers.

ESIPT-based AIE luminogens:Design strategies,applications,and mechanisms

In this review,we present a systematic and comprehensive summary of the recent development and applications of excited-state intramolecular proton transfer-based(ESIPT-based)aggregation-induced emission luminogens(AIEgens),a type of promising materials that inherit the advantages of ESIPT and AIE,such as large Stokes shift,excellent photostability,and low self-quenching.We first summarize the backbones that have been used to construct the ESIPT-based AIEgens and classify the constructed ones based on the relation between ESIPT and AIE unit.According to the sensing mechanisms and design strategies,we have reviewed the applications of ESIPT-based AIEgens in bioimaging,drug delivery systems,organic lightemitting diodes,photo-patterning,liquid crystal,and the detection of metal cations,anions,small molecules,biothiols,biological enzymes,latent fingerprinting,and so on.We have also reviewed the recent advances in the development of new theoretical methods for investigating molecular photochemistry in crystals and their applications in ESIPT-based AIEgens.We discussed the remaining challenges in this field and the issues that need to be addressed.We anticipate that this review can provide a comprehensive picture of the current condition of research in this field,and promote researchers to make more efforts to develop novel ESIPT-based AIEgens with new applications.

Multiple Hydrogen Bonds Promoted ESIPT and AlE-active Chiral Salic-ylaldehyde Hydrazide

The simpler, the better! A series of simple and highly fluorescent salicylaldehyde hydrazide molecules （41 samples） have been designed and prepared. Even though these soft materials contain a very small π-conjugated system, they can go through multiple intramolecular and intermolecular hydrogen bonds promoted excited-state intramolecular proton-transfer （ESIPT） to display strong blue, green, yellow, and orange aggregation-induced emission （ALE） with large Stokes shifts （up to 184 nm） and high fluorescence quantum yields （φ up to 0.20）. Unusual mechanochromic fluorescence en- hancements are also found in some solid samples. Through coordination, hydrogen and halogen bonds, these flexible molecules can be used as Mg2＋ （φ up to 0.46） probes, universal anion （φ up to 0.14） and unprotected amino acids （φ up to 0.16） probes, and chiral diamine （enantiomeric selectivity and φ up to 0.36 and 0.062, respectively） receptors. Combining their advantages of AlE and biocompatibility, these low cytotoxic dyes have potential application in living cell imaging. Furthermore, the effects of different functional groups on the molecule arrangement, ESIPT, AlE, probe, and chiral recognition properties are also examined, which provide a simple and bright paradigm for the design of multiple-stimuli-responsive smart materials.