带萘酚基的多足胺类化合物与ctDNA的相互作用

本工作合成了一系列带萘酚基的多足胺类化合物,对它们在不同溶剂及不同pH条件下的光物理行为进行了详细研究。通过对萘酚基在不同条件下荧光光谱中存在着不同比例的萘酚基和酚负离子发光,可对化合物分子所处环境的特性作出正确的估计。工作还研究了ctDNA对该类化合物荧光的猝灭问题,提出具有三足多胺结构的该类化合物比其他两种化合物-双足及单足多胺化合物有着更强的与DNA相互作用的能力。而插入于DNA双螺旋结构的萘酚基由于能和DNA碱基对发生相互作用而引起荧光猝灭。实验结果表明：DNA的引入,对化合物的两种发光峰的猝灭有着不同的速度常数。对这一现象的机理进行了详细的讨论。     

具有荧光发射能力有机化合物的光物理和光化学问题研究

有机化合物的结构、构象和环境效应对发光化合物的荧光发射具有重要的影响.本文从化合物激发态的衰变过程出发,侧重于过程的光化学与光物理问题对发光行为和机制进行讨论.如:化合物分子结构的受阻和桥键化对发光的影响;光激发下的光诱导电子和电荷转移及其相互转化;化合物扭曲的分子内电荷转移(TICT);溶剂分子和发光化合物分子间不同的相互作用及对发光的影响;在发光过程中存在着最佳的发光构象等.对于这些问题的研究和掌握,将有利于设计和合成具有高荧光量子产率的发光化合物,更好地解释在研究中出现的种种现象和在实际工作中应用它们.文章还引用了大量发光化合物作为实例,对工作中所得的结果进行了详细讨论.     

取代氧翁盐化合物的分子内电荷转移和光谱行为的研究

合成了一组带不同取代基的2,4,6-三芳基氧翁盐化合物, 对它们在不同溶剂中的光物理行为进行了研究表明: 取代基的性质(推或拉电子)和位置(X轴或Y轴)对化合物的发光有很大影响。本工作还利用荧光去偏振方法研究了氧翁盐化合物分子内的能量转移以及通过加入三氟醋酸使叔胺季铵盐化方法, 为这类化合物提供了在非水溶剂中作为荧光指示剂应用的可能性。     

取代氧翁盐化合物的分子内电荷转移和光谱行为的研究

合成了一组带不同取代基的2,4,6-三芳基氧翁盐化合物, 对它们在不同溶剂中的光物理行为进行了研究表明: 取代基的性质(推或拉电子)和位置(X轴或Y轴)对化合物的发光有很大影响。本工作还利用荧光去偏振方法研究了氧翁盐化合物分子内的能量转移以及通过加入三氟醋酸使叔胺季铵盐化方法, 为这类化合物提供了在非水溶剂中作为荧光指示剂应用的可能性。     

硫杂蒽酮类光敏剂光物理行为的研究

本工作对几种新型硫杂蒽酮化合物的光物理行为进行了研究. 并对它们作为敏化剂与鎓盐类化合物及胺类化合物相组合应用时的光化学问题作了考察. 实验结果表明: 所研究的这些光化学反应具有明确的电子转移性质; 此外, 测得的各种动力学常数对了解该类化合物所组成引发体系的适用范围有较大帮助。     

杂多化合物的酸催化特性及其在有机合成反应中的应用

杂多化合物在各个研究领域中的实际应用日趋广泛。特别是在催化领域内，对杂多化合物催化性能和研究越来越引起人们的关注。本文对在均相和非均相体系中杂多化合物的酸催化的最新研究成果和应用进行了综述，对杂多化合物的酸行为进行了简要的概括，并介绍了作者在这方面的工作。     

双[对-N,N-二甲基氨基苄叉]酮类化合物光谱和光物理行为的研究

本工作研究了几种中心部分被束缚的双[对-N,N-二甲基氨基苄叉]酮类化合物的光物理行为.发现中心五元环的化合物比中心六元环的化合物有着高得多的荧光量子产率,在改变介质粘度、研究粘度对荧光量子产率的影响时发现中心六元环化合物最易受粘度变化的影响,对上述这些有趣的现象进行了扼要的分析和讨论.     

氧-火焰离子化检测器的研制及应用

本文介绍选择测定复杂有机混合物中各含氧化合物的氧-火焰离子化(O-FID)检测器,该仪器是专门对氧响应的O-FID检测器,还报道了在O-FID检测器上对含氧化合物的定量校正工作。     

适宜于光聚合过程应用的荧光探针研究

研究了两种探针化合物在安息香醚引发烯类单体光聚合反应中的应用.发现在光聚合反应中,不同的探针化合物有着不同的光谱响应特征和溶致变色行为,显然,这对探针的灵敏度会带来影响.实验结果表明:探针化合物在光聚合反应中能否应用,其光照稳定性起着关键作用.本工作推荐了一种适宜在烯类单体光聚合反应中应用的探针化合物.     

手征性杂氮钛三环化合物的合成

杂氮钛三环(titatrane)(Ⅰ)是一类具有五配体特殊结构的杂环化合物,由于对其合成工作研究的不多,所以这类化合物的一些性质还鲜为人知。我们对杂氮钛三环的合成方法做了改进,将手性中心引入到这类化合物中,合成了下列结构图中(Ⅱ)所示的具有手性的杂氮钛三环。     

Structural tuning intra- versus inter-molecular proton transfer reaction in the excited state

A series of 2-pyridyl-pyrazole derivatives 1-4 possessing five-membered ring hydrogen bonding configuration are synthesized, the structural flexibility of which is strategically tuned to be in the order of 1 > 2 > 3 > 4. This system then serves as an ideal chemical model to investigate the correlation between excited-state intramolecular proton transfer (ESIPT) reaction and molecular skeleton motion associated with hydrogen bonds. The resulting luminescence data reveal that the rate of ESIPT decreases upon increasing the structural constraint. At sufficiently low concentration where negligible dimerization is observed, ESIPT takes place in 1 and 2 but is prohibited in 3 and 4, for which high geometry constraint is imposed. The results imply that certain structural bending motions associated with hydrogen bonding angle/distance play a key role in ESIPT. This trend is also well supported by the DFT computational approach, in which the barrier associated with ESIPT is in the order of 1 < 2 < 3 < 4. Upon increasing the concentration in cyclohexane, except for 2, the rest of the title compounds undergo ground-state dimerization, from which the double proton transfer takes place in the excited state, resulting in a relatively blue shifted dimeric tautomer emission (cf. the monomer tautomer emission). The lack of dimerization in 2 is rationalized by substantial energy required to adjust the angle of hydrogen bond via twisting the propylene bridge prior to dimerization.     

Excited state intramolecular proton transfer (ESIPT): from principal photophysics to the development of new chromophores and applications in fluorescent molecular probes and luminescent materials

In this perspective we introduce the basic photophysics of the excited-state intramolecular proton transfer (ESIPT) chromophores, then the state-of-the-art development of the ESIPT chromophores and their applications in chemosensors, biological imaging and white-light emitting materials are summarized. Most of the applications of the ESIPT chromophores are based on the photophysics properties, such as design of fluorescent chemosensors by perturbation of the ESIPT process upon interaction with the analytes, their use as biological fluorescent tags to study DNA-protein interaction by probing the variation of the hydration, or design of white-light emitting materials by employing the large Stokes shift of the ESIPT chromophores (to inhibit the F?ster energy transfer of the components). The photophysical mechanism of these applications is discussed. Furthermore, a new research topic concerning the ESIPT chromophores is proposed based on our group's results, that is, to develop organic triplet sensitizers with ESIPT chromophores.     

Understanding the aggregation induced emission enhancement for a compound with excited state intramolecular proton transfer character

A few of excited state intramolecular proton transfer (ESIPT) compounds have been discovered for their aggregation induced emission enhancement (AIEE). To understand the AIEE mechanism, an ESIPT compound BTHPB (N-(4-(benzo[d]thiazol-2-yl)-3-hydroxyphenyl)benzamide) with simple structure was designed and synthesized. BTHPB showed apparent AIEE property and the emission efficiency was observed as high as 0.27 in the aggregates. On the basis of viscochromism experiments and calculations employing the linear coupling model, the restriction of the rotation between the two subunits taken place in ESIPT was considered as the main factor for the AIEE. The micro- and femtosecond transient absorption experiments offered evidence for the considerations. Additionally, we also observed a negative effect of aggregation on the fluorescence emission in the system. So the AIEE of ESIPT compound BTHPB originated from the combination effects of positive and negative factors induced by the aggregation.     

Theoretical explorations about the excited state behaviors for two novel high efficient ESIPT compounds

Structural Chemistry - Two high efficient excited state intramolecular proton transfer (ESIPT) compounds (i.e.,...     

Accessing the long-lived triplet excited states in bodipy-conjugated 2-(2-hydroxyphenyl) benzothiazole/benzoxazoles and applications as organic triplet photosensitizers for photooxidations

Bodipy derivatives containing excited state intramolecular proton transfer (ESIPT) chromophores 2-(2-hydroxyphenyl) benzothiazole and benzoxazole (HBT and HBO) subunits were prepared (7-10). The compounds show red-shifted UV-vis absorption (530-580 nm; ε up to 50000 M(-1) cm(-1)) and emission compared to both HBT/HBO and Bodipy. The new chromophores show small Stokes shift (45 nm) and high fluorescence quantum yields (Φ(F) up to 36%), which are in stark contrast to HBT and HBO (Stokes shift up to 180 nm and Φ(F) as low as 0.6%). On the basis of steady state and time-resolved absorption spectroscopy, as well as DFT/TDDFT calculations, we propose that 7-9 do not undergo ESIPT upon photoexcitation. Interestingly, nanosecond time-resolved transient absorption spectroscopy demonstrated that Bodipy-localized triplet excited states were populated for 7-10 upon photoexcitation; the lifetimes of the triplet excited states (τ(T)) are up to 195 μs. DFT calculations confirm the transient absorptions are due to the triplet state. Different from the previous report, we demonstrated that population of the triplet excited states is not the result of ESIPT. The compounds were used as organic triplet photosensitizers for photooxidation of 1,5-dihydroxylnaphthalene. One of the compounds is more efficient than the conventional [Ir(ppy)(2)(phen)][PF(6)] triplet photosensitizer. Our result will be useful for design of new Bodipy derivatives, ESIPT compounds, and organic triplet photosensitizers, as well as for applications of these compounds in photovoltaics, photocatalysis and luminescent materials, etc.     

Excited-state intramolecular proton transfer in 2-(2'-arylsulfonamidophenyl)benzimidazole derivatives: the effect of donor and acceptor substituents

A series of water-soluble 2-(2'-arylsulfonamidophenyl)benzimidazole derivatives containing electron-donating and accepting groups attached to various positions of the fluorophore pi-system has been synthesized and characterized in aqueous solution at 0.1 M ionic strength. The measured pK(a)'s for deprotonation of the sulfonamide group of monosubstituted derivatives range between 6.75 and 9.33 and follow closely Hammett's free energy relationship. In neutral aqueous buffer, all compounds undergo efficient excited-state intramolecular proton transfer (ESIPT) to yield a strongly Stokes-shifted fluorescence emission from the phototautomer. Upon deprotonation of the sulfonamide nitrogen at high pH, ESIPT is interrupted to yield a new, blue-shifted emission band. The peak absorption and emission energies were strongly influenced by the nature of the substituents and their attachment positions on the fluorophore pi-system. The fluorescence quantum yield of the ESIPT tautomers revealed a significant correlation with the observed Stokes shifts. The study provides valuable information regarding substituent effects on the photophysical properties of this class of ESIPT fluorophores in an aqueous environment and may offer guidelines for designing emission ratiometric pH or metal-cation sensors for biological applications.     

Control over Excited State Intramolecular Proton Transfer and Photoinduced Tautomerization: Influence of the Hydrogen‐Bond Geometry

The influence of H‐bond geometry on the dynamics of excited state intramolecular proton transfer (ESIPT) and photoinduced tautomerization in a series of phenol‐quinoline compounds is investigated. Control over the proton donor–acceptor distance (d_DA) and dihedral angle between the proton donor–acceptor subunits is achieved by introducing methylene backbone straps of increasing lengths to link the phenol and quinoline. We demonstrate that a long d_DA correlates with a higher barrier for ESIPT, while a large dihedral angle opens highly efficient deactivation channels after ESIPT, preventing the formation of the fully relaxed tautomer photoproduct.     

Excited-State Intramolecular Proton Transfer: A Short Introductory Review

In this short review, we attempt to unfold various aspects of excited-state intramolecular proton transfer (ESIPT) from the studies that are available up to date. Since Weller’s discovery of ESIPT in salicylic acid (SA) and its derivative methyl salicylate (MS), numerous studies have emerged on the topic and it has become an attractive field of research because of its manifold applications. Here, we discuss some critical aspects of ESIPT and tautomerization from the mechanistic viewpoint. We address excitation wavelength dependence, anti-Kasha ESIPT, fast and slow ESIPT, reversibility and irreversibility of ESIPT, hydrogen bonding and geometrical factors, excited-state double proton transfer (ESDPT), concerted and stepwise ESDPT.     

How To Reach Intense Luminescence for Compounds Capable of Excited‐State Intramolecular Proton Transfer?

Photoinduced intramolecular direct arylation allows structurally unique compounds containing phenanthro[9′,10′:4,5]imidazo[1,2‐f]phenanthridine and imidazo[1,2‐f]phenanthridine skeletons, which mediate excited‐state intramolecular proton transfer (ESIPT), to be efficiently synthesized. The developed polycyclic aromatics demonstrate that the combination of five‐membered ring structures with a rigid arrangement between a proton donor and a proton acceptor provides a means for attaining large fluorescence quantum yields, exceeding 0.5, even in protic solvents. Steady‐state and time‐resolved UV/Vis spectroscopy reveals that, upon photoexcitation, the prepared protic heteroaromatics undergo ESIPT, converting them efficiently into their excited‐state keto tautomers, which have lifetimes ranging from about 5 to 10 ns. The rigidity of their structures, which suppresses nonradiative decay pathways, is believed to be the underlying reason for the nanosecond lifetimes of these singlet excited states and the observed high fluorescence quantum yields. Hydrogen bonding with protic solvents does not interfere with the excited‐state dynamics and, as a result, there is no difference between the occurrences of ESIPT processes in MeOH versus cyclohexane. Acidic media has a more dramatic effect on suppressing ESIPT by protonating the proton acceptor. As a result, in the presence of an acid, a larger proportion of the fluorescence of ESIPT‐capable compounds originates from their enol excited states.     

2-(2-巯苯基)苯并噁唑分子内质子转移取代基电子效应的密度泛函理论研究

在B3LYP/6-31G(d,p)和TDB3LYP/6-31++G(d,p)//CIS/6-31G(d,p)水平上研究了2-(2-巯苯基)苯并噁唑及其衍生物基态和激发态分子内质子转移现象,并探讨取代基电子效应对分子内质子转移的影响,研究结果表明,在基态时,硫醇式异构体为优势构象,供电子取代基使基态分子内正向质子转移能垒(烯醇式→酮式)升高;而吸电子取代基则可降低能垒,有利于基态分子内质子转移并有助于硫酮式异构体的稳定.在激发态时,硫酮式结构为优势构象,所研究的2-(2-巯苯基)苯并噁唑化合物及衍生物均可以发生无能垒或低能垒(≤1.5kJ/mol)的激发态分子内质子转移.巯苯基部分是激发态失活的主要活性部分,供电子基团有利于激发态的质子转移,吸电子基团使激发态跃迁困难,不利于激发态的质子转移.