Characterization of room temperature phosphorescence of propranolol and the chiral discrimination between R- and S-isomers

Upon addition of a small amount of bromocyclohexane, propranolol displays room temperature phosphorescence in γ-cyclodextrin solution without deoxygenation. Several factors including the pH, and the concentration of γ-cyclodextrin and bromocyclohexane, which affect the room temperature phosphorescence (RTP) intensity and room temperature phosphorescence lifetime of propranolol are studied in detail. Under optimal conditions, the room temperature phosphorescence lifetimes of propranolol enantiomers are measured. The experimental results show that the associated phosphorescence decay curves can be best fitted to mono-exponential patterns and room temperature phosphorescence lifetimes of R- and S-propranolol are 4.60 ms and 5.74 ms, respectively. The difference of the room temperature phosphorescence lifetimes of R- and S-propranolol is 22.05%. Based on that, chiral discrimination of propranolol enantiomers is carried out successfully by time-resolved phosphorescence.     

Recent advances and future prospects in fluorescence and phosphorescence spectroscopy

Various approaches which manipulate the physical and chemical microenvironment of lumiphors are outlined and examples given of surfactant, microcrystalline and cyclodextrin molecular organization. These methodologies can give improved selectivity, and in some cases, enhanced fluorescence and/or phosphorescence intensities. Complimentary methods of generating luminescence via targeted energy transfer, namely, sensitized room temperature phosphorescence and chemiluminescence, are briefly discussed. The power of non-clasical luminescence techniques to produce more useful analytical results is illustrated for micelle-enhanced/sensitized room temperature phosphorescence, a liquid chromatographic/micelle-stabilized phosphorescence detector, and synchronous wavelength scanning/second derivative/micelle-stabilized phosphorescence. The combination of computer-assisted instrumentation and organized chemical microenvironments to obtain the total luminescence spectral profile should provide attomolar sensitivities, and selectivity without prior separation of mixtures on a more routine basis in the near future.     

Halogenation of a twisted non-polar π-system as a tool to modulate phosphorescence at room temperature

Halogenation of a twisted three-fold symmetric hydrocarbon with F, Cl or Br leads to strong modulation of triplet–triplet annihilation and dual phosphorescence, one thermally activated and the other very persistent and visible by eye, with different relative contributions depending on the halide. The room temperature phosphorescence is highly unusual given the absence of lone-pair-contributing heteroatoms. The interplay between the spin–orbit coupling matrix elements and the spatial configuration of the triplet state induces efficient intersystem crossing and thus room temperature phosphorescence even without relying on heteroatomic electron lone pairs. A ninefold increase of the ISC rate after introduction of three bromine atoms is accompanied by a much higher 34-fold increase of phosphorescence rate.

Twisted π-systems investigation showed a very unusual HAE, influencing independently the ISC and the dual phosphorescence emission, one being very persistent at room temperature and visible by eye in powder.     

Solid‐Phase Room‐Temperature Phosphorescence

Abstract

Solid‐phase phosphorescence (SPP) has become an established approach for the trace analysis of organic compounds. More recently, SPP has been successfully applied to the trace analysis for inorganic species. In this mini review, initially a brief overview of SPP is given. Then the important aspects related to adsorption of the phosphors on the solid phase are discussed. In addition, the basic photophysical aspects of phosphorescence are presented. The physicochemical interactions in SPP, such as the rigidity of the solid phase, effects of oxygen and moisture, heavy‐atom salts, and temperature, are considered. Finally, several recent applications of SPP to both organic and inorganic compounds are discussed.     

室温磷光免疫分析研究的进展

对磷光免疫分析研究现状和发展趋势,作简要的概述,并对开展固体基体室温磷光免疫分析的可能性和优势,及其采用多发光分子微球作标记物的几种技术作了介绍,引用文献36篇。     

Phosphorimetric Determination of Polycyclic Aromatic Hydrocarbons in Clinoptilolite-Filled Fibers at Room Temperature

The phosphorescence of polycyclic aromatic hydrocarbons (PAHs) adsorbed on natural zeolite (clinoptilolite) and clinoptilolite-filled acrylic fibers was studied at room temperature. The optimal conditions were selected for the phosphorescence of PAHs extracted from water and water–dioxane solutions at room temperature using clinoptilolite-filled fibers. The phosphorescence of PAHs in the clinoptilolite-filled fibers at room temperature is characterized by a high quantum yield and long lifetimes of PAH triplet states, as was the case at low temperatures (77 K). The results obtained indicate that the adsorbents used offer promise for the analytical chemistry of PAHs.     

TEMPERATURE DEPENDENCE OF THE PHOSPHORESCENCE LIFETIMES OF HETEROGENEOUS TRYPTOPHAN RESIDUES IN GLOBULAR PROTEINS BETWEEN 293 AND 77 K

Abstract— The phosphorescence of five globular proteins containing tryptophan residues was observed in deoxygenated neutral ethylene glycol-phosphate buffer (1:1 by volume) at 293 and 77 K. Their spectral features at 293 K are closely identical to those at 77 K apart from a lack of tyrosine phosphorescence at 293 K. and are independent of the excitation wavelength between 250 and 310 nm. From the present results. it can be concluded that the buried tryptophan residues are the only phosphorescing centers at room temperature. Their phosphorescence lifetimes were measured as a function of temperature in the range from 77 to 293 K. At room temperature, their phosphorescence lifetimes are between about 1 and 500 ms. On the basis of their temperature dependence, the heterogeneous tryptophan environments are discussed in terms of a temperature-activated nonradiative rate. We suggest that the observation of the phosphorescence characteristics of globular proteins containing tryptophan residues buried in the interior of the protein molecule at room temperature is likely to prove useful in probing the protein structure in solution.     

Phosphorescence sensitization via heavy-atom effects in d10 complexes

Heavy atom-induced phosphorescence of organic chromophores that originates from spin?Corbit coupling (SOC) is always accompanied by fluorescence quenching concomitant with a reduction of the triplet excited state lifetime. However, such changes are typically manifest by fluorescence quenching at room temperature and phosphorescence sensitization at cryogenic temperatures. Herein we overview our efforts over the past decade in which both internal and external heavy-atom effects (HAEs) can trigger room temperature phosphorescence (RTP) with dramatic shortening of the phosphorescence radiative lifetime by several orders of magnitude. Such spectral properties render new classes of phosphorescent materials for potential use in organic light-emitting diodes (OLEDs). The molecular systems described in this paper are organic fluorophores that are ??-complexed or ??-bonded to a multinuclear d¹⁰ transition metal center, the presence of which leads to phosphorescence sensitization because of the significant SOC in such materials.     

12种嘌呤类化合物的滤纸基质室温燐光法研究

较为详细地研究了１２种嘌呤类化合物以滤纸为基质的室温燐光（ＲＴＰ）光谱特性与分子结构的关系，以及重原子效应和酸度效应对ＲＴＰ的影响。     

Crystallization-induced phosphorescence of benzils at room temperature

Efficient room temperature phosphorescence (RTP) is rarely observed in pure organic luminogens. However, we have newly observed that benzil and its derivatives are nonluminescent in solvents and thin layer chromatography (TLC) plates, but become highly phosphorescent in crystal state at room temperature, exhibiting typical crystallization-induced phosphorescence (CIP) characteristics. The CIP phenomenon is ascribed to the restriction of intramolecular rotations in crystals owing to effective intermolecular interactions. Such intermolecular interactions greatly rigidify the molecular conformation and significantly decrease the nonradiative deactivation channels of the triplet excitons, thus giving boosted phosphorescent emission at room temperature.     

Spectroscopy behavior of 6-Mercaptopurine, Azathiopurine, and 8-Azaguanine

A comparative study, luminescence behavior of 6-Mercaptopurine (6-MP), Azathiopurine (BAN), and 8-Azaguanine (8-Azan) have been investigated including the low temperature phosphorescence, the low temperature fluorescence, the room temperature phosphorescence (RTP) and the room temperature fluorescence (RTF). The effect of pH on the luminescence intensity is discussed. Analytical characteristics of RTF and RTP of 6-MP, BAN, and 8-Azan have been studied. The lifetime of phosphorescence and the polarity of RTF and RTP have been examined.     

Recent progress on pure organic room temperature phosphorescence materials based on host-guest interactions

Pure organic room temperature phosphorescence (RTP) has been attracting a lot interest recently. So far, many strategies have succeeded in achieving efficient organic RTP materials by increasing the rate of intersystem crossing (ISC) and suppressing non-radiative transitions. In supramolecular chemistry, the control and regulation of molecular recognition based on the role of the host and guest in supramolecular polymers matrix, has attracted much attention. Recently, researchers have successfully achieved room temperature phosphorescence of pure organic complexes through host-guest interactions. The host molecule specifically includes the phosphorescent guest to reduce non-radiative transitions and enhance room temperature phosphorescence emission. This review aims to describe the developments and achievements of pure organic room temperature phosphorescence systems through the mechanism of host-guest interactions in recent years, and demonstrates the exploration and pursuit of phosphorescent materials of researchers in different fields.     

Recent progress on pure organic room temperature phosphorescence materials based on host-guest interactions

The inclusion of specific organic phosphorescent guest molecules by the host molecules can reduce the nonradiative transitions and engender room temperature phosphorescence emission.     

Cyclic Triimidazole Derivatives: Intriguing Examples of Multiple Emissions and Ultralong Phosphorescence at Room Temperature

The performance of solid luminogens depends on both their inherent electronic properties and their packing status. Intermolecular interactions have been exploited to achieve persistent room‐temperature phosphorescence (RTP) from organic molecules. However, the design of organic materials with bright RTP and the rationalization of the role of interchromophoric electronic coupling remain challenging tasks. Cyclic triimidazole has been shown to be a promising scaffold for such purposes owing to its crystallization‐induced room‐temperature ultralong phosphorescence (RTUP), which has been associated with H‐aggregation. Herein, we report three triimidazole derivatives as significant examples of multifaceted emission. In particular, dual fluorescence, RTUP, and phosphorescence from the molecular and supramolecular units were observed. H‐aggregation is responsible for the red RTUP, and Br substituents favor yellow molecular phosphorescence while halogen‐bonded Br⋅⋅⋅Br tetrameric units are involved in the blue‐green phosphorescence.     

蒽醌衍生物的合成与光谱特性

合成了6个蒽醌衍生物(1a~1 f),其中2,3-二氢-9,10-二羟基-1,4-蒽醌(1d)和2,3,4,9-四氢-9-羟基-1,10-蒽醌(1 e)为新的蒽醌衍生物。1a~1 f的结构经UV,1H NMR,IR及MS确定。初步探讨了1a~1 f的荧光和燐光光谱特性。结果表明,1a~1 f都能发射荧光和室温燐光(RTP),尤其是SS-RTP具有较大的Stokes位移和较长的寿命。     

银纳米粒子的绿色合成及其对荧光素室温磷光的增强效应

以β-环糊精(β-CD)作为稳定剂, 葡萄糖为还原剂, 银氨溶液为前驱体, 实现了绿色化学方法合成银纳米粒子. 利用紫外-可见分光光度法(UV-Vis)、高分辨透射电镜(HRTEM)、红外光谱法(FTIR)对产物进行了表征. 将银纳米粒子引入滤纸表面增强室温磷光(RTP)的研究, 发现银纳米粒子对醋酸铅诱导荧光素(FL)所得的RTP具有明显的增强效应, 并且随着银纳米粒子加入量的增加具有先增强后猝灭的趋势. 对β-CD与银纳米粒子的相互作用机理及银纳米粒子对FL RTP增强效应的作用机理进行了初步讨论.     

Supramolecular assembly confined purely organic room temperature phosphorescence and its biological imaging

Purely organic room temperature phosphorescence, especially in aqueous solution, is attracting increasing attention owing to its large Stokes shift, long lifetime, low preparation cost, low toxicity, good processing performance advantages, and broad application value. This review mainly focuses on macrocyclic (cyclodextrin and cucurbituril) hosts, nanoassembly, and macromolecule (polyether) confinement-driven RTP. As an optical probe, the assembly and the two-stage assembly strategy can realize the confined purely organic RTP and achieve energy transfer and light-harvesting from fluorescence to delayed fluorescence or phosphorescence. This supramolecular assembly is widely applied for luminescent materials, cell imaging, and other fields because it effectively avoids oxygen quenching. In addition, the near-infrared excitation, near-infrared emission, and in situ imaging of purely organic room temperature phosphorescence in assembled confinement materials are also prospected.

Purely organic room temperature phosphorescence, especially in aqueous solution, is attracting increasing attention owing to its large Stokes shift, long lifetime, low preparation cost, low toxicity, good processing performance advantages, and broad application value.     

Some aspects of room-temperature phosphorescence in liquid solutions

Experimental requirements for room-temperature phosphorescence measurements in liquids (RTPL) are discussed. Phosphorescence quantum yields and triplet lifetimes of some brominated naphthalenes and halogenated biphenyls at 77 K in 2-methyltetrahydrofuran and at room temperature in hexane are reported and compared. Surprisingly the naphthalenes show only little loss in quantum yields in going from 77 K to room temperature. Sensitized phosphorescence is discussed as a means of expanding the analytical potential of RTPL. Results with a model system of benzophenone as a donor (analyte) and 1,4-dibromonaphthalene as an acceptor are presented.     

Crystallization-induced phosphorescence of pure organic luminogens

This review summarizes the recent progress of efficient room temperature phosphorescence (RTP) from pure organic luminogens achieved by crystallization-induced phosphorescence (CIP), with focus on the advances in our group. Besides homocrystals, mixed crystals and cocrystals are also discussed. Meanwhile, intriguing RTP emission from the luminogens without conventional chromophores is demonstrated.     

Non-protected fluid room temperature phosphorescence of several naphthalene derivatives

In our previous work, we reported that with TlNO(3) as a heavy atom perturber and Na(2)SO(3) as a deoxygenator, room temperature phosphorescence (RTP) emission of dansyl chloride and its amino acid derivatives can be induced directly from their aqueous solution without a protective medium. Is this kind of fluid luminescence phenomenon unique for the dansyl chloride compounds? The present work has shown that many naphthalene derivatives can also exhibit RTP emission in their aqueous solutions under similar conditions in the absence of a protective medium. Such an RTP emission phenomenon could be denoted as nonprotected fluid room temperature phosphorescence (NP-RTP). In order to further understand this new luminescence phenomenon, the substituent group effects and the favorable chemical structure of compounds for NP-RTP emissions are discussed in detail.