卟啉-酞菁分子内能量传递和电子转移的溶剂效应

用稳态荧光光谱研究了以氧原子和哌嗪作为连接基的卟啉酞菁二元分子在不同溶剂中的分子内能量传递和电子转移过程结果表明;分子内的能量传递和电子转移是两个相互竞争的过程，在非极性溶剂中，激发单重态的能量传递是主要过程，而在极性溶剂中则以电子转移为主运用Rehm-Weller公式计算了两种二元化合物在不同溶剂中的电子转移反应的自由能变化△G0ET，表明溶剂的极性对电子转移反应的自由能变化△G0ET影响很大极性越大;体系中的电子转移反应的△G0ET、越负，电子转移反应越易进行由于电子转移过程较能量传递过程进行得快，所以表现为体系中能量传递效率降低而电子转移效率增大。两种二元化合物的能量传递效率（φEnT）利和电子转移效率（φET）随溶剂的极性的变化具有相同的变化趋势     

以共价键相连的卟啉-酞菁化合物分子内能量传递及光诱导电子转移

合成了叶啉与酞菁以共价键连接起来的双发色团分子。测定了它们的吸收光谱,荧光光谱,荧光寿命等。计算了分子内能量传递过程的效率(φ_EnT)及速率常数(κ_EnT)。结果表明:在稀溶液中,卟啉与酞菁等克分子混合时,观察不到分子间能量传递过程现象的发生;而双发色团分子的分子内能量传递过程则明显发生了,其效率(φ_EnT=13～70%)与速率常数(κ_EnT=1.2×10⁷～2.0×10⁸s^-1)取决于分子的结构类型。电子转移与能量传递过程与介质性质有关。在极性溶剂中有利于电子转移过程的进行,而不利于能量传递过程;在非极性溶剂中,则有利于能量传递过程的进行,而不利于电子转移。 选择性激发酞菁发色团,观测到了只有电子转移发生的过程,其电子转移效率达到38%。     

曙红与卟啉分子间和分子内的光致相互作用

合成了以半刚性链(一CH_2phCH_2—)和柔性链(—(CH_2)_4—)连接的曙红-卟啉二元化合物及其模型化合物.通过吸收光谱、荧光光谱、激发光谱及荧光寿命研究了模型化合物分子间的相互作用和二元化合物分子内的光致电子转移和能量传递.结果表明:二元化合物的模型化合物曙红乙酯和卟啉易形成基态复合物 在二元化合物分子内激发曙红时,曙红能将其单重态能量传递给卟啉,并能引发分子内的电子转移;激发卟啉时,能发生曙红向卟啉的电子转移.分析了分子构型和溶剂极性对2种过程的影响.     

正丁醇在N,N-二甲基甲酰胺+水溶液中的体积性质

测定了２９８。１５Ｋ时正丁醇＋Ｎ，Ｎ－二甲诺甲酰胺（ＤＭＦ）＋水三元系的密度求出正丁醇在ＤＭＦ＋水混合溶剂中的表观摩尔体积。观察２到：⑴Φ＾０．Ｅ～ｆｍ与ＶＤＭＦ＾Ｅ～ｆｍ之间存在相似变化关系，其中Φ２＾０．Ｅ为正丁醇的过量无限稀释表观摩尔体积，ＶＥＭＦ＾Ｅ为ＤＭＦ＋水二元系中ＤＭＦ的过量偏摩尔体积，ｆｍ为混合溶剂中ＤＭＦ的摩尔分数。⑵Ｂ１～ｆｍ与０６２１２＾０．Ｅ～ｆｍ之间存的反向变化关系。Ｂ１     

树枝形聚合物修饰双8-羟基喹啉衍生物的合成及稳态光物理性质研究

设计合成了1 3代芳醚骨架树枝形聚合物修饰的双8 羟基喹啉衍生物.对这些化合物在不同溶剂中的荧光光谱研究表明,随着代数的增加,目标树枝形聚合物的荧光量子产率增大,树枝形聚合物对核心发色团具有一定的隔离作用,并且目标分子内可以发生从骨架向核心发色团的能量传递.     

噻吩甲酰三氟丙酮和4,5-二氮芴-9-酮及4,5-二氮芴-9-酮连氮铕(Ⅲ)三元配合物的合成和表征

合成了Ｅｕ（ＴＴＡ）３Ｌ１（Ⅰ）和［Ｅｕ（ＴＴＡ）３］２Ｌ２（Ⅱ）二种新的铕（Ⅲ）三元配合物（ＴＴＡ＝噻吩甲酰三氟丙酮一价阴离子、Ｌ１＝４，５－二氮芴－９－酮、Ｌ２＝４，５－二氮芴－９－酮连氮）。用元素分析、ＩＲ、ＵＶ和溶液荧光光谱对配合物进行了表征。探讨了溶剂对Ｅｕ（Ⅲ）三元配合物荧光光谱的影响，发现在ＣＨ３ＣＮ中Ｅｕ（Ⅲ）三元配合物发光效果最好，而溶剂ＤＭＦ会使配合物荧光减弱     

1,3-二β-萘甲酰基杯[4]芳烃的荧光光谱与光二聚反应

本文合成了含荧光发色团的杯芳烃衍生物1,3-二β-萘甲基杯[4]芳烃1,研究了它在极性溶剂及非极性溶剂中的光物理与光化学行为,并通过萘发色团荧光及光二聚反应研究了杯[4]芳烃衍生物的构象。     

以聚醚链相连的萘甲酸酯-氨基吖啶体系的合成及分子内能量传递研究

本文分别用聚三乙二醇及聚四乙二醇柔性链将α-萘甲酸与9-氨基吖啶连接起来,合成了新型二元发色团分子体系,发现在两个体系中,选择性激发α-萘甲酸酯,都可以发生从α-萘甲酸酯到9-氨基吖啶的高效率的单重态-单重态能量转移,并讨论了溶剂极性对能量传递效率的影响。     

高Tg可溶含偶氮三嗪染料基团的侧链型共聚聚酰亚胺的合成与表征

采用两步法合成了两个系列侧链含新型侧氮三嗪染料发色团的共聚聚酰亚胺ＯＰＩ（ｘ）和ＰＰＩ（ｘ）。用红外光谱,紫外－可见光谱ＤＳＣ和ＴＧＡ等手段对其进行表征,它们均溶于强极性非质子溶剂,如ＮＭＰ,ＤＭＡｃ,ＤＭＦ,ＤＭＳＯ和１,４－丁内酯等。其截止吸收波长小于５００ｎｍ,在大于５００ｎｍ,波长范围内基本透明,这些共聚物的特性粘数在０．２５－０．５０ｄＬ／范围内,它们都表现出较高的玻璃化转变温度（Ｔｇ）,以刚性相对较大的均苯四甲酸二酐（ＰＭＤＡ）为二酐单体的ＰＰＩ（ｘ）的Ｔｇ在５７３Ｋ左右;以二苯醚－３,３′,４,４′－四甲酸二酐（ＯＰＤＡ）为单体的ＯＰＩ（ｘ）的Ｔｇ在５３３－５４３Ｋ之间,具基本与染料发色团含量无关,所有的共聚聚酰亚胺都表现出优良的的高温稳定性,其５％热失重温度比相应聚合物Ｔｇ高１００Ｋ以上。     

多变鱼腥藻中藻红蓝蛋白内能量传递机制的研究

通过利用稳态光谱技术,光谱解叠技术和时间分辨荧光光谱技术对PEC单体内的能量传递过程进行详细研究.结果表明:在PEC单体内.α亚基上的PVB发色团可以将激发能传递给β亚基上的2个PCB发色团上;其能量传递时间常数分别为34.7和130ps;1.57us的组分归属为β亚基上PCB发色团终端发射;515ps的组分可初步指认为β亚基上两个PCB发色团间的能量传递时间常数.     

Synthesis and photophysical properties of porphyrin-phthalocyanine heterodimer linked by piperazine

A porphyrin-phthalocyanine heterodimer linked by piperazine has been synthesized and characterized by spectroscopic methods.UV-visible absorption spectra indicated the presence of weak intramolecular interaction between the two chromophores.Selective excitation of the porphyrin moiety leads to energy transfer process to the phthalocyanine subunit.Furthermore,on the bases of the solvent-dependent fluorescence data,a competing electron transfer reaction is shown to occur in this heterodimer.The efficiency of both photophysical processes depends strongly on solvent polarity and is related to the separation distance of the two chromophores and their relative orientation.The value of △GET0 obtained using the Rehm-Weller equation clearly indicates that the heterodimer exists preferably in the "boat form" upon excitation in good agreement with the experimental results of co-occurence of energy and electron transfer process observed for the heterodimer.     

Photoinduced intermolecular and intramolecular actions between eosin and porphyrin

Two dyads of eosin and porphyrin linked with a semi-rigid (-CH2phCH2-) or flexible (-(CH2)4-) bridge and their reference model compounds were synthesized and characterized The intermoleccular interaction and intramolecular photoinduced singlet energy transfer and electron transfer were studied by their absorp tion spectra,fluorescence emission,excitation spectra and fluorescence lifetime The model compounds,ethyl ester of eosm (EoEt) and porphyrin (PorEt),could form complexes in the ground state.When the eosin moieties in dyads were excited,they could transfer some singlet energy to the porphyrins; in the meantime,they could also ndsce electron transfer between two chromophores.Exciting the porphyrin moieties in dyads could induce electron transfer from eosin moieties to porphyrin moieties.The efficiencies (EnT,ET) and rate constants (kEnT,kET) were related to the polarity of solvents and mutual orientation of the two chromophores in dyads.     

Porphyrin-fullerene linked systems as artificial photosynthetic mimics

We have prepared a variety of porphyrin-fullerene linked systems to mimic photoinduced energy and electron transfer (ET) processes in photosynthesis. Photodynamical studies on porphyrin and analogs-fullerene linked systems have revealed the acceleration of photoinduced electron transfer and charge-shift and the deceleration of charge recombination, which is reasonably explained by the small reorganization energies of electron transfer in fullerenes. In this context, we have proposed two strategies, photoinduced single-step and multi-step electron transfers, for prolonging the lifetime of a charge-separated state in donor-acceptor linked systems. The single-step ET strategy allowed a zinc chlorin-fullerene linked dyad to extend the lifetime up to 120 seconds in frozen PhCN at 123 K, which is the longest value of charge separation ever reported for donor-acceptor linked systems. Unfortunately, however, the quantum yield of formation of the charge-separated state was as low as 12%, probably due to the decay of the precursor exciplex state to the ground state rather than to the favorable complete charge-separated state. In contrast, the multi-step ET strategy has been successfully applied to porphyrin-fullerene linked triads, tetrads, and a pentad. In particular, a ferrocene-porphyrin trimer-fullerene pentad revealed formation of a long-lived charge-separated state (0.53 s in frozen DMF at 163 K) with an extremely high quantum yield (83%), which is comparable to natural bacterial reaction centers. These results not only provide valuable information for a better understanding of photoinduced energy and electron transfer processes in photosynthesis, but also open the door for the development of photoinitiated molecular devices and machines.     

Photoinduced electron transfer across linearly fused oligo-norbornyl structures

The rates of photoinduced electron transfer (ET) reactions across two oligo-norbornyl spacer groups (S), that is, structure 1 fused by two norbornadiene (NBD) units and structure 2 fused by three NBD units, are examined. Substituted naphthalene acted as an electron donor (D), whilst ethylene-1,2-dicarboxylate as an electron acceptor (A). ET rates were measured by fluorescence quenching experiments on these D-S-A dyads, and the results were correlated with reaction free energies according to the Marcus relationship. It was found that naphthalene with phenyl substituents showed relatively slower ET rates. The conformational flexibility of phenyl substituents may cause a hindrance on the electronic coupling between D and A. Another salient feature was the abnormally high quenching rates observed in nonpolar solvents such as cyclohexane, the results of which may be ascribed to a competing energy transfer process.     

Solvent effects on competitive intramolecular electron transfer and energy transfer in a covalently linked porphyrin-phthalocyanine heterodimer

Photophysical properties of a porphyrin-phthalocyanine heterodimer covalently linked with a dipentoxy chain have been studied.Absorption spectra show that there is weak exciton coupling between the two chromophores in the ground state.Fluorescence spectra show that intramolecular energy transfer from porphyrin to phthalocyanine moiety occurs in competition with electron transfer.The efficiency of these two processes depends upon the mutual orientation of the two chromophores.The effect of solvent polarity on the intramolecular processes is also discussed.     

磷酰化肽链中电子转移的ESR研究

当前生命科学正以前所未有的速度向前发展，从对核酸的深入研究开始过渡到对蛋白质结构与功能的注意，尤其是近年来基因调控研究的重大进展是发现非组蛋白具有高度的磷酸化的特性［1］，研究证明，核内蛋白磷酸化和去磷酸化则是基因表达调控的重要方式之一［2，3］，它是酶活性调节、基因表达调控、细胞转化恶变的关键环节；同时在解决肿瘤的发生和治疗、病毒的感染和诊治、辐射损伤、抗衰老等实际问题上有突出意义，如1992年Krebus和Fisher因为在蛋白的可逆磷酸化方面的突出贡献而获得诺贝尔生理和医学奖．而电子转移是一切化学变化的基础…     

Generation of phosphorescent triplet states via photoinduced electron transfer: energy and electron transfer dynamics in Pt porphyrin-Rhodamine B dyads

Control over generation and dynamics of excited electronic states is fundamental to their utilization in all areas of technology. We present the first example of multichromophoric systems in which emissive triplet states are generated via a pathway involving photoinduced electron transfer (ET), as opposed to local intrachromophoric processes. In model dyads, PtP-Ph(n)-pRhB(+) (1-3, n = 1-3), comprising platinum(II) meso-tetraarylporphyrin (PtP) and Rhodamine B piperazine derivative (pRhB(+)), linked by oligo-p-phenylene bridges (Ph(n)), upon selective excitation of pRhB(+) at a frequency below that of the lowest allowed transition of PtP, room-temperature T(1)→S(0) phosphorescence of PtP was observed. The pathway leading to the emissive PtP triplet state includes excitation of pRhB(+), ET with formation of the singlet radical pair, intersystem crossing within that pair, and subsequent radical recombination. Because of the close proximity of the triplet energy levels of PtP and pRhB(+), reversible triplet-triplet (TT) energy transfer between these states was observed in dyads 1 and 2. As a result, the phosphorescence of PtP was extended in time by the long decay of the pRhB(+) triplet. Observation of ET and TT in the same series of molecules enabled direct comparison of the distance attenuation factors β between these two closely related processes.     

Photoinduced intramolecular electron transfer between fluorescein and carbazole

Several dyads consisting of a fluoreseein covalently linked with a carhazole at site 2 or site 6 have been synthesized and characterized.Studies of absorption spectra,emission spectra and fluorescence lifetime quern hing Indicate that the ground-state interaction between fluorescein and carhazole in dyads is negligible and the intramolecular electron transfer (ET) reactions are mainly of dynamic process.Moreover,the efficiency and raie conslam of lectron transfer reactions in ZFO4 (carbazole linked at site 2'of fluorescein) are larg er than those in 4FOZ (carbazole linked at site 6 of fluorescein) 0 74; KET 11×108S-1),because the mutual orientation of donor and acceptor in ZFO4 is nearly face-to-face,which is more favorable to the process than the shoulder-to-shoulder mutual orientation in 4FOZ.Estimations are also formed of the free energy change of the photomduced electron transfer and the back reactions in the dyads.