Vapochromism of Hexaphenylsilole

The photoluminescence (PL) of the thin layer of hexaphenylsilole (HPS) on thin-layer chromatograph (TLC) or quartz plate is investigated. The PL of the HPS layer absorbed on the TLC plate can be turned “off” and “on” continuously and reversibly by solvent exposure and evaporation. On the other hand, the PL of the HPS film coated on the quartz plate becomes stronger with a blue-shift in its emission color after fumigation by solvent vapor. After solvent removal, the film does not return to its original blue-green emission. Analyses by SEM, TEM and XRD indicate that the transformation from amorphous to crystalline state is responsible for the vapor-induced stronger and bluer PL.     

Aggregation-induced Emission of Silole Molecules and Polymers: Fundamental and Applications

Aggregation generally quenches the light emissions of chromophoric molecules. In this review, we demonstrate that 1,1-disubstituted 2,3,4,5-tetraphenyl siloles and 2,5-difunctionalized siloles as well as their polymers exhibit the opposite behaviors. Instead of quenching, aggregation has greatly boosted their photoluminescence quantum yields by up to two orders of magnitude, turning them from faint fluorophores into strong emitters. Such “abnormal” phenomenon of “aggregation-induced emission (AIE)” is attributed to restricted intramolecular rotations of the peripheral phenyl rings against the central silole core, which block the nonradiative channel via the rotational energy relaxation processes and effectively populate the radiative decay of the excitons. Utilizing such a novel effect, siloles and their polymers find an array of applications as: sensors for chemicals, explosives, pH, and biomacromolecules (proteins, DNAs and RNAs), indicators for determining CMC and monitoring layer-by-layer self-assembling, biocompatible fluorogens for cell imaging, visualizing agent for DNA gel electrophoresis, biolabels for immunoassay, stimuli-responsive organic nanomaterials, magnetic fluorescent nanoparticles for potential bio-imaging and -separation, and outstanding materials for efficient OLEDs and PV cells.

Characteristics of Aggregation Induced Emission in 1,1-Dimethyl-2,3,4,5-tetraphenyl and 1,1,2,3,4,5-Hexaphenyl Siloles and Germoles

Photoluminescence (PL) characteristics of 1,1-dimethyl-2,3,4,5-tetraphenylsilole, including its unusual and dramatic aggregation-induced emission (AIE), are described and compared to those of 1,1-dimethyl-2,3,4,5-tetraphenylgermole and 1,1,2,3,4,5-hexaphenylgermole. Although the germoles display more efficient PL emission in solution than their silole analogs when molecularly dissolved, the siloles experience a much greater enhancement of luminescence when aggregated. Silole emission is enhanced by over two orders of magnitude in the aggregated state, while aggregation increases germole emission by approximately 30-fold. Low-temperature NMR measurements and transmission electron microscopy (TEM) observations support the hypothesis that the origin of the AIE effect lies in restricted intramolecular rotations (IMR) of the substituent groups about the bonds connecting them to the core metallole ring. This paper is dedicated to Professor Ian Manners and his scientific accomplishments.     

Luminescent aggregates of a starburst silole-triphenylamine adduct for sensitive explosive detection

A starburst luminogen (THPSTPA) consisting of a triphenylamine core and 1,1,2,3,4,5-hexaphenylsilole peripheries is designed and synthesized. Whereas it is weakly luminescent when molecularly dissolved in good solvent, it becomes highly emissive when aggregated in poor solvent, exhibiting a novel phenomenon of aggregation-induced emission (AIE). THPSTPA is morphologically and thermally stable, showing high glass transition and thermal degradation temperatures at 150 and 303 °C, respectively. The emission of its aggregates can be quenched exponentially by picric acid with a quenching constant up to ∼7.0 × 10⁴ L mol⁻¹, suggesting that it can work as a sensitive chemosensor for explosive detection.     

Metal-Based Aggregation-Induced Emission Theranostic Systems

Efficient theranostic systems can realize better outcomes in disease treatment because of precise diagnosis and the concomitant effective therapy. Aggregation-induced emission luminogens (AIEgens) are a unique type of organic emitters with intriguing photophysical properties in the aggregate state. Among the AIEgens studied for biomedical applications, so far, metal-based AIE systems have shown great potential in theranostics due to the enhanced multimodal bioimaging ability and therapeutic effect. This research field has been growing rapidly, and many rationally designed systems with promising activities to cancer and other diseases have been reported recently. In this review, we summarized the recent progress of metal-based AIE materials in bioimaging and biological theranostics, and deciphered the pertinent design strategies. We hope that this review can offer new insights into the development of this growing field.     

具有聚集诱导发光性质的液晶材料 研究进展

介绍了四苯基乙烯类、二苯基丙烯腈类、二苯基乙炔类、聚集诱导发光分子修饰的苯并菲类以及其他的具有聚集诱导发光性质的液晶材料,重点阐述了它们的聚集诱导发光性质和液晶自组装性质,并说明了各自的构效关系。综合文献报道可知:将发光液晶材料应用在光电器件上能极大地节约成本和减少能耗。最后指出,在合成该类发光液晶材料时,需合理地利用聚集诱导发光基团和液晶基团,且研究重点应集中在此类材料发光机理的研究和应用范围的拓展上。     

Molecular Recognition of Spermine using Aggregation-Induced Emission

In this communication we report the synthesis and characterisation of a novel dianionic compound with aggregation-induced emission properties. This compound was able to recognize spermine via a multivalent electrostatic interaction leading to a restriction of intramolecular rotation enhancing the fluorescence emission. This recognition was investigated in detail using UV-Vis and fluorescence spectroscopy. Furthermore the binding stoichiometry was determined via isothermal titration calorimetry. Besides that the structure of the compound was confirmed by X-ray crystallography. To proof the bivalent binding a singly negatively charged control compound was synthesized showing no specific interaction with the amines screened. Theoretical calculations were performed to get a deeper insight in the molecular structure and the electronic transitions.     

试论污染物排放的总量控制、排污交易与环境评价

从污染的总量控制出发探讨了进行污染物排污权交易的现实性和可行性以及对可行性研究中环境评价的影响。     

Synthesis, light emission, and photo-cross-linking of luminescent polyacetylenes containing acrylic pendant groups

New poly(1-phenyl-1-alkyne)s bearing acrylic pendants (-{(C₆H₅)CC[(CH₂)_mOCOCHCH₂]}_n-; P1(m), m=3, 9) with high molecular weights are synthesized in high yields by WCl₆-Ph₄Sn catalyst. The structures and properties of P1(m) are characterized and evaluated by IR, NMR, TGA, UV, and PL analyses. All the polymers are solution-processable and thermally stable (T_d≥380 °C). Upon photoexcitation, the polymers emit strong blue lights with emission efficiencies (>40%) comparable to that of poly(1-phenyl-1-octyne), an emissive disubstituted polyacetylene. No excimeric absorption and emission are observed in the thin films of the polymers. The acrylic moieties of P1(m) are readily cross-linked by UV irradiation without harming their optical properties, which may enable them to find high-tech applications in photoresist, luminescent patterning, and light-emitting diodes.     

发展煤化工所面临的CO_2排放问题及其对策

对我国的二氧化碳(CO2)排放现状和发展煤化工产业所面临的CO2排放问题进行了分析,对现有的CO2综合治理技术进行了归纳和总结,指出地下储存是解决CO2排放问题较为可行的方案。     

发展煤化工所面临的CO2排放问题及其对策

对我国的二氧化碳(CO2)排放现状和发展煤化工产业所面临的CO2排放问题进行了分析,对现有的CO2综合治理技术进行了归纳和总结,指出地下储存是解决CO2排放问题较为可行的方案.     

Influence of Hydrogen Bonding on Low Critical Micellar Concentration Value and Formation of Giant Vesicle of Triazole-Contained Amphiphile

An amphiphile molecule consisting of triazole moiety has been thoroughly investigated using different approaches in its aqueous condition. The studies have discovered the explicit function of its heteroaromatic ability in molecular self-assembling. From the fluorescence evidence, the triazole-based amphiphile has shown that the aggregation-induced emission behavior is mainly due to the triazolyl. It suggests that the triazole is directly involved in the self-assembling mechanism through an intermolecular interaction. This interaction can be verified by the shifting of proton frequency of the triazole, which is clearly shown by the constant frequency of the proton above the critical micellar concentration (CMC) value. The frequency suggests the establishing hydrogen bond that occurred between the hydrogen and the second nitrogen of the adjacent triazole. These results are consistent with the micellization of the molecule which was determined at a very low CMC value (0.1 mM). The absorbance and optical polarizing microscopy results also support the evidence of the growth of giant vesicles produced from the neutralization of the amphiphile. The formation of stable giant vesicles at neutral pH demonstrates the immediate strong hydrogen bonding connections within the triazoles layer in the bilayer. The discovery reveals that internal hydrogen bonds formed from a heteroaromatic with the appropriate molecular arrangement can promote self-aggregation and enhance overall stability.     

Synthesis, thermal stability, light emission, and fluorescent photopatterning of poly(diphenylacetylene)s carrying naphthalene pendant groups

Naphthalene (Nap)-containing poly(diphenylacetylene)s with different spacer lengths (-{C₆H₅CC[C₆H₄O(CH₂)_mO-Nap]}_n-; P1(m), m = 4, 6, 8) are synthesized. The monomers are prepared by etherifications of 1,m-dibromoalkanes with 1-naphthol and 1-(4-hydroxy)phenyl-2-phenylacetylene and are polymerized by TaCl₅-n-Bu₄Sn and WCl₆-Ph₄Sn catalysts. Whereas the tantalum-based catalyst gives insoluble products in low yields, the tungsten-based catalyst furnishes soluble polymers with high molecular weights (M_w up to 5.0 × 10⁴) in satisfactory yields (up to 62%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, UV, PL, and EL analyses. All the polymers are thermally stable: while the polymers lose 5% of their weights at ∼420 °C under nitrogen, no decreases in molecular weights are found after they have been annealed at 200 °C for 2 h in air. When their THF solutions are photoexcited, the polymers emit strong green lights with high efficiencies (up to 98%). No significant shifts in the photoluminescence spectra are observed when the polymers are cast into thin solid films, suggestive of little involvement of aggregative or excimeric emission. A multilayer EL device with a configuration of ITO/P1(8):PVK/BCP/Alq₃/LiF/Al is constructed, which emits a green light of 520 nm with a maximum external quantum efficiency of 0.16%. The spectral stability is outstanding: no recognizable change is observed in the EL spectrum when the device current is raised. Irradiation of a film of P1(8) through a mask photooxidizes and quenches the emission of the exposed regions, resulting in the formation of two-dimensional luminescent photopatterns.     

Effect of pressure on the crystal structure of ettringite

X-ray diffraction and infrared data have been collected from a sample of ettringite from ambient pressure to 6.4 GPa. The sample was found to reversibly transform to an amorphous phase at 3 GPa. The isothermal bulk modulus of ettringite was found to be 27(7) GPa and the incompressibilities of the lattice parameters were found to be 71(30) GPa along a and 108(36) GPa along c.     

人为源氨排放系数的研究

氨的产生、迁移、清除和净化一直是人们关注和研究的课题,近年来广东省珠江三角洲城市人为源氨的排放情况将不容忽视。通过开展珠江三角洲一城市全面的氨排放源调查研究,建立涉及氨排放的各个源的氨排放清单和计算氨的排放系数,为制定地区空气质量保障方案做充分的准备,具有十分重要的意义。     

节能减排科学谈

做好节能减排工作,企业应当从"科学"入手,重点做好规划、管理和科技进步等几个主要环节的工作,达到节能减排目标。     

Ring Transformations of 4,5- to the Isomeric 3,4-Disubstituted Isothiazolium Salts and their oxidation to 1,1-dioxides

4,5-Disubstituted N-phenyl-isothiazolium salts 1 with active 5-methyl group react under the influence of anilines to form 3,4-disubstituted isothiazolium salts 3 . The influence of donor and acceptor substituents in the 2-phenyl group of 1a–h and in the anilines 2 on the ring transformation were studied. The structure of the new salts was confirmed by X-ray analysis. The 3-hydroperoxy-2,3-dihydro-isothiazole 1,1-dioxides ( 12a,d ) and the isothiazole-3(2H)-one 1,1-dioxides ( 14a,d ) are obtained by oxidation of salts 3 with H₂O₂.     

Poly(naphthylenethiophene)s and poly(naphthylenevinylenephenylenevinylene)s: effect of naphthalene positional isomers on the light emitting properties of their polymers

Poly(naphthylenethiophene)s and poly(naphthylenevinylene-phenylenevinylene)s prepared from 1,5-dibromo-3,7-di-t-butylnaphthalene showed a significant blue shift in their UV-vis and photoluminescence spectra compared to copolymers derived from the 1,4-naphthylene system, both in solution and in thin film. This is correlated to a change in conjugation effect of the two positional isomers of naphthalene in the polymer backbone, where in 1,4-conjugation an aromatic sextet remains intact in one of the naphthalene rings whereas 1,5-conjugation involves the loss of resonance energy in the entire naphthalene unit. The series of poly(naphthylenevinylene-phenylvinylene)s emitted blue-green light with very high fluorescence quantum yields (80-95%) in solution. A fabricated device showed external quantum efficiency estimated at 0.2-0.4%, with a relatively high turn-on voltage at ∼7.0 V.     

发射光谱法测定银和锡的探讨

本法为垂直电极直接燃烧法,在1m光栅摄谱仪上进行摄谱,以交流电弧为光源.为了避免对银的沾污,不用缓冲剂,而采用缓冲液及国家一、二级地质标准样作为标准.不用内标元素,以分析线旁的空白处调零,测量分析线的黑度值进行分析.从实验结果表明本法的检出限,精密度,准确度都能满足1:5万化探扫面的要求.测定范围银为0.048～3.2...