新型三苯胺-苝酰亚胺分子阵列的合成及其光学性能

以三苯胺(1),乙二胺和3,4,9,10-苝四甲酸二酐为原料,合成了一种新型的三苯胺-苝酰亚胺分子阵列(5),其结构经~1H NMR和IR表征.用UV-Vis和荧光发射光谱研究了5的光学性能,结果表明5中发生了从三苯胺基元到苝酰亚胺基元的分子内能量转移过程.     

含三苯胺结构的非对称型苝酰亚胺的合成及性能

合成了2种含有三苯胺结构的非对称型苝酰亚胺N-(2-乙基己基)-N'-(4-三苯胺)-3,4,9,10-苝二酰亚胺(PDI-ATPA)和4,4',4″-三[N-(2-乙基己基)-3,4,9,10-苝二酰亚胺]-三苯胺(PDI-TATPA).利用核磁共振谱(NMR)、红外光谱(IR)和元素分析等方法表征了2种分子的结构,采用紫外-可见(UV-Vis)吸收光谱和荧光光谱研究了其分子光物理性能及在溶液中的聚集行为,并且对分子轨道、能级和偶极矩进行了分子模拟.研究结果表明,具有星形空间对称结构的苝酰亚胺分子PDI-TATPA在溶液中具有自组装行为;引入的三苯胺结构与苝核形成电子给体-受体结构,发生分子内电子转移(PET),进而导致荧光猝灭.     

含三苯胺侧基结构的聚酰亚胺及其光致发光性能研究

通过分子结构设计,合成了2种结构相似、电子效应明显不同的含三苯胺结构二胺单体TPNDA和TPCDA.所制备的2种二胺单体分别与2种芳香型二酐(BPADA、HQDPA)进行聚合反应,并通过热酰亚胺化法制备得到4种新型聚酰亚胺薄膜.研究结果显示,4种聚酰亚胺薄膜均表现出优异的热稳定性,在紫外光照射下,含TPNDA结构的聚酰亚胺(TPNBPI、TPNHPI)没有呈现荧光特性,而含TPCDA结构的聚酰亚胺(TPCBPI, TPCHPI)均可发明显的橙色荧光.对模型化合物的理论计算结果表明,共轭的TPNDA体系及不共轭的TPCDA体系均应为跃迁禁阻的不发光体系.进一步的研究表明,含TPCDA结构的聚酰亚胺体系的发光性质主要源于以下两方面原因:(1)与N原子相比,sp3的碳原子隔断了三苯胺结构与聚合物主链酰亚胺环的共轭性,有利于消除聚酰亚胺分子内电荷转移效应对三苯胺(TPA)侧基的影响;(2)相对独立的侧基TPA可与聚酰亚胺分子主链之间发生强的分子间相互作用,该相互作用可导致该体系发射较强的橙色荧光.其最大发射发光波长红移达184 nm,且发光强度明显增强.     

含有p-n单元的苝聚酰亚胺的合成及其敏化光电池的性能研究

设计、合成并表征了含有p-n(供电子-吸电子)单元的苝聚酰亚胺PPI, 并研究了其作为敏化电极材料的光电池的性能. 产物为非晶态. 从电子谱中计算出其能带带宽为2.16 eV, 用电化学循安伏安法计算得到其电子亲和势(E_a, 最低空轨道能级)为－3.97 eV, 离子势(IP, 最高占据轨道能级的绝对值)为6.13 eV, 其能级与二氧化钛的能级相匹配, 对二氧化钛有较好的敏化作用. 光电池的光电流作用谱(IPCE)与紫外电子谱十分相似, 光电压与光强之间有指数的关系. 用苝聚酰亚胺为敏化剂的光电池的光电转换效率为0.0135%.     

含聚二甲硅氧烷短支链的聚酰亚胺的合成及其透氧性的研究

介绍了在甲撑二苯胺的亚甲基上接上聚二甲基硅氧烷短链，并用含二甲硅氧烷短链的二苯胺单体和均苯甲酸二酐反应制取聚酰亚胺的方法。实验结果表明，在含硅量相同的情况下，支链型的改性聚酰亚胺的机械强度高。     

有机染料敏化纳米晶太阳能电池

本文综述了有机染料敏化纳米晶太阳能电池的研究现状,简要介绍了有机染料敏化纳米晶太阳能电池的结构和工作原理以及氧化物电极、对电极和电解质的设计思路和制备情况。重点介绍了有机染料的研究现状,包括香豆素类染料、多烯类染料、噻吩类染料、天然染料、半花菁类染料、卟啉类染料、三苯胺类染料、苝类染料等。同时讨论了若干影响有机染料敏化太阳能电池性能的因素,提出了提高光电转换效率的设想与对策,对未来的发展进行了展望。     

可见光响应Fe3+-聚酰亚胺网络的合成及光诱导自由基聚合

将清洁、安全的太阳能(尤其是可见光)转化为化学能以合成高分子材料,一直是光催化领域的研究热点和难点.其关键问题是发展新型光催化材料,提升其在高分子合成环境下的光催化活性及稳定性.由于共轭微孔聚合物网络的独特优点,例如光电性能易调控、比表面积高以及结构相对稳定等,在光催化领域应用日益广泛.与其它共轭微孔聚合物网络相比,聚酰亚胺网络具有更高的光稳定性和耐化学腐蚀能力;同时,可用于合成聚酰亚胺网络的单体丰富,合成方法可靠,易于从分子层面调控其光电活性,提升其光催化活性.由于以上优点,基于聚酰亚胺网络的光催化体系在光诱导合成高分子材料领域展现出良好的应用前景.然而在实际应用中,聚酰亚胺网络却面临光催化活性不足的困扰.为解决此问题,本研究组曾设计,合成了以4,4',4'-三氨基三苯胺为核的聚酰亚胺网络,利用4,4',4'-三氨基三苯胺的给电子能力,促进聚酰亚胺网络中光生电子/空穴对的分离,有效提升了聚酰亚胺网络在可见光作用下对水相中有机污染物的光降解效率.在已有工作的基础上,本文设计、合成出一种新型聚酰亚胺网络,并通过配位作用,在聚酰亚胺网络网络中引入Fe^3+离子掺杂,提升其光催化性能,在有机环境中实现可见光诱导自由基聚合.首先,以三聚氰胺为电子给体单元,以1,4,5,8-萘四甲酸二酐为电子受体单元,通过酰亚胺缩聚反应构建出含电子给体-受体交替结构的聚酰亚胺网络(MPI);然后,通过浸渍法将Fe^3+离子引入到MPI网络内,制备出Fe^3+-聚酰亚胺网络(Fe@MPI).通过傅里叶变换红外光谱,粉末X射线衍射(XRD)和X射线光电子能谱对Fe@MPI的结构进行表征.结果显示,Fe^3+主要通过配位键的形式与MPI网络结合.同时,结合XRD谱图与扫描电子显微镜和透射电子显微镜结果可见,Fe^3+并非以氧化物或其它铁盐的形式简单地沉积在聚酰亚胺网络上,而是以Fe^3+-MPI配位作用均匀分布在MPI网络内.此外,XRD及氮气吸附实验结果表明,引入Fe^3+会破坏MPI网络的有序程度,导致复合材料的结晶度下降,但并不影响其多孔结构.通过紫外漫反射光谱和光电流谱对Fe@MPI的光吸收能力和光生电子/空穴对分离能力进行表征,结果显示,MPI网络与Fe^3+配位后,其光谱响应范围可拓宽至1250 nm,而其光电流响应强度也较纯MPI提升了3.5倍,表明引入Fe^3+配位可有效促进光生电子/空穴对的分离.基于其优异的光电性能,我们以Fe@MPI为光催化剂,在30℃下实现了甲基丙烯酸甲酯的可见光诱导自由基聚合,制备出分子量可达31.3×10^4 g mol^-1的聚甲基丙烯酸甲酯.同时,与MPI和FeCl3相比,Fe@MPI在相同条件下具有更高的催化效率,与其光电性能相吻合.最后,催化剂回收、循环实验表明,Fe@MPI易于回收,且具有良好的结构和性能稳定性:四次循环实验后,其结构和光催化活性均可基本保持不变.     

光电导性聚酰亚胺的研究（Ⅰ）：含咔唑,酞菁铜聚酰亚胺的合…

通过缩聚反应制备了含咔唑，酞菁铜的聚酰胺酸，利用热处理方法使之转化为相应的聚酰亚胺。热失重分析表明所制备的聚酰亚胺具有很好的稳定性能，在空气中的起始分解温度为５３０℃。红外光谱分析证实所采用的热处理方法能使聚酰胺酸转化为聚酰亚胺，以含酞菁酮，咔唑基团的聚酰亚胺为光生层时，光电导性能明显优于酞菁酮，为光生层的光电导体系。     

含聚二甲基硅氧烷短支链的聚酰亚胺的合成及其透氧性的研究

介绍了在甲撑二苯胺的亚甲基上接上聚二甲基硅氧烷短链，并用含二甲基硅氧烷短链的二苯胺单体和均苯四甲酸二酐反应制取聚酰亚胺的方法。实验结果表明，在含三硅量相同的情况下，支链型的改性聚酰亚胺的机械强度高。氧的透过系数随支链长度的增加而增加，当二甲基硅氧烷短链的硅原子由１增加到４时，透氧系数由３．６５Ｂａｒｒｅ增加到１２．０Ｂａｒｒｅ，而Ｏ２／Ｎ２分离系数则由６．４降到３．５。     

以苝酰亚胺为构筑单元的氢键型超分子聚合物的组装与应用

以苝酰亚胺为构筑单元的氢键型超分子聚合物具有动态可逆的特征和独特的聚集体结构,呈现出许多新颖的光电功能特性,在有机太阳能电池,场效应晶体管和光收集材料等高新技术领域有着广阔的应用前景。本文在介绍苝酰亚胺衍生物的化学结构及其氢键组装特点的基础上,主要综述了近年来以苝酰亚胺为构筑单元,采用三重氢键,多重氢键以及其他形式氢键引导构筑的超分子聚合物的研究动态,这类超分子聚合物展示了丰富的组装体形貌结构,独特的性质功能以及在光电功能器件上的广阔的应用前景。最后,对其发展前景作了展望。     

1,4-Benzene-bridged covalent hybrid of triarylamine and cyclometalated ruthenium: a new type of organic-inorganic mixed-valent system

A 1,4-benzene-bridged covalent hybrid of triarylamine and cyclometalated ruthenium 1(2+) was isolated as a bench-stable open-shell substance. The free spin in this complex is mainly associated with the triarylamine unit, as indicated by EPR and DFT calculations and electrochemical analysis. It exhibits an intense intervalence-charge-transfer transition around 1050 nm that is not present in 1(+) and 1(3+).     

具有高分子空穴传输性能的含三芳胺侧链接枝聚苯乙烯的合成与表征

三芳胺类聚合物作为空穴传输材料具有广泛的应用前景。设计、合成了一种新的三芳胺衍生物单体 4 -乙烯基苄氧基亚甲基三苯胺 ,通过NMR、IR及MS等手段对其结构进行了表征。用AIBN引发新单体进行自由基聚合反应 ,得到了侧链带三苯胺基团的高分子空穴传输聚合物 ,该聚合物具有较高玻璃化转变温度及高热稳定性。     

Hydrogen-bonding effects on the formation and lifetimes of charge-separated States in molecular triads

Photoinduced electron transfer in two molecular triads comprised of a triarylamine donor, a d(6) metal diimine photosensitizer, and a 9,10-anthraquinone acceptor was investigated with particular focus on the influence of hydrogen-bonding solvents on the electron transfer kinetics. Photoexcitation of the ruthenium(II) and osmium(II) sensitizers of these triads leads to charge-separated states containing an oxidized triarylamine unit and a reduced anthraquinone moiety. The kinetics for formation of these charge-separated states were explored by using femtosecond transient absorption spectroscopy. Strong hydrogen bond donors such as hexafluoroisopropanol or trifluoroethanol cause a thermodynamic and kinetic stabilization of these charge-separated states that is attributed to hydrogen bonding between alcoholic solvent and reduced anthraquinone. In the ruthenium triad this effect leads to a lengthening of the lifetime of the charge-separated state from ～750 ns in dichloromethane to ～3000 ns in hexafluoroisopropanol while in the osmium triad the respective lifetime increases from ～50 to ～2000 ns between the same two solvents. In both triads the lifetime of the charge-separated state correlates with the hydrogen bond donor strength of the solvent but not with the solvent dielectric constant. These findings are relevant in the greater context of solar energy conversion in which one is interested in storing light energy in charge-separated states that are as long-lived as possible. Furthermore they are relevant for understanding proton-coupled electron transfer (PCET) reactivity of electronically excited states at a fundamental level because changes in hydrogen-bonding strength accompanying changes in redox states may be regarded as an attenuated form of PCET.     

Electrochemical and optical characterization of triarylamine functionalized gold nanoparticles

This paper describes the synthesis, structural analysis, and investigations of the optical and electrochemical properties of some gold nanoparticles (AuNPs) which consist of a triarylamine ligand shell attached to small gold cores (Au-Tara). The triarylamine chromophores were attached to small 4-bromobenzenethiol covered gold nanoparticles (ca. 2 nm in diameter) by Sonogashira reaction. This procedure yields triarylamine redox centers attached via π-conjugated bridging units of different length to the gold core. The AuNPs were analyzed with (1)H NMR spectroscopy, diffusion ordered NMR spectroscopy (DOSY), thermogravimetric analysis (TGA), and scanning transmission electron microscopy (STEM). Cyclic voltammetry (CV) technique was used to determine the composition of the redox active particles via the Randles-Sevcik equation. The optical and electrochemical properties of the Au-Tara nanoparticles and of their corresponding unbound ligands (Ref) were investigated with UV/vis/NIR absorption spectroscopy, Osteryoung square wave voltammetry (OSWV), and spectroelectrochemistry (SEC). These data show that the assembling of triarylamines in the vicinity of a gold nanoparticle can change the optical and electrochemical properties of the triarylamine redox chromophores depending on the kind and length of the bridging unit. This is due to gold core-chromophore and chromophore-chromophore interactions.     

Electrogenerated chemiluminescence. 81. Influence of donor and acceptor substituents on the ECL of a spirobifluorene-bridged bipolar system

The electrochemistry and radical ion annihilation electrogenerated chemiluminescence (ECL) of 9,9'-spirobifluorene-bridged bipolar systems containing 1,3,4-oxadiazole-conjugated oligoaryl and triarylamine substituents were investigated. The stability of the oxidized spirobifluorenes was improved by functionalization with triarylamine centers. These donor-acceptor (DA) compounds exhibited a good fluorescence efficiency with an emission maximum that correlated with the potential difference between radical anion and cation formation, suggesting a charge transfer (CT) emission band. An ECL mechanism based on the formation of the CT excited state by radical ion annihilation or production of the triplet state followed by triplet-triplet annihilation, with perhaps some excimer contribution, is proposed.     

Poly(propylene imine) dendrimers as hydrogen donor in Type II photoinitiated free radical polymerization

Three generations of poly(propylene imine) dendrimers, namely (PPI-16, PPI-32 and PPI-64; 16, 32 and 64 for generations 3, 4 and 5, respectively) were used as hydrogen donors in photoinitiated free radical polymerization of methyl methacrylate by using one of the following photosensitizers; benzophenone and thioxanthone. The effect of generation number of the dendrimer on photoinitiation efficiency and molecular weight of the resulting polymers was investigated. Glass transition temperatures and particle size measurements of the resulting polymers indicated the presence of nearly stretched polymer chains around the dendrimers. The location of hydrogen donating sites was evaluated by photolysis studies in the absence of monomer by using a stable radical namely, 2,2,6,6-tetramethylpiperidine-N-oxyl free radical (TEMPO) and showed that hydrogen abstraction occurs from the inner tertiary amino groups. The TEMPO attached dendrimers were further used in the nitroxide mediated radical polymerization (NMP) of styrene to yield star polymers.     

Syntheses and spectroscopic studies of spirobifluorene-bridged bipolar systems; photoinduced electron transfer reactions

Some 9,9'-spirobifluorene-bridged bipolar systems 1-3 containing 1,3,4-oxadiazole-conjugated oligoaryl and triarylamine moieties have been synthesized, in which 1 exhibits remarkable solvent-polarity dependent fluorescence properties due to a highly efficient photoinduced electron transfer reaction.     

Photoinduced electron transfer in linear triarylamine-photosensitizer-anthraquinone triads with ruthenium(II), osmium(II), and iridium(III)

A rigid rod-like organic molecular ensemble comprised of a triarylamine electron donor, a 2,2'-bipyridine (bpy) ligand, and a 9,10-anthraquinone acceptor was synthesized and reacted with suitable metal precursors to yield triads with Ru(bpy)(3)(2+), Os(bpy)(3)(2+), and [Ir(2-(p-tolyl)pyridine)(2)(bpy)](+) photosensitizers. Photoexcitation of these triads leads to long-lived charge-separated states (τ = 80-1300 ns) containing a triarylamine cation and an anthraquinone anion, as observed by transient absorption spectroscopy. From a combined electrochemical and optical spectroscopic study, the thermodynamics and kinetics for the individual photoinduced charge-separation and thermal charge-recombination events were determined; in some cases, measurements on suitable donor-sensitizer or sensitizer-acceptor dyads were necessary. In the case of the ruthenium and iridium triads, the fully charge-separated state is formed in nearly quantitative yield.     

Detecting the adsorption of dye molecules in homogeneous poly(propylene imine) dendrimer monolayers by surface plasmon resonance sensor

In this work, we studied guest-host interactions between various dye molecules and the fifth-generation poly(propylene imine) (PPI-5) dendrimers in aqueous solutions using a surface plasmon resonance (SPR) sensor. The effect of the properties of guest and host molecules (e.g., charge and shape) and media (e.g., pH and ion strength) on affinity between guest and host molecules was investigated. Based on an immobilized homogeneous monolayer of PPI-5 dendrimer tethered to carboxyl-terminal self-assembled monolayers, the adsorption behavior of a group of dye molecules in PPI-5 was obtained. Results show that the strong affinity of PPI-5 to Rose Bengal and erythrosine B is attributed to the good match in charge and shape between the cavities of the dendrimer and the dye molecules. Maximum adsorption around a pH value of 7 was observed. The kinetic behaviors of different dye molecules in dendrimers were also studied. A fundamental understanding of guest-host interactions in dendrimers will guide the design of new-generation sensors and drug delivery carriers.     

2.2]paracyclophane-bridged mixed-valence compounds: application of a generalized Mulliken-Hush three-level model

A series of [2.2]paracylophane-bridged bis-triarylamine mixed-valence (MV) radical cations were analyzed by a generalized Mulliken-Hush (GMH) three-level model which takes two transitions into account: the intervalence charge transfer (IV-CT) band which is assigned to an optically induced hole transfer (HT) from one triarylamine unit to the second one and a second band associated with a triarylamine radical cation to bridge (in particular, the [2.2]paracyclophane bridge) hole transfer. From the GMH analysis, we conclude that the [2.2]paracyclophane moiety is not the limiting factor which governs the intramolecular charge transfer. AM1-CISD calculations reveal that both through-bond as well as through-space interactions of the [2.2]paracyclophane bridge play an important role for hole transfer processes. These electronic interactions are of course smaller than direct pi-conjugation, but from the order of magnitude of the couplings of the [2.2]paracyclophane MV species, we assume that this bridge is able to mediate significant through-space and through-bond interactions and that the cyclophane bridge acts more like an unsaturated spacer rather than a saturated one. From the exponential dependence of the electronic coupling V between the two triarylamine localized states on the distance r between the two redox centers, we infer that the hole transfer occurs via a superexchange mechanism. Our analysis reveals that even significantly longer pi-conjugated bridges should still mediate significant electronic interactions because the decay constant beta of a series of pi-conjugated MV species is small.