压致变色聚集诱导发光材料

聚集诱导发光化合物分子具有特殊的螺旋桨形扭曲构象结构, 导致其很难在结晶状态下进行紧密堆砌, 使得其结晶结构容易在外力的作用发生改变, 致使其分子能级水平和发光光谱发生变化, 产生压致发光变色现象. 因此, 聚集诱导发光化合物是压致发光变色材料的一个重要来源. 压致变色聚集诱导发光材料是一类重要的压致发光变色材料, 其既具有压致发光变色的性能, 又具有聚集诱导发光的性能. 它是一类智能材料, 在应力传感、商标防伪和发光器件等领域具有重要的潜在应用, 近年来受到人们极大的关注. 本文分类介绍了近年来压致变色聚集诱导发光材料的研究进展.     

Photoactivated Fluorescence Enhancement in F,N‐Doped Carbon Dots with Piezochromic Behavior

Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co‐doped carbon dots (F,N‐doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N‐doped CDs increases with UV light irradiation (5 s–30 min), accompanied with a blue‐shift of the fluorescence emission from 586 nm to 550 nm. F,N‐doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N‐doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure‐triggered aggregation‐induced emission in the range 1.0 atm–0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high‐pressure conditions and enhances their anti‐photobleaching.     

超支化聚合物的光物理行为及其压力效应

在溶液中观察到超支化聚合物2-甲氧基-5-（2’-乙基已氧基）-对-苯乙烯/3 ，5-二乙烯基苯共聚体（MEH-PPV-HS_1）具有很强的荧光发射，并且在紫外区有两 个明显的相邻吸收带。分别激发这两个吸收带得到相同的荧光发射。在压力作用下 ，这两个吸收带表现出不同的压力效应，并且在不同的压力下分别激发这两个吸收 带时，所得到的荧光发射效率随压力的变化趋势表现出明显的不同。结果表明，这 两个相邻的吸收带分别来自于超支化聚合物分子中具有不同长短的有效共轭结构。 不同的共轭结构受光激发后到达不同的激发态。然后经过不同的松弛途径到达相同 的发光激发态而发出荧光。     

近红外发光稀土配合物及杂化材料研究进展

稀土因其特殊的物理和化学性质,在信息技术、能源技术、生物技术等高科技领域及国防建设等方面都起着非常重要的作用,中国作为稀土大国,十分重视对稀土材料的研究和开发。稀土离子近红外发光(750～1700 nm)在激光和光纤通讯、医学诊断、免疫分析等热门领域的潜在应用,受到了科研人员的极大关注。稀土离子本身发光极弱,通过分子内传能有机配体可以敏化稀土离子发光,但稀土配合物常受外界干扰,其稳定性较差,若将其与凝胶、介孔材料、离子液体等无机基质复合,得到具有良好光、热稳定性和化学稳定性的有机/无机杂化材料。总结了近些年来近红外发光稀土配合物及近红外发光稀土杂化材料的研究进展,并对其发展前景进行了展望。     

Design and Synthesis of Piezochromic Materials Based on Push–Pull Chromophores: A Mechanistic Perspective

Computational analysis predicts that intramolecular charge transfer (ICT) exists in anthraquinone imide (AQI) derivatives with electron‐donating substituents at the 6‐position, such as 4‐methoxylphenyl, 4‐N,N‐dimethylaminophenyl, and thiophene. However, for those with electron‐withdrawing ones, no clear ICT interaction could be observed. We predicted, on the basis of the simulation results, that AQI derivatives with electron‐donating substituents would be piezochromic. To verify this hypothesis, the corresponding AQI derivatives with various substituents were synthesized. Absorption spectra recorded with a diffuse reflectance method on powders revealed that 4‐methoxylphenyl‐, 4‐N,N‐dimethylaminophenyl‐, and thiophene‐substituted AQI exhibited piezochromism, but not 4‐nitrophenyl‐substituted AQI, which is in good agreement with the simulation results. Interestingly, redshifts of both the lower and higher energy absorption bands were observed along with redshifts of the emission spectra. However, XRD patterns before and after being pressed presented no significant changes, which was different from known piezochromic molecules described in the literature. An unprecedented mechanism in which enhanced ICT from better conjugation between the donor and acceptor segments induced by the decrease of θ under pressure could be responsible for the piezochromism of aryl‐substituted AQIs is proposed.     

Pressure‐Induced Emission Enhancement of a Series of Dicyanovinyl‐Substituted Aromatics: Pressure Tuning of the Molecular Population with Different Conformations

A series of dicyanovinyl‐substituted aromatic compounds (Ar‐DCV; Ar=9‐anthracenyl, 1‐naphthyl, 1‐pyrenyl) with dual fluorescence are prepared, and their emission properties—when molecularly dispersed in a polymer medium—are investigated under pressure perturbation. The total emission intensity is enhanced drastically from ambient pressure up to 70 kbar. Emission 30–107 times more intense than that at ambient pressure is observed at higher pressure. In dual emission, the enhancement of the local excited state (LE state) is significantly different from that of the intramolecular charge‐transfer state (ICT state). The intensity of the ICT emission increases faster (30–370 times) than that of the LE emission (less than 20 times). In accordance with spectroscopic data, emission dynamics at different pressures, and computational studies on the molecular conformations of these compounds, a kinetic model is proposed to explain the effect of pressure on the emissive properties of the Ar‐DCV compounds from the point of view of pressure‐dependent populations of the species in the ground state.     

两种萘酰亚胺类化合物及其聚合物荧光性质的研究

本文以1,8萘酰亚胺为原料,合成了两种萘酰亚胺类型的化合物,系统地研究了它们在不同溶剂中的吸收光谱和荧光光谱.并以这两种化合物单体为基础,通过共聚合成了它们与甲基丙烯酸甲酯和N 乙烯基咔唑的嵌段共聚物.研究了聚合物在溶液和薄膜中的荧光性质.研究结果证明,所得共聚物不但保持了单体的基本荧光特性,其溶解性、成膜性、热稳定性等都得到了大大改善,是一种有应用前景的有机发光半导体材料.此外,本文还利用荧光猝灭的手段研究了萘酰亚胺类化合物与C₆₀之间的相互作用.     

Exploring the Free Energy and Conformational Landscape of tRNA at High Temperature and Pressure

A combined temperature‐ and pressure‐dependent study was employed to reveal the conformational and free‐energy landscape of phenylalanine transfer RNA (tRNA^Phe), a known model for RNA function, to elucidate the features that are essential in determining its stability. These studies also help explore its structural properties under extreme environmental conditions, such as low/high temperatures and high pressures. To this end, fluorescence and FTIR spectroscopies, calorimetric and small‐angle scattering measurements were carried out at different ion concentrations over a wide range of temperatures and pressures up to several hundred MPa. Compared with the pronounced temperature effect, the pressure‐dependent structural changes of tRNA^Phe are small. A maximum of only 15 % unpaired bases is observed upon pressurization up to 1 GPa. RNA unfolding differs not only from protein unfolding, but also from DNA melting. Its pressure stability seems to be similar to that of noncanonical DNA structures.     

Near-infrared spectra of water and aqueous electrolyte solutions at high pressures

The near-infrared spectra (9500 to 11000 cm^–1) of pure water and aqueous solutions of alkali halides, MgCl₂, NaClO₄, and R₄NBr were measured at temperatures between 10 and 55°C and pressures up to 500 MPa. From the analysis of the absorption spectra the following conclusions are drawn. (1) The ice I-like open structure is destroyed and the packed structure is formed as the pressure is increased. (2) The open structure of water is destroyed by the addition of alkali halides and MgCl₂ and water molecules are restricted around the ions by ion-dipole interactions. This results in a loosening of the O–H bond. (3) The perchlorate ion destroys the open structure of water and the ion-dipole interaction with water is insignificant. (4) The Bu₄N⁺ ion forms water structure around the ion similar to that of the clathrate open structure.     

智能高分子材料在智能给药系统中的应用

简要介绍了合成智能高分子材料、半合成智能高分子材料和天然智能高分子材料在智能给药系统中的应用研究进展,并展望了其在智能给药系统中的应用前景.     

智能高分子材料在智能给药系统中的应用

简要介绍了合成智能高分子材料、半合成智能高分子材料和天然智能高分子材料在智能给药系统中的应用研究进展,并展望了其在智能给药系统中的应用前景。     

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。     

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。     

Using MRI to Study High Pressure Assisted Nutrient Infusion

High pressure assisted infusion of nutrients into food was in situ monitored with magnetic resonance imaging (MRI). Modification of an off-the-shelf pressure reactor with an MRI detection circuit provided a large enough volume to accommodate food. The model food used here was peeled apple flesh as it is considered as a good mimic for fibrous food. The nuclear spin relaxation properties of the water surrounding the apple flesh were enhanced by adding paramagnetic manganese cations. In this way, MRI relaxation contrast can be used to monitor the location of doped bulk water in and around the apple flesh during pressurization. This work tracked the efficiency of pressure induced nutrient infusion in situ, demonstrating that pressure gating and ramping offer no nutrient mass transport advantage over operation at constant pressure and that the presence of a peel expectedly disrupts solute transport into the fruit. High pressure assisted infusion, with all pressurization strategies shown here, yielded nearly 100-fold faster infusion times than at ambient pressure.     

Covalent Organic Framework (COF‐1) under High Pressure

COF‐1 has a structure with rigid 2D layers composed of benzene and B₃O₃ rings and weak van der Waals bonding between the layers. The as‐synthesized COF‐1 structure contains pores occupied by solvent molecules. A high surface area empty‐pore structure is obtained after vacuum annealing. High‐pressure XRD and Raman experiments with mesitylene‐filled (COF‐1‐M) and empty‐pore COF‐1 demonstrate partial amorphization and collapse of the framework structure above 12–15 GPa. The ambient pressure structure of COF‐1‐M can be reversibly recovered after compression up to 10–15 GPa. Remarkable stability of highly porous COF‐1 structure at pressures at least up to 10 GPa is found even for the empty‐pore structure. The bulk modulus of the COF‐1 structure (11.2(5) GPa) and linear incompressibilities (k_[100]=111(5) GPa, k_[001]=15.0(5) GPa) were evaluated from the analysis of XRD data and cross‐checked against first‐principles calculations.     

Synthesis of Pyrazolines Used as Blue Organic Electroluminescence Materials

SinceTangetaldevelopedanoveltWo-layerorganicelectr0luminescentdevice(OELD)inl987successfully',OELDhasattractedmuchinterestall0verthew0rId.ltisregardedas"havingbr0ughtthethirdrev0luti0ntoflatpaneldisplay"',becauseithass0manyadvantagessuperiort0CathodeRayTube(CRT)andLiquidCrystalDevice(LCD).Ithasl0wdrivenvoltage(lO0,000cd/m=),highluminescentefficiency(l5lIn/w),goodstability(50,000h),andithassimplestructureandiseasytofabricate'.ComparedtoinorganicELD,OELDiseasie…