小分子蓝色磷光主体材料

有机电致发光器件是有机光电子领域的研究热点,在平板显示和固体照明领域有着广阔的应用前景.目前,由于器件效率和稳定性的问题,蓝色磷光器件是有机电致发光器件的瓶颈,而蓝色磷光主体材料的选择是影响蓝色磷光器件性能的关键因素.综述了小分子蓝色磷光主体材料的最新研究进展,重点介绍了各类小分子蓝色磷光主体材料的设计思想、器件性能.包括空穴传输性主体材料、含硅主体材料、电子传输性主体材料、双极主体材料和可湿法加工的蓝色磷光小分子主体材料的结构、特点及相应器件性能.最后对小分子蓝色磷光主体材料的发展方向进行了展望.     

生物形态的高性能材料

经过长期进化,生物质已经形成了复杂的分级胞状结构.这些结构为生物体生长和发育提供了传输水分和营养物质的快速通道.由生物质转化形成的高性能材料,不仅保持了材料本身的优良性质,而且还具有生物质的宏观形貌和微观结构特征.由于具有丰富的分级多孔结构和优良的机械性能,生物形态材料在催化、分离与吸附和高温尾气处理等领域具有广泛的应用前景.目前,各种不同类型的生物质已被广泛用来制备生物形态的高性能材料.本文结合国内外研究进展综述了生物形态材料的制备技术、材料种类以及应用情况.     

生物形态的高性能材料

经过长期进化,生物质已经形成了复杂的分级胞状结构.这些结构为生物体生长和发育提供了传输水分和营养物质的快速通道.由生物质转化形成的高性能材料,不仅保持了材料本身的优良性质,而且还具有生物质的宏观形貌和微观结构特征.由于具有丰富的分级多孔结构和优良的机械性能,生物形态材料在催化、分离与吸附和高温尾气处理等领域具有广泛的应用前景.目前,各种不同类型的生物质已被广泛用来制备生物形态的高性能材料.本文结合国内外研究进展综述了生物形态材料的制备技术、材料种类以及应用情况.     

四唑类化合物的合成及应用研究新进展

四唑是一种重要的五元芳杂环,具有多氮富电子的平面结构特征.这种特殊的结构使得四唑类化合物作为药物、炸药、功能材料等在医学、农学、材料科学等众多领域具有广泛的应用前景.相关研究十分活跃,已取得了许多重要进展.结合作者唑类方面的研究,参考国内外近五年文献,系统地综述了四唑类化合物的合成及其在医药、农药、材料等领域的应用研究新近况.     

罗丹明类荧光染料的合成及应用

本文综述了近年罗丹明类荧光染料的研究进展,详细介绍了它们的结构特征、设计思路、合成方法、目前效果及在生物分析检测领域的应用,并对其未来的发展进行了展望.     

前手性酮的不对称还原制备线形光活性二级醇

在液晶显示器制造工艺中,为了防止反扭曲现象的发生,要在液晶中加入少量光活性物质以改善显示器的性能[1～3].为了保证主体液晶的使用性能不受添加剂的影响,通常使用螺旋扭曲能力较大的光活性材料以减少添加剂的用量,同时还要求光活性材料的螺距随温度的变化率要小.目前,符合上述要求的光活性添加剂大多为含有苯环或环己烷环或两种环均有的棒状结构的醇类或酯类化合物.因此研究具有上述结构特征的前手性酮的不对称还原在液晶材料的研究中具有十分重要的意义.     

含菲并咪唑基团的蓝色电致发光材料

菲并咪唑作为一类新型的蓝色荧光材料的构筑基元, 其以合适的禁带宽度、 较高的发光效率、 优异的光热稳定性和相对平衡的载流子注入和传输能力, 引起广泛关注. 发展性能优良的蓝光材料对有机电致发光器件的进一步应用十分重要. 本文综述了近年来基于菲并咪唑基团的蓝色电致发光材料的研究进展, 系统地介绍了菲并咪唑基团的结构特征以及各类衍生物的器件性能, 展望了这类化合物在电致发光领域的应用前景.     

蓝色磷光有机发光材料

有机发光二极管在信息显示和固体照明领域具有广阔的应用前景,二十多年来得到了广泛关注,取得了很大进展。但显示和照明必需的蓝色发光材料,特别是蓝色磷光材料是目前有机发光材料研究领域的瓶颈,其稳定性和效率亟待提高。本文总结了近年来蓝色磷光有机发光材料的研究进展,系统介绍了蓝色磷光染料和主体材料这两大类材料的分子设计思想和发展动态,以及它们在有机发光二极管中的应用,并对蓝色磷光有机发光材料未来的研究方向进行了展望。     

生物形态的高性能材料

经过长期进化,生物质已经形成了复杂的分级胞状结构。这些结构为生物体生长和发育提供了传输水分和营养物质的快速通道。由生物质转化形成的高性能材料,不仅保持了材料本身的优良性质,而且还具有生物质的宏观形貌和微观结构特征。由于具有丰富的分级多孔结构和优良的机械性能,生物形态材料在催化、分离与吸附和高温尾气处理等领域具有广泛的应用前景。目前,各种不同类型的生物质已被广泛用来制备生物形态的高性能材料。本文结合国内外研究进展综述了生物形态材料的制备技术、材料种类以及应用情况。     

摩阻材料用亚麻油改性酚醛树脂的制备及耐热性研究

利用亚麻油改性酚醛树脂,得到高性能的摩阻材料用树脂基体.推导了改性机理和结构特征,并进行了耐热试验和分析.结果表明,亚麻油参与了反应并成为聚合物的一部分,亚麻油改性酚醛树脂固化后的结构特征是互穿聚合物网络(IPN),与普通酚醛树脂相比,亚麻油改性酚醛树脂的耐热性能显著提高,可望用作耐高温磨阻材料树脂基体.     

掺杂发光有机电致磷光器件工作原理及主体材料

本文总结了基于掺杂发光的有机电致磷光器件(PhOLED)中磷光材料被激发的途径及机理,并指出不同主体材料对器件性能的不同影响.全面介绍了小分子主体材料研究的新进展及它们在PhOLEDs器件中的运用.比较和讨论了基于各种不同性质主体材料的器件性能,指出主体材料选择策略.同时讨论了各类主体材料的分子结构、热稳定性、三线态能级、载流子迁移率及HOMO/LUMO能级之间的关系,揭示了上述特性对器件性能影响.     

Bipolar Host Materials for Organic Light‐Emitting Diodes

It is important to balance holes and electrons in the emitting layer of organic light‐emitting diodes to maximize recombination efficiency and the accompanying external quantum efficiency. Therefore, the host materials of the emitting layer should transport both holes and electrons for the charge balance. From this perspective, bipolar hosts have been popular as the host materials of thermally activated delayed fluorescent devices and phosphorescent organic light‐emitting diodes. In this review, we have summarized recent developments of bipolar hosts and suggested perspectives of host materials for organic light‐emitting diodes.     

Molecular hosts for triplet emitters in organic light-emitting diodes and the corresponding working principle

This paper summarizes the mechanism and routes for excitation of triplet emitters in dopant emission based phosphorescent organic light-emitting diodes (PhOLEDs), providing a comprehensive overview of recent progress in molecular hosts for triplet emitters in PhOLEDs. Particularly, based on the nature of different hosts, e.g., hole transporting, electron transporting or bipolar materials, in which the dopant emitters can be hosted to generate phosphorescence, the respective device performances are summarized and compared. Highlights are given to the relationships among the molecular structure, thermal stability, triplet energy, carrier mobility, molecular orbital energy level and their corresponding device performances.     

Benzimidazobenzothiazole‐Based Bipolar Hosts to Harvest Nearly All of the Excitons from Blue Delayed Fluorescence and Phosphorescent Organic Light‐Emitting Diodes

Much effort has been devoted to developing highly efficient organic light‐emitting diodes (OLEDs) that function through phosphorescence or thermally activated delayed fluorescence (TADF). However, efficient host materials for blue TADF and phosphorescent guest emitters are limited because of their requirement of high triplet energy levels. Herein, we report the rigid acceptor unit benzimidazobenzothiazole (BID‐BT), which is suitable for use in bipolar hosts in blue OLEDs. The designed host materials, based on BID‐BT, possess high triplet energy and bipolar carrier transport ability. Both blue TADF and phosphorescent OLEDs containing BID‐BT‐based derivatives exhibit external quantum efficiencies as high as 20 %, indicating that these hosts allow efficient triplet exciton confinement appropriate for blue TADF and phosphorescent guest emitters.     

Wireless Electrochemical Actuation of Conducting Polymers

Electrochemical actuation of conducting polymers usually requires a direct connection to an electric power supply. In this contribution, we suggest to overcome this issue by using the concept of bipolar electrochemistry. This allows changing the oxidation state of the polymer in a gradual and wireless way. Free‐standing polypyrrole films were synthesized with an intrinsic morphological asymmetry of their two faces in order to form a bilayer structure. Immersing such objects in an electrolyte solution and exposing them to a potential gradient leads to the asymmetric oxidation/reduction of the polymer, resulting in differential shrinking and swelling along the main axis. This additional asymmetry is responsible for a structural deformation. Optimization allowed highly efficient bending, which is expected to open up completely new directions in the field of actuation due to the wireless mode of action.     

Molecular dynamics simulations of matrix deposition. III. Site structure analysis for porphycene in argon and xenon

Porphycene (1) and porphyrin (2), two constitutional isomers, reveal completely different electronic spectral patterns in argon and xenon matrices. For the former the spectra recorded in the two solidified gases resemble each other, whereas for the latter they are completely different. This difference can be rationalized by molecular-dynamics simulations of the structure of the microenvironment carried out for the two chromophores embedded in argon and xenon hosts. For 1, the structure of the main substitutional site is the same for Ar and Xe and consists of a hexagonal cavity obtained by removing seven host atoms from the [111] crystallographic plane. An analogous structure is obtained for 2 in xenon. However, in argon the porphyrin chromophore environment is shared between several different sites, with the number of replaced host atoms ranging from seven to ten. These results demonstrate that a relatively minor structural alternation may lead to major changes in the spectral pattern of molecules embedded in rare-gas cryogenic matrices.     

Optical properties of stretched polymer dispersed liquid crystal films

The basic mechanisms determining the formation of optical anisotropy in stretched, thin polymer dispersed liquid crystal (PDLC) films with micron sized nematic droplets have been studied experimentally and the results analysed in terms of a proposed theoretical model. The experiments were performed on PDLC films with the bipolar nematic director configuration in the droplets, where the film transmittance, microscopic structure, and birefringence of the polymer matrix were studied. It is shown that the orientational ordering of bipolar nematic droplets, introducing the main contribution to the ability of stretched PDLC film to polarize the transmitted light, is strongly dependent upon initial droplet shape and the elastic properties of the polymer matrix. The 'anomalous' nematic director orientation is also observed in a portion of elongated droplets where the axes of bipolar configurations do not coincide with the major axes of the droplet cavities due to the presence of inclusions at the cavity walls. The effect of alternation of droplet size and shape upon stretching and the influence of optical anisotropy of the polymer matrix on film transmittance are analysed. On the basis of the results obtained, simple criteria for optimization of main PDLC polarizer performance are formulated.     

Structure-activity relationships in the acceleration of a hetero Diels-Alder reaction by metalloporphyrin hosts

At 0.33 mM in dichloromethane at 25 degrees C the cyclic metalloporphyrin hosts 5, 7, 8, and 10 accelerate 12-fold, 260-fold, 1130-fold, and 250-fold, respectively, the reaction of 1 and 2 and also bind the product 3 very strongly. These observations combined with previously measured results with hosts 6, 9, and 11 allowed us to explore the influence of host geometry changes on acceleration rates and product binding over a wide range of host molecules of different size, ranging from extremely tightly strapped to very relaxed. To estimate the Zn-Zn distance in the transition-state complex, we carried out quantum mechanical calculations (at the HF/6-31G level) for the transition state to form 3. The structure-activity relationships found for hosts 5-11, along with the structural features calculated for the transition-state structure between 1 and 2 and previously crystallographically observed for product-free hosts and for a host.product complex,(4) suggest that both host preorganization as well as host flexibility are key features leading to high acceleration rates and product binding and that it is the delicate balance between the two structural features that leads to maximum efficiency.     

Recognition of mandelate stereoisomers by chiral porphyrin hosts: prediction of stereopreference in guest binding a priori using a simple binding model?

Rigid porphyrin hosts that mimic the spatial arrangement of mandelate recognition motifs lead to stereoselective receptors and illustrate how subtle structural differences in host design have significant impact on guest recognition. The porphyrin hosts are obtained with minimal synthetic effort from readily available chiral amine precursors and are modular in design. The chiral recognition properties of the porphyrin-based hosts with chiral carboxylate-containing guests and chiral amines are described. UV/vis and ¹H NMR spectroscopic results indicate some of these porphyrin hosts undergo an induced fit conformational change upon guest binding.     

Phosphine Sulfide-Based Bipolar Host Materials for Blue Phosphorescent Organic Light-Emitting Diodes

Three phosphine sulfide-based bipolar host materials, viz CzPhPS, DCzPhPS, and TCzPhPS, were facilely prepared through a one-pot synthesis in excellent yields. The developed hosts exhibit superior thermal stabilities with the decomposition temperatures (T_d) all exceeding 350 °C and the melting temperatures (T_m) over 200 °C. In addition, their triplet energy (E_T) levels are estimated to be higher than 3.0 eV, illustrating that they are applicable to serve as hosts for blue phosphorescent organic light-emitting diodes (PhOLEDs). The maxima luminance, current efficiency (CE), power efficiency (PE), and external quantum efficiency (EQE) of 17,223 cd m⁻², 36.7 cd A⁻¹, 37.5 lm W⁻¹, and 17.5% are achieved for the blue PhOLEDs hosted by CzPhPS. The PhOLEDs based on DCzPhPS and TCzPhPS show inferior device performance than that of CzPhPS, which might be ascribed to the deteriorated charge transporting balance as the increased number of the constructed carbazole units in DCzPhPS and TCzPhPS molecules would enhance the hole-transporting ability of the devices to a large extent. Our study demonstrates that the bipolar hosts derived from phosphine sulfide have enormous potential applications in blue PhOLEDs, and the quantity of donors should be well controlled to exploit highly efficient phosphine sulfide-based hosts.