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1.
利用荧光手段对自制的3种卟啉蒽醌化合物及其锌配合物与母体卟啉进行了研究,计算了各种化合物单重激发态的能量Es,荧光量子产率及荧光猝灭百分率。从荧光猝灭的角度证明了它们确实能在激发下进行分子内电子转移,形成分子内电荷分离态。同时探讨了有机碱的轴向配位及溶剂对PAQ化合物荧光性质的影响。  相似文献   

2.
用ESR研究了几种新型卟啉蒽醌化合物低温下光诱导产生分子内电子转移产物P^+·-AQ^-·自由基对。对比研究了不同卟啉配体、金属卟啉、有机碱轴向配位和溶剂对电子转移的影响。  相似文献   

3.
利用荧光手段对自制的3种卟啉蒽醌化合物及其锌配合物与母体卟啉进行了研究,计算了各种化合物单重激发态的能量Es、荧光量子产率及荧光猝灭百分率.从荧光猝灭的角度证明它们确实能在光激发下进行分子内电子转移,形成分子内电荷分离态.同时探讨了有机碱的轴向配位及溶剂对PAQ化合物荧光性质的影响.  相似文献   

4.
采用循环伏安(CV)法研究了卟啉蒽醌(PAQ)化合物的氧化还原性质,测定了氧化还原电势,求得了分子内电子传递过程的自由能改变量ΔG0,估算了电子传递速度常数,推测了PAQ的结构与电荷分离效果的关系.  相似文献   

5.
用ESR研究了几种新型叶啉蒽醌化合物低温下光诱导产生分子内电子转移产物P+-AQ-自由基对.对比研究了不同卟啉配体、金属卟啉、有机碱轴向配位和溶剂对电子转移的影响.  相似文献   

6.
本文用聚四乙二醇柔性链将9-氨基啶和不同取代基的苯甲酸酯连接起来,合成了一类新型二元分子体系。对各体系中9-氨基啶的电子转移荧光猝灭进行了研究,并根据稳态荧光猝灭计算了体系中的荧光猝灭效率和荧光猝灭速率常数。  相似文献   

7.
对1984年Miller和Closs设计的有机分子内电子转移反应体系的反应速率常数进行了直接理论计算研究,获得与实验值接近的结果,理论计算结果进一步证明了体系中反转区的存在.  相似文献   

8.
本文报道了系列二肽链键联的卟啉-蒽醌及其金属配合物的微波合成,化合物的结构分别经UV-Vis,IR,1H NMR及元素分析确证。探讨了化合物分子内电子转移性质(IETP),并讨论了结构对IETP的影响。  相似文献   

9.
合成了以荧光素为光敏剂的电子给体-受体二元化合物荧光素蒽醌甲酯(FL-AQ),用吸收光谱、荧光光谱、荧光寿命研究了该化合物在乙醇溶液中的光物理性质,并首次用纳秒级瞬态吸收光谱检测了此化合物分子内光诱导电子转移所形成的电荷分离态.在溶液中激发FL,电子可从FL有效地转移到AQ,其速率常数为3.95×109s-1,效率为95%.但由于电荷分离态寿命较短,瞬态吸收信号弱,若在此溶液中加入二氧化钛(TiO2)纳米胶体,使FL-AQ吸附在胶体上,电荷分离态信号明显增强.480nm处FL的寿命为11.1μs;560nm处AQ的寿命为8.93μs.  相似文献   

10.
N-(1-萘基)氨基乙酸的激发态分子内电荷转移和电子转移   总被引:1,自引:0,他引:1  
氨基酸是蛋白质的基本结构单位 ,水溶液中基态氨基酸分子以内盐形式存在 [1] .由于质子化氨基的正诱导效应 ,羧基的离解常数显著提高 ,如氨基乙酸的羧基离解常数 ( 4.57× 1 0 -3mol/L,2 5℃ [1] )是乙酸 ( 1 .74× 1 0 -5 mol/L[2 ] )的 2 63倍 ;同时内盐结构亦使氨基酸和肽链具有分子内电偶极 ,后者已在肽链上电荷转移过程的调控中发挥重要作用 [3,4] .激发态氨基酸或肽的诱导效应和电偶极性质的研究尚未见报道 ,其主要原因可能是难有合适的激发方式和研究方法 .然而相关研究应予重视 ,因为研究结果将可能为生物酶活性的调节提供一种新的…  相似文献   

11.
The condensation reaction of 2-cyanomethyl-5-nitropyridine with aromatic aldehydes has been carried out with the aim of preparing 2-azastilbene derivatives having intramolecular charge transfer. The yield of the condensation products can be increased if the reaction is carried out in the medium used for obtaining the starting 2-cyanomethyl-5-nitropyridine without separating or purifying it. The electronic absorption spectra of the compounds show a charge-transfer band, the energy of which increases and the intensity falls with lowering of the electron-donor properties of the substituent in the 4-position. Introduction of the heteroatom into the acceptor part when changing from the stilbene to the 2-azastilbene system is accompanied by a decrease in the energy and increase in the intensity of the charge-transfer electronic transition.  相似文献   

12.
非平面分子内电荷转移离子配合物的合成及其光物理性质   总被引:4,自引:0,他引:4  
N-乙烯基咔唑三羰基铬为模板化合物, 选用丙烯基阳离子取代其中一个羰基配体, 合成了一种新型非平面分子内电荷转移有机金属配合物. 通过元素分析、红外、核磁共振确定了配合物的组成和结构, 电子吸收和荧光光谱结果表明配合物的光物理行为可通过配体取代调控.运用双光束前向简并四波混频(DFWM)的方法, 测试了配合物及配体的三阶非线性效应, 同时探讨了金属配位和配体取代对其的影响.  相似文献   

13.
14.
A series of rod‐shaped and related three‐branched push–pull derivatives containing phosphane oxide or phosphane sulfide (PO or PS)—as an electron‐withdrawing group conjugated to electron‐donating groups, such as amino or ether groups, with a conjugated rod consisting of arylene–vinylene or arylene–ethynylene building blocks—were prepared. These compounds were efficiently synthesized by a Grignard reaction followed by Sonogashira coupling. Their photophysical properties including absorption, emission, time‐resolved fluorescence, and two‐photon absorption (TPA) were investigated with special attention to structure–property relationships. These fluorophores show high fluorescence quantum yields and solvent‐dependent experiments reveal that efficient intramolecular charge transfer occurs upon excitation, thereby leading to highly polar excited states, the polarity of which can be significantly enhanced by playing on the end groups and conjugated linker. Rod‐shaped and related three‐branched systems show similar fluorescence properties in agreement with excitation localization on one of the push–pull branches. By using stronger electron donors or replacing the arylene–ethynylene linkers with an arylene–vinylene one induces significant redshifts of both the low‐energy one‐photon absorption and TPA bands. Interestingly, a major enhancement in TPA responses is observed, whereas OPA intensities are only weakly affected. Similarly, phosphane oxide derivatives show similar OPA responses than the corresponding sulfides but their TPA responses are significantly larger. Finally, the electronic coupling between dipolar branches promoted by common PO or PS acceptor moieties induces either slight enhancement of the TPA responses or broadening of the TPA band in the near infrared (NIR) region. Such behavior markedly contrasts with triphenylamine‐core‐mediated coupling, which gives evidence for the different types of interactions between branches.  相似文献   

15.
The donor-acceptor compounds N,N'-dicyanobenzo[b]naphtho[2,3-e][1,4]dithiin-6,11-quinonediimine (9a) and N,N'-dicyanobenzo[b]naphtho[2,3-e][1,4]oxathiin-6,11-quinonediimine (10a) and their methyl-substituted derivatives (9b and 10b-d, respectively) have been prepared, and their structural and electronic properties have been characterized by both experimental techniques and quantum-chemical calculations. The (1)H-NMR spectra evidence the existence of a syn/anti isomerism in solution. Both experimental and theoretical data suggest that the preferred configuration of the N-CN groups corresponds to a syn isomer for 9 and to an anti isomer for 10. The X-ray analysis performed for 9b reveals that molecules are not planar and pack in vertical stacks showing an overlap between donor and acceptor moieties of adjacent molecules. In agreement with X-ray data, theoretical calculations predict that both for 9 and 10 the acceptor DCNQI moiety is folded and adopts a butterfly-type structure and the donor moiety is bent along the line passing through the heteroatoms. The energy difference between planar and butterfly structures is calculated to be < 3 kcal/mol at the ab initio 6-31G level. The UV-vis spectra present a broad absorption in the visible which corresponds to a photoinduced intramolecular electron transfer from the high-energy HOMO furnished by the donor moiety to the low-energy LUMO located on the DCNQI fragment. Cyclic voltammetry displays one oxidation peak to the cation and two one-electron reduction waves to the anion and dianion. Theoretical calculations show the planarization of the acceptor/donor moiety induced by reduction/oxidation. The formation of stable radical anions is corroborated by the intense EPR signals recorded for reduced 9. The assignment of the hyperfine coupling constants of the EPR spectra is consistent with the existence of a preferred syn configuration.  相似文献   

16.
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.  相似文献   

17.
本文采用时间相关单光子计数对卟啉酞菁TTP-(CH2)n-Pc模型化合物的光致电子转移进行了研究,发现激发Pc时,呈现单指数衰减,n=4时电子转移速率减小,活化能,重排能增加,电子转移效率下降,电子转移反应△GCS与电荷分离活化络合物衰变速率KCT,按以下规律:△G^(5)CS〉△^(3)CS〉△^(4)CS〉△^(2)CS,k^(2)CS〉k^(3)CS〉k^(4)CS〉k^(5)cs。其△G^  相似文献   

18.
设计并合成了以香豆素为荧光发色团的多氰基分子化合物TCC。分子内强烈的电荷转移效应使得其本身荧光较弱。巯基化合物如半胱氨酸(Cys)、高半胱氨酸(Hcy)和还原型谷胱甘肽(GSH)的加入能与TCC中的三氰基乙烯基进行加成反应从而破坏分子内电荷转移,使分子内电荷转移吸收峰消失,颜色由紫色变成黄绿色,最大吸收波长由560 nm移至380 nm。并且化合物的荧光也随着巯基化合物的加入逐渐增强,荧光的强度与巯基化合物的浓度有很好的线性关系,检测限可以达到10-5 mol/L。其它离子与不含巯基的氨基酸则不会与化合物TCC发生上述反应,也就不会对体系的吸收和荧光光谱产生明显的影响,从而实现高效、专一的识别巯基化合物。  相似文献   

19.
In the past two decades, perylenequinonoid derivatives (PQD), such as hypocrellin A (HA), hypocrellin B (HB) and hypericin (HYP) have attracted considerable attention owing to their excellent properties of photosensitization and great advantages over the investigation of intramolecular proton transfer (IPT)1-5. Previous researches demonstrated that IPT both in the ground state and excited states exists in PQD and is critical for PQD to reserve their photosensitive activity3,6. Altho…  相似文献   

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