不同位置取代的三氰基乙烯基蒽的光谱行为的研究

本文设计合成了两个典型的共轭的电子给体与电子受体(D-A)化合物:2-三氰基乙烯基蒽(2-TCVA)与9-三氰基乙烯基蒽(9-TCVA),通过极性效应,温度效应对它们基态与激发态的光谱行为进行了表征。研究表明:这两个化合物均表现出显著的电荷转移(CT)吸收峰,分子受光激发后,9-TCVA只能在非极性溶剂中产生分子内电荷转移(ICT)态荧光,而2-TCVA在极性与非极性溶剂中都能从ICT态发光。另外,温度效应显示冻结态下,2-TCVA只发射ICT态荧光,而9-TCVA既发射类蒽(anthracene-like)荧光又发射ICT态荧光,造成这一现象的主要原因可能是2-TCVA与9-TCVA分子平面性上的差异而引起分子内电荷转移相互作用不同所致。文中还利用了Bilot-Kawski公式估算了化合物2-TCVA在激发态与基态时偶极矩的差值为18.8D。     

5位芘取代的三芳基吡唑啉化合物的光物理行为

合成了化合物 1 ,3 二苯基 5 ( 1 芘基 ) 2 吡唑啉 (DPPP) .由于 5位大取代基的存在 ,使整个分子不在同一平面 ,导致吡唑啉化合物光物理性质的改变 .DPPP光物理行为的研究表明 :即使在较低的浓度下 ( c=1 .0 8× 1 0 -5 mol·L-1) ,DPPP分子间也易生成电荷转移络合物 ;其荧光光谱表现出明显的溶剂极性效应、浓度效应和温度效应 ,不同的环境条件下可发射芘单体的荧光、分子内电荷转移络合物的荧光及分子间电荷转移络合物的荧光 .     

3,6-二(蒽醌-2-乙烯基)-N-乙基咔唑的合成及光谱性质研究

利用N-乙基咔唑和2-甲基蒽醌合成了一种A-π-D-π-A分子内电荷转移型化合物3,6-二(蒽醌-2-乙烯基)-N-乙基咔唑,并对该化合物的光化学和光物理行为进行了研究。荧光光谱表明,该化合物的发光行为对溶剂的极性非常敏感,随着溶剂极性的增大,其荧光最大发射峰有明显红移,并在强极性溶剂乙腈中出现了双荧光现象。该化合物的激发态和基态的偶极矩差值△μ为3.014D,发生了从给体(咔唑基)的N原子到分子两端受体(蒽醌)的羰基的分子内电荷转移。     

一种电荷转移型咔唑苯腙衍生物的合成及其发光行为

合成了具有强电子给体和拉电子能力基团的新化合物:9-乙基-3.-咔唑亚甲基-(2,4-二硝基)苯腙,研究了其光谱性质和光物理行为.结果表明,化合物在溶液中,随着溶剂极性的增大,发生了分子内电子转移,激发态和基态的偶极矩差值(μE-μG)为4.530 D,并在强极性溶剂中出现了有趣的双荧光发射.随着其浓度增大,会形成二聚或多聚体,荧光发射发生红移.     

三苯胺衍生物光物理性质的研究

研究了4-醛基-三苯胺(kTA)和4,4′-二醛基-三苯胺(BTA)的光谱性质。由于这两种化合物的共轭体系中既有电子给体(胺基)又有电子受体(醛基),它们在激发态发生分子内扭曲的电荷转移(TICT)。通过对FTA和BTA的荧光发射的溶剂效应、温度效应、粘度效应以及低温77K荧光的研究,发现FTA和BTA在极性溶剂中的荧光发射谱带中包含了光诱导电荷转移(ICT)和TICT(A带)2个组分,而在非极性溶剂中只有ICT带(B带),并讨论环境对TICT态的影响。另外,荧光猝灭方法也证实了这一点。     

胆甾醇修饰羟基喹啉锌的聚集诱导荧光蓝移

用稳态光谱以及皮秒瞬态荧光光谱研究了新型有机电致发光分子胆甾醇修饰羟基喹啉锌(Zn(ChQ)2)的聚集诱导荧光蓝移性质. 在Zn(ChQ)2的极性溶剂溶液中, 分子激发后会发生从胆甾醇基团向喹啉环的光致电子转移, 转移后形成了“扭转的分子内电荷转移态”作为新的荧光发射态. 而在薄膜态中, 分子由于聚集产生空间位阻, 不能形成新的荧光发射态, 相对于极性溶剂中, 产生聚集荧光增强效应, 荧光发射峰会蓝移, 发射强度会增强. 在薄膜态中, 全波长上的超快荧光衰减说明存在分子间光致能量转移过程.     

具有荧光发射能力有机化合物的光物理和光化学问题研究

有机化合物的结构、构象和环境效应对发光化合物的荧光发射具有重要的影响.本文从化合物激发态的衰变过程出发,侧重于过程的光化学与光物理问题对发光行为和机制进行讨论.如:化合物分子结构的受阻和桥键化对发光的影响;光激发下的光诱导电子和电荷转移及其相互转化;化合物扭曲的分子内电荷转移(TICT);溶剂分子和发光化合物分子间不同的相互作用及对发光的影响;在发光过程中存在着最佳的发光构象等.对于这些问题的研究和掌握,将有利于设计和合成具有高荧光量子产率的发光化合物,更好地解释在研究中出现的种种现象和在实际工作中应用它们.文章还引用了大量发光化合物作为实例,对工作中所得的结果进行了详细讨论.     

正己烷中对二烷基氨基苯甲酸的分子内电荷转移双重荧光

在非极性溶剂正己烷中,观察到了系列对二烷基氨基苯甲酸的双重荧光.皮秒激光诱导时间分辨荧光和溶剂极性效应研究证实:该双重荧光系由于激发态分子内电荷转移过程形成的电荷转移态和局部激发态所发射.超快反应动力学研究表明:在非极性溶剂中,对二烷基氨基苯甲酸分子内电荷转移过程是由较低的反应活化能所致.     

非平面分子内共轭电荷转移化合物的发光行为

合成了两种分子内共轭的电荷转移化合物:2,3二氰基-5,7-二[2-[(4-二甲氨基)-苯基]乙烯基]-6H-1,4-二氮杂卓(1)及2,3-二氰基-5-苯基-7-[2-[(4-二甲氨基)-苯基]乙烯基]-6H-1,4-二氮杂卓(2). 用UV-Vis吸收光谱和荧光光谱法对它们在不同极性溶剂中的光致变色行为进行了研究.结果表明，化合物的荧光最大发射波长与溶剂的极化参数ET(30)值可在一定范围内构成线性关系，而单臂共轭的化合物2比双臂共轭的化合物1有着更大的Stoke’s位移和基态/激发态偶极矩差.对得到的结果进行了初步的讨论.     

β-环糊精和十六烷基三甲基溴化铵混合介质中对二甲氨基苯甲醛的分子内扭转电荷转移

分子内扭转电荷转移(TICT)荧光体通常具有典型的双重荧光发射,其中短波荧光带(b带)对应正常激发态,长波荧光带(a带)对应TICT激发态。由于TICT态涉及一个完整的电荷转移,具有较大的偶极矩,其荧光发射体现出明显的溶剂极性相关性,因此适于作为一种新的荧光探针。前文已报道用对二甲氨基苯甲醛(DMABA)的TICT荧光性质研究β-环糊精(β-CD)和胶束的微环境效应。本文利用DMABA的TICT荧光性质研究了β-CD和十六烷基三甲基溴化铵(CTMAB)混合介质的性质,旨在阐明二者相互作用的特征。     

Self‐assembly of π‐conjugated bis(terpyridine) ligands with zinc(II) ions: New metallosupramolecular materials for optoelectronic applications

A series of main‐chain metallopolymers ( P1–P10 ) was prepared by the self‐assembly of rigid‐linear π‐conjugated bis(terpyridine) monomers ( 1–10 ) with Zn^II ions and was fully characterized. The polymerization was additionally confirmed by UV/vis titration experiments. A strong increase in viscosities (around 1.6 times) relative to those of the monomer solutions was found. The thermal stability of P1–P10 compared with that of 1–10 was enhanced as a result of the metallopolymerization. The electro‐optical properties of the materials were investigated in detail. Tuning of the electrochemical and photophysical properties was enabled; thus, bright purple to green photoluminescent (PL) emission (PL quantum yields of 0.12–0.81) for P1–P10 was observed in solution with the emission color strongly depending on the nature of the π‐conjugated bis(terpyridine) system. Thin homogeneous films of P6 were prepared by solution processing, that is, spin‐coating and inkjet‐printing, and exhibited intense yellow PL emission in the solid state. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4083–4098, 2009     

The Use of a Microreactor for Rapid Screening of the Reaction Conditions and Investigation of the Photoluminescence Mechanism of Carbon Dots

A microreactor is applied and reported, for the first time, in the field of research of carbon dots (CDs), including rapid screening of the reaction conditions and investigation of the photoluminescence (PL) mechanism. Various carbonaceous precursors and solvents were selected and hundreds of reaction conditions were screened (ca. 15 min on average per condition). Through analyzing the screened conditions, tunable PL emission maxima, from about 330 to 550 nm with respectable PL quantum yields, were achieved. Moreover, the relationship between different developmental stages of the CDs and the PL properties was explored by using the microreactor. The PL emission was observed to be independent of the composition, carbonization extent, and morphology/size of the CDs. This study unambiguously presents that a microreactor could serve as a promising tool for the research of CDs.     

Alternating conjugated and transannular chromophores: tunable property of fluorene-paracyclophane copolymers via transannular pi-pi interaction

[structure-see text]A series of fluorene-dithia[3.3]paracyclophane copolymers was synthesized by Suzuki coupling reactions of suitable precursors. Transannular pi-pi interactions altered the electronic and optical properties of the polymer backbone significantly. A large red shift in the emission spectrum of the unsubstituted polymer was accompanied by enhanced photoluminescence (PL) efficiency. Substitution in the cyclophane unit resulted in PL quenching.     

对苯二甲酸-铕-钇配合物的合成及荧光性质

以对苯二甲酸(H2L)为配体,合成了系列(Eu1-xYx)2L3.3H2O固体粉末配合物.通过元素分析、紫外吸收光谱、X射线衍射和红外光谱确定了配合物的组成和结构,并通过荧光光谱研究了它们的荧光性质.结果表明钇掺入配合物后,能增强Eu3+的特征荧光,当铕与钇的摩尔比为0.05∶0.95时荧光强度最强.     

Ce/Tb/Sm共掺杂CaO-B2O3-SiO2发光玻璃的白光发射及其发光颜色调控

用高温熔融法制备了Ce/Tb/Sm三元共掺杂的CaO-B2O3-SiO2发光玻璃材料,并使用荧光分光光度计和CIE色度坐标对其光谱学和发光特性进行了研究.结果表明:在374nm激发下,在Ce/Tb/Sm三元共掺杂发光玻璃的发射光谱中同时观测到了蓝光、绿光和红橙光的发射带,这些发射带的混合实现了白光的全色发射显示.此外,Ce/Tb/Sm三元共掺杂发光玻璃的发光颜色随着Tb4O7含量的减小从绿光逐渐过渡到白光,显示出发光颜色的可调节性,极大地扩展了其在白光发光二极管中的应用.     

High quantum yield photoluminescence of new polyamides containing oligo‐PPV amino derivatives and related oligomers

The synthesis and the chemical physical characterization of new photoluminescent (PL) chromophores and polymers are reported. Chromophores (oligo‐PPV symmetric derivatives ending with amino groups) are strong blue emitters with a PL quantum yield of ～70% in dioxane solution. They have been used to prepare polyamides by reaction with aliphatic acyl dichlorides in which emitting and non emitting units are alternated. PL properties of the synthesized polyamides have been evaluated in solution and reveal a strong blue emission (PL quantum yield ～60%), To increase the solubility of these systems, oligomers have been purposely prepared and then characterized. They show a peculiar white emission when excited in DMF solution; to get insight into this interesting behavior, asymmetric monoacetylated chromophores have been prepared as model compounds for the chromophoric end groups of the polyamide chains. The emission spectra of these compounds reveal a broad excimeric yellow emission which is responsible, along with the blue emission of the inner chromophoric units, of the overall white emission of the oligomers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2677–2689, 2009     

含联芴烯单元共轭聚合物的合成及表征

以六羰基钨[W(CO)₆]为催化剂, 合成了聚吲哚芴(P1)、 聚梯型四苯(P2)、 聚梯型五苯(P3)和小分子9-联吲哚芴烯(S1).该类聚合物的重复单元含有联芴烯结构, 通过芴9位的双键连接. 光学和电化学等实验结果表明, 聚合物无荧光发射, 是一类窄带隙的共轭聚合物, 其中聚合物P1薄膜的紫外吸收值最大波长为710 nm.     

Control of photoluminescence properties of CdSe nanocrystals in growth

The photoluminescence (PL) quantum yield (QY) of CdSe nanocrystals during their growth under a given set of initial conditions increases monotonically to a certain maximum value and then decreases gradually. Such a maximum is denoted as a PL "bright point", which does not always overlap with the minimum point of the PL peak width for the same reaction. The experimental results suggest that the existence of the PL bright point is a general phenomenon during the growth of semiconductor nanocrystals and likely is a signature of an optimal surface structure/reconstruction of the nanocrystals grown under a given set of initial conditions. The position of the bright point, the highest PL QY, the types of the bright points (sharp or flat), the sharpness of the PL peak, etc., were all strongly dependent on the initial Cd:Se ratio of the precursors in the solution. A large excess of the selenium precursor, with 5-10 times more selenium precursor than the amount of the cadmium precursor, was found necessary to achieve a high PL QY value and a narrow emission profile. The existence of the PL bright point and the sensitive temporal variation of the PL QY during the growth of semiconductor nanocrystals can explain the unpredictable nature and poor reproducibility of the PL properties of the as-prepared semiconductor nanocrystals observed previously. Furthermore, the knowledge gained in this study enabled us to reproducibly synthesize highly luminescent CdSe nanocrystals through a relatively simple and safe synthetic scheme. In a traditionally weak emission window for CdSe nanocrystals, the orange-red optical window, the PL QY of the as-prepared CdSe nanocrystals reached as high as 85% at room temperature, and the full width at half-maximum of the corresponding PL peak was as narrow as 23 nm, about 65-80 meV depending on the emitting position. The PL properties of the as-prepared CdSe nanocrystals are stable upon aging for at least several months. These as-prepared nanocrystals represent a series of best emitters that are highly efficient, highly pure in emission color, stable, and continuously tunable by simply varying the size of the nanocrystals.     

Composition-tunable Zn(x)Cd(1-x)Se nanocrystals with high luminescence and stability

High-quality Zn(x)Cd(1-x)Se nanocrystals have been successfully prepared at high temperature by incorporating stoichiometric amounts of Zn and Se into pre-prepared CdSe nanocrystals. With increasing Zn content, a composition-tunable emission across most of the visible spectrum has been demonstrated by a systematic blue-shift in emission wavelength. The photoluminescence (PL) properties for the obtained Zn(x)Cd(1-x)Se nanocrystals (PL efficiency of 70-85%, fwhm = 22-30 nm) are comparable to those for the best reported CdSe-based QDs. In particular, they also have good PL properties in the blue spectral range. Moreover, the alloy nanocrystals can retain their high luminescence (PL efficiency of over 40%) when dispersed in aqueous solutions and maintain a symmetric peak shape and spectral position under rigorous experimental conditions. A rapid alloying process was observed at a temperature higher than "alloying point". The mechanism of the high luminescence efficiency and stability of Zn(x)Cd(1-x)Se nanocrystals is explored.     

Sm(DBM)3phen的光致发光和电致发光性质

制备了一系列基于配合物Sm(DBM)3phen的电致发光器件. 研究了其光致发光(PL)和电致发光(EL)性质, 实验结果表明, Sm(DBM)3phen具有良好的电子注入和传输性能以及电致发光性能. 器件ITO/TPD(50 nm)/Sm(DBM)3phen(50 nm)/Alq3(30 nm)/LiF(1.0 nm)/Al的最大亮度和最大效率分别为150 cd/m2和0.72 cd/A, 器件表现为纯Sm3+离子的发光.