三种双功能光折变模型分子的合成及光谱性质研究

20世纪 90年代 ,出现了一种新型的有机光电功能材料——有机光折变材料 .由于其在高密度数据存储、全息图象加工、光放大等许多领域具有潜在的应用前景 ,因此 ,在短短的 1 0年中 ,取得了巨大进展 [1～ 3] .在众多的有机光折变材料中 ,咔唑类材料由于其优异的性能而越来越受到重视 ,成为人们研究的重点之一[4 ] .由于咔唑类材料是一类具有等电子结构的二苯胺分子 ,当在其 3-和 6 -位引入吸电子基团后 ,不仅能保持较好的电荷转移能力 ,而且还具有电光效应 .这样 ,在有机光折变材料中 ,带有吸电子基团的乙基咔唑分子既可以作为电荷载流子的传输…     

咔唑及其衍生物在蓝光OLED中的应用

咔唑及其衍生物因其特有的电学性能、电化学性能和光物理性能而被广泛研究。由于这类材料不仅可以作为良好的空穴传输材料,而且在咔唑化合物的不同位置引入电子传输修饰基团,可以使得电子和空穴更加易于注入,并且可以很好地调节两者的平衡,因此,咔唑及其衍生物被认为是一类重要的蓝光荧光材料。咔唑及其衍生物不仅可以以小分子形式应用到蓝光荧光材料、蓝光磷光材料和热致延迟荧光材料,同样可以以高分子形式应用到蓝光荧光材料中。近年来,关于咔唑及其衍生物发光材料的合成及应用成为蓝光OLED研究的热点。本文综述了近年来国内外小分子咔唑及其衍生物作为蓝光有机电致发光主体材料的研究状况,对其分子结构设计光、电子轨道结构、物理性质、热学性质、电化学性质及器件性能等方面作了详细归纳比较,同时归纳了含咔唑结构的聚合物蓝光有机电致发光材料的研究进展,最后展望了咔唑基蓝光有机电致发光主体材料的发展前景和趋势。从光电转换效率及价格方面来说,热致延迟荧光材料和聚合物(含咔唑类基团)发光材料是最具有前景的蓝光OLED材料。     

聚(2-甲氧基-5-丁氧基)对苯乙炔的合成、表征及光性能研究

１９９０年,Ｂｕｒｏｕｇｈｅｓ等［１］发现聚对苯乙炔（ＰＰＶ）类衍生物不仅是导电高分子材料,而且也是性能优良的发光材料．随后,许多科学家立即将注意力集中于这类共轭聚合物的合成及光性能的研究上,并取得了可喜的研究成果［２］．目前,对ＰＰＶ衍生物的合成,...     

《化学通报》网络版(Chemistry Online)2004年第11期论文摘要

中空纳米粒子,H2O2为氯源的醇类选择性氯化,含咔唑基团的有机光折变材料,功能性有机低分子凝胶,硝酸还原酶在壳聚糖修饰石墨上的电化学行为……     

可溶性聚对苯乙炔衍生物的合成

聚对苯乙炔（ＰＰＶ）具有独特的光电性能,经强氧化剂掺杂后是一类重要的导电材料［１］,而且具有良好的非线性光学（ＮＬＯ）性质［２］,也是目前性能最好的高分子电致发光材料［３,４］．可溶性的ＰＰＶ衍生物有望在显示领域广泛应用,从而成为电致发光领域研究的新...     

用苯乙烯共聚的方法改性含硫光学树脂的研究

自１９７２年美国ＦＤＡ制定有关配戴镜片的安全性规定以来，镜片的安全性正日益受到重视［１］．聚合物光学材料由于具有质轻、耐破损、价格便宜、易加工成型等优点［１～３］，近年来被广泛用于制作各种眼镜镜片和光学仪器的透镜［４］．对这类材料的要求除具有优良的机...     

金属氧化物/聚(N,N-二甲基苯胺)界面相互作用的ESR研究

共轭聚合物在电、光、磁等方面有很大的应用价值［１～３］,利用其研制各种实用性电子器件时,往往会涉及到它与其它材料尤其是无机半导体材料的界面复合问题［４～７］．在这些界面间,除形成一定的化学键外［８］,更多的则是伴随着电子的转移和电荷的重新分配［９,１...     

脱氯化氢法合成聚(2,5-二乙氧基对苯乙炔)

聚对苯乙炔（ＰＰＶ）及其衍生物具有独特的光电性能，经强氧化剂掺杂后是一类重要的导电材料［１］，而且具有良好的非线性光学（ＮＬＯ）性质［２］，也是目前为止性能最好的电致发光材料［３］，因而ＰＰＶ及其衍生物的合成成为电致发光领域研究的热点之一。目前国内外...     

C60接枝聚(N-乙烯基咔唑)的合成、表征及光电导性能

自从Ｃ６０被发现和被制备出来以后,其特殊的结构和独特的物理和化学性质受到各研究领域学者的广泛青睐．聚（Ｎ－乙烯基咔唑）（ＰＶＫ）体系经 Ｃ６０掺杂后光电导性能有很大幅度提高．但掺杂体系不稳定,因而限制了对该类材料的应用．为了克服这种缺点,我们尝试用各种简单的方法把Ｃ６０化学键合到高分子链中,制备具有光电导性能的Ｃ６０高分子衍生物． 最近,唐本忠［１］和 Ｐａｔｉｌ［２］等分别用常规的自由基聚合方法,将Ｃ６０接枝到聚合物分子主链上,我们已研究了不含导电高分子的Ｃ６０共聚物的光电导性能［３］,本文采用…     

用KF/Al_2O_3催化合成N-乙基咔唑方法研究

用ＫＦ／Ａｌ２Ｏ３催化合成Ｎ┐乙基咔唑方法研究钟增培周健能（中山大学化学化工学院应化系广州５１０２７５）咔唑是染料、香料、医药等产品的中间体［１］，它及其衍生物是一类杂环芳香烃化合物，有些咔唑衍生物还是很好的有机光导材料，Ｎ－乙基咔唑是合成染料硫化还...     

Gap size dependent transition from direct tunneling to field emission in single molecule junctions

I/V characteristics recorded in mechanically controllable break junctions revealed that field emission transport is enhanced in single molecule junctions as the gap size between two nanoelectrodes is reduced. This observation indicates that Fowler-Nordheim tunneling occurs not only for intermolecular but also for intramolecular electron transport driven by a reduced energy barrier at short tunneling distances.     

Spin transport properties of single metallocene molecules attached to single-walled carbon nanotubes via nickel adatoms

The spin-dependent transport properties of single ferrocene, cobaltocene, and nickelocene molecules attached to the sidewall of a (4,4) armchair single-walled carbon nanotube via a Ni adatom are investigated by using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with the spin density functional theory. Our calculations show that the Ni adatom not only binds strongly to the sidewall of the nanotube, but also maintains the spin degeneracy and affects little the transmission around the Fermi level. When the Ni adatom further binds to a metallocene molecule, its density of states is modulated by that of the molecule and electron scattering takes place in the nanotube. In particular, we find that for both cobaltocene and nickelocene the transport across the nanotube becomes spin-polarized. This demonstrates that metallocene molecules and carbon nanotubes can become a promising materials platform for applications in molecular spintronics.     

Study of molecular junctions with a combined surface-enhanced Raman and mechanically controllable break junction method

We have developed a combined surface-enhanced Raman spectroscopy (SERS) and break junction method to detect and characterize molecules between two microfabricated electrodes separated with a gap that can be continuously adjusted from a few angstroms to nanometers. It allows us to obtain a vibrational fingerprint of the adjustable molecular junction while performing electron transport measurements on the molecule simultaneously. This new approach will provide not only new insights into electron transport properties of molecule junctions on a chip but also the mechanism of single-molecule-SERS.     

Electrochemical electron transfer and its relation to charge transport in single molecule junctions

Ability to control charge transport at nanometer scale lies in the heart of design of fast reliable electronic devices. Molecular electronics thrive to use functional molecules for such transport. If the molecule contains redox center(s), a diode-like or transistor-like behavior can be easily explored by controlling not only the voltage difference between two metallic contacts of the molecular junction but also the potential of one of the contacting electrodes with respect to some reference. Thus, one needs to understand the relationship between electrochemical electron transfer and charge transport in metal–molecule–metal junctions. This review presents latest theoretical approaches toward understanding of such relationship and discusses pivotal experimental works to validate them. Tunneling and hopping pathways may operate in parallel (two-channel model), but experimental conditions dictate the channel preference.     

Molecular Design and Syntheses of Tetracyano‐5,10‐porphyrinquinodimethane Showing Stabilized LUMO

An isomer of tetracyanoporphyrinquinodimethane (TCPQ), 5,10‐TCPQ, was designed, synthesized, and structurally characterized, and its basic properties were discussed with emphasis on comparison with those of reported 5,15‐TCPQ. The title compound was synthesized by a convenient cascade reaction involving a catalyst‐free aromatic nucleophilic substitution reaction and the Uno–Takahashi reaction. The obtained π‐expanded redox molecule acted as a Wurster‐type redox molecule that underwent not only reduction but also oxidation processes. Furthermore, its absorption spectrum showed a large bathochromic shift that extended to the near‐IR region, approximately 1150 nm.     

Imaging of conformational changes of biotinylated triamide molecules covalently bonded to a carbon nanotube surface

A diamide molecule bearing a biotin terminus was bonded via an amide linkage to the surface of an aminated single-walled carbon nanotube and examined by a high-resolution transmission electron microscope. The still and movie images allowed us to study not only the conformation of the molecule but also its time evolution. An iterative sequence of modeling and simulation allowed us to assign one plausible conformation out of >10(8) possibilities. The images also provide direct support for the accepted wisdom that the curved regions of pristine carbon nanotubes are chemically reactive.     

Electronic structures and long‐range electron transfer through DNA molecules

Quantum chemical calculation on an entire molecule of segments of native DNA was performed in an ab initio scheme with a simulated aqueous solution environment by overlapping dimer approximation and negative factor counting method. The hopping conductivity was worked out by random walk theory and compared with recent experiment. We conclude that electronic transport in native DNA molecules should be caused by hopping among different bases as well as phosphates and sugar rings. Bloch type transport through the delocalized molecular orbitals on the whole molecular system also takes part in the electronic transport, but should be much weaker than hopping. The complementary strand of the double helix could raise the hopping conductivity for more than 2 orders of magnitudes, while the phosphate and sugar ring backbone could increase the hopping conductivity through the base stacks for about 1 order of magnitude. DNA could transport electrons easily through the base stacks of its double helix but not its single strand. Therefore, the dominate factor that influences the electronic transfer through DNA molecules is the π stack itself instead of the backbone. The final conclusion is that DNA can function as a molecular wire in its double helix form with the conditions that it should be doped, the transfer should be a multistep hopping process, and the time period of the transfer should be comparable with that of an elementary chemical reaction. © 2000 John Wiley & Sons, Inc. Int J Quant Chem 78: 112–130, 2000     

Controlling Single Molecule Conductance by a Locally Induced Chemical Reaction on Individual Thiophene Units

Among the prerequisites for the progress of single‐molecule‐based electronic devices are a better understanding of the electronic properties at the individual molecular level and the development of methods to tune the charge transport through molecular junctions. Scanning tunneling microscopy (STM) is an ideal tool not only for the characterization, but also for the manipulation of single atoms and molecules on surfaces. The conductance through a single molecule can be measured by contacting the molecule with atomic precision and forming a molecular bridge between the metallic STM tip electrode and the metallic surface electrode. The parameters affecting the conductance are mainly related to their electronic structure and to the coupling to the metallic electrodes. Here, the experimental and theoretical analyses are focused on single tetracenothiophene molecules and demonstrate that an in situ‐induced direct desulfurization reaction of the thiophene moiety strongly improves the molecular anchoring by forming covalent bonds between molecular carbon and copper surface atoms. This bond formation leads to an increase of the conductance by about 50 % compared to the initial state.     

丁基锡化合物与人血清白蛋白相互作用的研究

通过紫外、荧光和CD光谱, 研究了船体防污漆中主要防污成分——三丁基锡(TBT)化合物及其降解产物——一丁基锡(MBT)和二丁基锡(DBT)与人血清白蛋白(HSA)相互作用的方式与程度, 考察了浓度、酸度、有机溶剂和离子强度等因素对相互作用的影响. 结果表明, 丁基锡与HSA的相互作用是双重的, 既有丁基锡中锡离子与HSA的配位作用, 又有丁基锡中丁基基团的疏水作用, 导致HSA二级结构破坏, α-螺旋结构减少和构象转变. 一般情况下, MBT以配位作用为主, TBT以疏水作用为主, DBT两者兼而有之.     

Electron Transport through Conjugated Molecules: When the π System Only Tells Part of the Story

In molecular transport junctions, current is monitored as a function of the applied voltage for a single molecule assembled between two leads. The transport is modulated by the electronic states of the molecule. For the prototypical delocalized systems, namely, π‐conjugated aromatics, the π system usually dominates the transport. Herein, we investigate situations where model calculations including only the π system do not capture all of the subtleties of the transport properties. Including both the σ and π contributions to charge transport allows us to demonstrate that while there is generally good agreement, there are discrepancies between the methods. We find that model calculations with only the π system are insufficient where the transport is dominated by quantum interference and cases where geometric changes modulate the coupling between different regions of the π system. We examine two specific molecular test cases to model these geometric changes: the angle dependence of coupling in (firstly) a biphenyl and (secondly) a nitro substituent of a cross‐conjugated unit.