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 .     

基于苯炔苯及荧光探针芘自组装单分子膜的制备及苯胺检测

利用重氮基的光分解活性、采用自组装的方法将带有功能基团NH₂ 的4-(4-氨基苯乙炔基)苯共价键接在石英基片上制备了共轭单分子膜; 利用膜上NH₂ 的反应活性, 通过酰胺化反应或自组装的方式将稠环芘修饰在单分子膜上,构筑了含有芘荧光探针的稳定发光超薄膜; 该薄膜能够与电子受体硝基苯胺间因相互作用形成电荷转移络合物而使其荧光猝灭, 并且该薄膜对硝基苯胺同分异构体的荧光猝灭响应有明显的差异, 其中对硝基苯胺对功能薄膜的猝灭效应最为明显, 其次是邻硝基苯胺和间硝基苯胺; 且具有明显的浓度依赖性.     

荧光可视化技术在食品分析中的应用进展

介绍了常见的荧光可视化传感器(比率、纸基、分子印迹荧光传感器),荧光可视化传感机制(荧光共振能量转移、内滤效应、光诱导电子转移、聚集诱导猝灭、聚集性诱导发射、分子内电荷转移、金属-配体电荷转移等)及其判定方法，综述了量子点(普通量子点和生物质量子点)、有机荧光物质和金属荧光纳米团簇等发光物质作为荧光可视化探针在食品分析中的应用，并对其发展前景进行了展望(引用文献69篇)。     

芘-环八四噻吩衍生物的合成与发光现象研究

环八四噻吩(COTh)是一类新发现的具有聚集诱导发光(AIE)特性的"马鞍型"分子.将发光基团芘引入到COTh分子骨架,设计合成了三种芘-环八四噻吩化合物,即单芘基环八四噻吩(Py-COTh)、四芘基环八四噻吩(4Py-COTh)以及四(三(三甲硅基)环八四噻吩基)芘(12TMS-4COTh-Py).考察了它们的吸收光谱、溶液态与冻结态(77K)下的荧光光谱以及聚集诱导发光(AIE)行为.研究发现COTh分子骨架上芘基数量的增加对分子的共轭效应影响较小,但其单分子与聚集态的发光行为显著增强且发光峰位红移;而芘基骨架上COTh基团数量的增加,增加了分子的共轭效应,造成了吸收光谱与荧光发射光谱峰位的大范围红移.这些光物理现象与分子结构存在着显著的构效关系.     

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。     

芘荧光探针光法测定聚氧化乙烯与SDS的作用

采用芘荧光法研究了聚氧化乙烯(PEO)与十二烷基硫酸钠(SDS)在不同质量浓度的水溶液中的相互作用。以芘单体的荧光光谱第一峰与第三峰的荧光强度之比(I_1/I_3)及激基缔合物与单体荧光强度之比(I_E/I_M)来探测芘分子所处环境的极性。结果表明:Py-PEO-SDS水溶液在极小质量浓度下基本不形成疏水微区,当质量浓度超过一定值时开始大量形成疏水微区,I_1/I_3值迅速下降。在溶液浓度为6g·L~(-1)时,SDS分子开始与聚合物分子相互作用,芘探针分子开始与形成的预胶束发生吸附作用,同时开始形成高荧光电子产率的激基缔合物;在溶液浓度为20g·L~(-1)时,随着SDS溶液浓度的增加,芘探针分子全部进入胶束中,形成的激基缔合物急速增加并且在I_E/I_M最高值点达到最大量。     

含芘荧光化学敏感器及其与核苷磷酸盐的相互作用

设计合成3种含芘荧光化学敏感器--化合物(Ⅰ),(Ⅱ),(Ⅲ). 研究了芘丁酸,化合物(Ⅰ),(Ⅱ),(Ⅲ)等与腺嘌呤,5-腺苷单磷酸二钠盐(AMP),5-腺苷二磷酸二钠盐(ADP),5-腺苷三磷酸四钠盐(ATP),5-脱氧胸腺嘧啶三磷酸四钠盐(dTTP)等生物活性分子相互作用时的荧光猝灭光谱,运用Stern-Volmer猝灭等方程分别求出它们相互作用时的猝灭常数及稳定常数. 结合化合物荧光寿命的测定,对含芘荧光化学敏感器在不同波长激发下所得的荧光光谱以及基态下自由分子的CPK模型等对上述含芘荧光化学敏感器同核苷磷酸盐的作用机制进行了讨论.     

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。     

分子动力学模拟研究荧光分子芘在磺基甜菜碱胶束中的增溶

采用分子动力学模拟研究了荧光分子芘在磺基甜菜碱两性表面活性剂聚集体中的增溶现象．结果表明,芘分子自发地自溶液中增溶进入胶束疏水内核的栅栏层区域．当胶束溶液中芘分子的局部浓度增大时,两个芘分子可以同时增溶进胶束的栅栏层区域,此时两个芘分子形成π-π共轭堆积的激发态络合物．但是由于荧光分子之间的弱兀．兀相互作用,激发态络合物在胶束中是不稳定的,表现为两个芘分子的多次结合和分离．模拟表明,分子动力学方法可以在分子水平上研究荧光探针分子在表面活性剂胶束中的增溶位点,解释荧光分子在胶束中的动力学现象．     

具有扭曲的分子内电荷转移的芳香酮衍生物的结构与光谱性能研究

设计合成了一系列基于芳香酮的具有分子内扭曲态电荷转移(TICT)特性的化合物,通过线性光物理性质与双光子吸收性质的表征,研究了分子结构中不同共轭基团和不同取代基位置对化合物光谱性能的影响,同时通过溶剂效应研究了化合物的分子内电荷转移性质。结合理论计算结果表明分子的共轭骨架和取代基的位置都能显著影响分子内电荷转移特征。其中芴酮系列的化合物表现出了较强的双光子吸收与聚集诱导荧光增强效应,在生物荧光成像领域有着潜在的应用价值。     

一种基于二芘基苯的高效有机固态蓝色荧光化合物

利用Suzuki偶联反应,合成了一种新的二芘基苯的衍生物2,5-二甲基-1,4-双(7-特丁基-1-)芘基苯,并研究了其吸收和发光性质随着溶剂和温度等条件的变化情况.实验表明,与不含特丁基的类似化合物相比,引入特丁基可以明显减弱分子间作用并避免激基缔合物的形成,因而在保持吸收和发射光谱的谱形及峰位基本不变的同时显著地增强了荧光发光效率.该化合物的固态荧光量子效率高达0.82.     

Twisted Intramolecular Charge Transfer in Polydimethylsilylene Bearing Pyrenyl Groups

Polydimethylsilylenes bearing pyrenyl groups exhibit emissions fromtwisted intramolecular charge transfer state between the aromatic ring and thesilicon backbone both in polar and nonpolar solvents.     

'Remote' adiabatic photoinduced deprotonation and aggregate formation of amphiphilic N-alkyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride salts

The absorption and emission properties of a series of amphiphilic N-alkyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride salts were investigated in solvents of different polarities and over a wide concentration range. For example, at 10(-5) M concentrations in tetrahydrofuran (THF), salts with at least one N-H bond exhibited broad, structureless emissions even though time-correlated single photon counting (TCSPC) experiments indicated negligible static or dynamic intermolecular interactions. Salts with a butylene spacer or lacking an N-H bond showed no discernible structureless emission; their emission spectra were dominated by the normal monomeric fluorescence of a pyrenyl group and the TCSPC histograms could be interpreted on the basis of intramolecular photophysics. The broad, structureless emission is attributed to an unprecedented, rapid, adiabatic proton-transfer to the medium, followed by the formation of an intramolecular exciplex consisting of amine and pyrenyl groups. The proposed mechanism involves excitation of a ground-state conformer of the salts in which the ammonium group sits over the pyrenyl ring due to electrostatic stabilization. At higher concentrations, with longer N-alkyl groups, or in selected solvents, electronic excitation of the salts led to dynamic and static excimeric emissions. For example, whereas the emission spectrum of 10(-3) M N-hexyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride in THF consisted of comparable amounts of monomeric and excimeric emission, the emission from 10(-5) M N-dodecyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride in 1:9 (v:v) ethanol/water solutions was dominated by excimeric emission, and discrete particles near micrometer size were discernible from confocal microscopy and dynamic light scattering experiments. Comparison of the static and dynamic emission characteristics of the particles and of the neat solid of N-dodecyl-N-methyl-3-(pyren-1-yl)propan-1-ammonium chloride indicate that molecular packing in the microparticles and in the single crystal are very similar if not the same. It is suggested that other examples of the adiabatic proton transfer found in the dilute concentration regime with the pyrenyl salts may be occurring in very different systems, such as in proteins where conformational constraints hold ammonium groups over aromatic rings of peptide units.     

Spectroscopic and computational studies of a Ru(II) terpyridine complex: the importance of weak intermolecular forces to photophysical properties

The complex [Ru(tpy)(CO)(2)TFA]+[PF(6)]- (where tpy = 2,2':6',2' '-terpyridine and TFA = CF(3)CO(2)-) (1) has been synthesized and fully characterized spectroscopically. The X-ray structure of the complex has been determined. The photopysical properties of the ruthenium complex and the free ligand tpy have been investigated at room temperature and at 77 K in acetonitrile solution and in the solid state. Their electronic spectra are highly influenced by intermolecular stacking interactions, both in solution and in the solid state. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed to characterize the electronic structure and the excited states of [Ru(tpy)(CO)(2)TFA]+[PF(6)]- and tpy. TDDFT calculations on three different conformations of free ligand have been performed as well. Absorption and emission spectra of tpy have been studied at different temperatures and concentrations in order to have a better understanding of this ruthenium derivative's properties. The absorption spectrum of 1 is characterized by metal-perturbed ligand-centered (LC) bands in the UV region. No metal-to-ligand charge transfer (MLCT) bands are observed in the visible for the complex. Only at high concentrations (10(-4) M) does a very weak band appear at 470 nm. At 77 K and low concentrations, solutions of 1 exhibit a major 3LC emission band centered at 468 nm (21.4 x 10(-3) cm(-1)). When the concentration of the complex is increased, an unstructured narrow emission at 603 nm (16.6 x 10(-3) cm(-1)), with a lifetime of 10 micros, dominates the emission spectrum in glassy acetonitrile. This emission originates from a pi-pi stacked dimeric (or oligomeric) species. TDDFT calculations performed on a tail-to-tail dimer structure, similar to that seen in the solid state, ascribe the transition to a triplet excited state, where intermolecular metal (d) --> ligand (pi*, polypyridine) charge transfer occurs. A good estimate of the transition energy is also obtained (623 nm, 1.94 eV).     

Characterization of the molecular parameters determining charge transport in anthradithiophene

The molecular parameters that govern charge transport in anthradithiophene (ADT) are studied by a joint experimental/theoretical approach involving high-resolution gas-phase photoelectron spectroscopy and quantum-mechanical methods. The hole reorganization energy of ADT has been determined by an analysis of the vibrational structure of the lowest ionization band in the gas-phase photoelectron spectrum as well as by density-functional theory calculations. In addition, various dimers and clusters of ADT molecules have been considered in order to understand the effect of molecular packing on the hole and electron intermolecular transfer integrals. The results indicate that the intrinsic electronic structure, the relevant intramolecular vibrational modes, and the intermolecular interactions in ADT are very similar to those in pentacene.     

Intramolecular charge transfer in 1:1 Cu(II)/pyrenylcyclam dendrimer complexes

Two newly synthesized pyrenylcyclam dendrons (1 and 2) exhibit a new emission band centered at 450 nm when coordinated with copper triflate. Observed fluorescence shifts induced by coordinative metalation indicate an unusual intramolecular charge transfer from a pyrenyl excited state to the coordinated metal ion that competes with pyrene excimer formation. This interaction likely proceeds by photoexcitation of pi-complex of the appended arene, followed by intramolecular charge transfer within the dendritic 1:1 cyclam/metal complex, effecting reduction of the bound Cu(II) metal ion. The appended dendritic groups not only decrease the equilibrium binding constant with Cu(II) but also participate in a new excited-state pathway as an alternative to energy-dissipative excimer formation.     

Structural and electronic properties of the charge-transfer complex H3P...Br2 determined by Fourier transform microwave spectroscopy

The ground-state rotational spectra of six isotopomers of the symmetric-top complex H3P...Br2 have been measured by the technique of pulsed-nozzle, Fourier transform microwave spectroscopy. The spectroscopic constants B0, DJ, DJK, chiaa(Brx) and Mbb(Brx), x=i (inner) or o (outer) bromine atom, were obtained from analysis of the spectra. Interpretation of these constants with the aid of models revealed that the pre-reactive complex has an intermolecular bond of length r(P...Br) = 3.0440(4) A between the P atom of PH3 and one Br atom of Br2 and that this bond is a relatively strong one, as measured by the intermolecular stretching force constant ksigma-9.8 Nm(-1). The complex was discovered to have a significant contribution from charge transfer in the ground state by establishing the fraction of intermolecular charge transferred from P to Bri[sigmai = 0.077(23)] and the fraction of intramolecular charge transferred from Bri to Bro [sigmap(Br)=0.11(1)].     

Solvent switching of intramolecular energy transfer in bichromophoric systems: photophysics of (2,2'-bipyridine)tetracyanoruthenate(II)/pyrenyl complexes

The supramolecular systems [Ru(Pyr(n)bpy)(CN)(4)](2-) (n = 1, 2), where one and two pyrenyl units are linked via two-methylene bridges to the [Ru(bpy)(CN)(4)](2-) chromophore, have been synthesized. The photophysical properties of these systems, which contain a highly solvatochromic metal complex moiety, have been investigated in water, methanol, and acetonitrile. In all solvents, prompt and efficient singlet-singlet energy transfer takes places from the pyrene to the inorganic moiety. Energy transfer at the triplet level, on the other hand, is dramatically solvent dependent. In water, the metal-to-ligand charge transfer (MLCT) emission of the Ru-based chromophore is completely quenched, and rapid (200 ps for n = 1) irreversible triplet energy transfer to the pyrene units is detected in ultrafast spectroscopy. In acetonitrile, the MLCT emission is practically unaffected by the presence of the pyrenyl chromophore, implying the absence of any intercomponent triplet energy transfer. In methanol, triplet energy transfer leads to an equilibrium between the excited chromophores, with considerable elongation of the MLCT lifetime. The investigation of the [Ru(Pyr(n)bpy)(CN)(4)](2-) systems in methanol provided a very detailed and self-consistent picture: (i) The initially formed MLCT state relaxes toward equilibrium in 0.5-1.3 ns (n = 1, 2), as monitored both by ultrafast transient absorption and by time-correlated single photon counting. (ii) The two excited chromophores decay with a common lifetime of 260-450 ns (n = 1, 2), as determined from the decay of MLCT emission (slow component) and of the pyrene triplet absorption. (iii) These equilibrium lifetimes are fully consistent with the excited-state partition of 12-6% MLCT (n = 1-2), independently measured from preexponential factors of the emission decay. Altogether, the results demonstrate how site-specific solvent effects can be used to control the direction of intercomponent energy flow in bichromophoric systems.     

Substituent effects on the electronic characteristics of pentacene derivatives for organic electronic devices: dioxolane-substituted pentacene derivatives with triisopropylsilylethynyl functional groups

The intramolecular electronic structures and intermolecular electronic interactions of 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene), 6,14-bis-(triisopropylsilylethynyl)-1,3,9,11-tetraoxa-dicyclopenta[b,m]-pentacene (TP-5 pentacene), and 2,2,10,10-tetraethyl-6,14-bis-(triisopropylsilylethynyl)-1,3,9,11-tetraoxa-dicyclopenta[b,m]pentacene (EtTP-5 pentacene) have been investigated by the combination of gas-phase and solid-phase photoelectron spectroscopy measurements. Further insight has been provided by electrochemical measurements in solution, and the principles that emerge are supported by electronic structure calculations. The measurements show that the energies of electron transfer such as the reorganization energies, ionization energies, charge-injection barriers, polarization energies, and HOMO-LUMO energy gaps are strongly dependent on the particular functionalization of the pentacene core. The ionization energy trends as a function of the substitution observed for molecules in the gas phase are not reproduced in measurements of the molecules in the condensed phase due to polarization effects in the solid. The electronic behavior of these materials is impacted less by the direct substituent electronic effects on the individual molecules than by the indirect consequences of substituent effects on the intermolecular interactions. The ionization energies as a function of film thickness give information on the relative electrical conductivity of the films, and all three molecules show different material behavior. The stronger intermolecular interactions in TP-5 pentacene films lead to better charge transfer properties versus those in TIPS pentacene films, and EtTP-5 pentacene films have very weak intermolecular interactions and the poorest charge transfer properties of these molecules.