期刊文献+
共找到99篇文章
< 1 2 5 >
每页显示 20 50 100
Inuence of Electron Donating Ability on Reverse Intersystem Crossing Rate for One Kind of Thermally Activated Delayed Fluorescence Molecules
1
作者 Ming-lang Wang Jian-zhong Fan Li-li Lin 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2018年第3期291-299,367,共10页
First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF) molecules on their geometrical structures an... First-principles calculations are applied for investigating influence of electron donating ability of donor groups in eight thermally activated delayed fluorescence(TADF) molecules on their geometrical structures and transition properties as well as reverse intersystem crossing(RISC) processes. Results show that the diphenylamine substitution in the donor part can slightly change the bond angle but decrease bond length between donor and acceptor unit except for the lowest triplet state(Ti) of carbazole-xanthone molecule. As the electron donating ability of donor groups is increased, the overlap between the highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) is decreased. As the diphenylamine groups are added in donor part, the delocalization of HOMO is enlarged,which brings a decreased energy gap(△ES1-T1) between the lowest singlet excited state(S1)and T1 state. Furthermore, with the calculated spin-orbit coupling coefficient(HSO), one finds that the larger value of ■ is, the faster the RISC is. The results show that all investigated molecules are promising candidates as TADF molecules. Overall, a wise molecular design strategy for TADF molecules,in which a small △ES1-T1 can be achieved by enlarging the delocalization of frontier molecular orbitals with large separation between HOMO and LUMO, is proposed. 展开更多
关键词 Thermally ACTIVATED DELAYED fluorescence Donating ABILITY REVERSE intersystem crossing SPIN-ORBIT coupling
下载PDF
New insight into the ultra-long lifetime of excitons in organic-inorganic perovskite: Reverse intersystem crossing
2
作者 Guanghao Meng Yantao Shi +4 位作者 Xiangyuan Wang Wei Wang Shufeng Wang Min Ji Ce Hao 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2018年第5期1496-1500,共5页
Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the orig... Recently, an effective exciton diffusion length L exceeding 100μm has been reported for organic- inorganic halide perovskites owing to both the high mobility and ultra-long lifetime of the excitons; however, the origin of ultra-long L is still unclear in nature. In some photoelectric materials, reverse intersystem crossing (RISC) from the triplet to the singlet state can enhance the quantum yield of pho- toluminescence greatly. In this study, our theoretical investigation indicated that the energy difference △E_st between the singlet state and the triplet state of CH_3NH_3Pbl_3 was less than 0.1 eV, which represents one crucial prerequisite for the occurrence of RISC. Meanwhile, the experimental results showed that the photoluminescence lifetime increased with the increasing temperature, a typical feature of RISC. Based on this study, we put forward the hypothesis that the ultra-long lifetime of excitons in organic-inorganic halide perovskite might be caused by the RISC process. This may provide a new insight into the important photophysical properties of such novel photovoltaic materials. 展开更多
关键词 Inorganic-organic halide perovskite PHOTOPHYSICS Photoluminescence Reverse intersystem crossing Ultra-long lifetime
下载PDF
Efficient and Fast X-Ray Luminescence in Organic Phosphors Through High-Level Triplet-Singlet Reverse Intersystem Crossing 被引量:1
3
作者 Yang Zhang Minghong Chen +9 位作者 Xiaoze Wang Miao Lin Hongyu Wang Weihong Li Fuhai Chen Qing Liao Hongming Chen Qiushui Chen Meijin Lin Huanghao Yang 《CCS Chemistry》 CSCD 2024年第2期334-341,共8页
Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbid... Organic scintillators that efficiently generate bright triplet excitons are of critical importance for highperformance X-ray-excited luminescence in radiation detection.However,the nature of triplet-singlet spinforbidden transitions in these materials often result in long-lived phosphorescence,which is undesirable for ultrafast X-ray detection and imaging.Here we demonstrate that the effect of hybridized local and charge-transfer(HLCT)excited states enables organic scintillators to exhibit highly efficient and fast radioluminescence(RL)in response to X-ray irradiation.Our experimental and theoretical investigation shows that the oxidized 1,8-naphthalimide-phenothiazine dyad(OMNI-PTZ 2)with HLCT-excited states has an enhanced overlap integral of the highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)on MNIπ-orbitals,and moderate donor–acceptor electron interactions.As a result,the RL of these crystals exhibits a 61-fold increase and its monoexponential decay lifetime is three orders of magnitude faster compared to its corresponding thermally activated delayed fluorescence(TADF)molecule MNI-PTZ 1.We further demonstrate the practical utility of the OMNI-PTZ 2(G)in high-performance X-ray detection and imaging,achieving an X-ray dose sensitivity of 97 nGy s−1 and an exceptional spatial resolution of 20 lp/mm.Our study provides a promising molecular design principle for utilizing triplet excitons to develop high-efficiency and fast X-ray scintillators for the development of next-generation flexible and stretchable X-ray imaging detectors. 展开更多
关键词 organic scintillators X-ray imaging hybridized local and charge transfer excited state triplet-singlet reverse intersystem crossing high exciton utilization
原文传递
卤代姜黄素衍生物的合成及其对副溶血性弧菌的光动力灭活作用
4
作者 李雨薇 赵淑怡 +3 位作者 洪高博 张宾 焦龙 张晓晔 《食品科学》 EI CAS CSCD 北大核心 2024年第16期19-24,共6页
为提升姜黄素(curcumin,Cur)的光动力灭活(photodynamic inactivation,PDI)效果,合成新型卤代姜黄素衍生物(X-cur,X=F、Cl、Br)。通过测定X-cur的紫外-可见吸收光谱和荧光光谱,对比X-cur的单线态氧(^(1)O_(2))生成能力并辅助激发态理论... 为提升姜黄素(curcumin,Cur)的光动力灭活(photodynamic inactivation,PDI)效果,合成新型卤代姜黄素衍生物(X-cur,X=F、Cl、Br)。通过测定X-cur的紫外-可见吸收光谱和荧光光谱,对比X-cur的单线态氧(^(1)O_(2))生成能力并辅助激发态理论计算结果,分析筛选出具有PDI潜力的姜黄素衍生物。结果表明:随着非金属重原子卤素相对分子质量的增加,其自旋耦合作用逐渐增强,导致Br-cur具有最小的单重激发态(S_(1))和三重激发态(T_(3))能级差ΔE_(st(S1-T3))(0.140 eV)和最大的自旋轨道耦合值(0.642262 cm^(-1)),说明Br-cur最容易发生系间窜越过程进入到T_(3);此外,Br-cur相比于Cur和其他卤代姜黄素具有最小的S_(1)和基态(S_(0))间能级差(3.260 eV);以上两因素导致Br-cur极易被光激发且具有最高的^(1)O_(2)生成能力;在对水产品中典型食源性致病菌副溶血性弧菌(Vibrio parahaemolyticus)的PDI实验中,Br-cur的PDI作用依赖于其使用浓度和光照时间,且PDI效果显著高于Cur对照组,是极具应用潜力的新型PDI光敏剂。 展开更多
关键词 卤代姜黄素 光动力灭活 重原子效应 系间窜越 副溶血性弧菌
下载PDF
Factors affecting improvement of fluorescence intensity of quartet and doublet state of NO diatomic molecule excited by glow discharge
5
作者 Ahmed Asaad I Khalilt Reem A1-Tuwirqi +1 位作者 Mohamed Gondal Noura A1-Suliman 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第8期356-363,共8页
We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet (UV) to near infrared (NIR) in a low power glow discharge system. Th... We report on the observation of new fluorescence emission spectral transitions obtained from NO diatomic molecule in the region from ultraviolet (UV) to near infrared (NIR) in a low power glow discharge system. This glow discharge electronic excitation populates different quartet and doublet states of NO in its proximity such as the A2Z (/9 = 2), b4∑- (υ= 3), B2М (1) = 4), and X2Л (u= 33-32) states. Due to inter-system crossing, emission lines originating from these levels to lower lying states are recorded and spectral line assignments are performed. The observed systems include b4∑- a4∏, B21∏-a4∏, a4∏-X2I∏, A2∑X2∏, X2∏-X2∏ (33-15), X2∏-X2∏ (33-17), X2∏-X2∏ (33-20), and X2∏-X2∏ (33- 18). This new information will conduce to the better understanding of the interesting features of NO molecule. Such parameters that affect the recording of low density of NO molecules are also discussed In addition to the factors such as the time evolution, argon gas concentration relative to NO mixture, the percentage of NO molecular gas concentration, discharge electric current signals and discharge applied voltage are studied. Those factors would enhance the fluorescence signal intensity of NO molecules. The recent results might be significant as reference data for optimizing the glow discharge spectrometer and diagnostics of NO gas. 展开更多
关键词 fluorescence emission NO molecule quartet states intersystem crossing glow discharge
下载PDF
Crossed Molecular Beams and Theoretical Studies of the O(~3P)+1,2-Butadiene Reaction:Dominant Formation of Propene+CO and Ethylidene+Ketene Molecular Channels
6
作者 Adriana Caracciolo Gianmarco Vanuzzo +4 位作者 Nadia Balucani Domenico Stranges Silvia Tanteri Carlo Cavallotti Piergiorgio Casavecchia 《Chinese Journal of Chemical Physics》 SCIE CAS CSCD 2019年第1期113-122,I0002,共11页
Detailed understanding of the mechanism of the combustion relevant multichannel reactions of O(3P) with unsaturated hydrocarbons (UHs) requires the identification of all primary reaction products, the determination of... Detailed understanding of the mechanism of the combustion relevant multichannel reactions of O(3P) with unsaturated hydrocarbons (UHs) requires the identification of all primary reaction products, the determination of their branching ratios and assessment of intersystem crossing (ISC) between triplet and singlet potential energy surfaces (PESs). This can be best achieved combining crossed-molecular-beam (CMB) experiments with universal, soft ionization, mass-spectrometric detection and time-of-flight analysis to high-level ab initio electronic structure calculations of triplet/singlet PESs and RRKM/Master Equation computations of branching ratios (BRs) including ISC. This approach has been recently demonstrated to be successful for O(3P) reactions with the simplest UHs (alkynes, alkenes, dienes) containing two or three carbon atoms. Here, we extend the combined CMB/theoretical approach to the next member in the diene series containing four C atoms, namely 1,2-butadiene (methylallene) to explore how product distributions, branching ratios and ISC vary with increasing molecular complexity going from O(3P))+propadiene to O(3P)+1,2-butadiene. In particular, we focus on the most important, dominant molecular channels, those forming propene+CO (with branching ratio ∽0.5) and ethylidene+ketene (with branching ratio ∽0.15), that lead to chain termination, to be contrasted to radical forming channels (branching ratio ∽0.35) which lead to chain propagation in combustion systems. 展开更多
关键词 Reactive scattering crossed molecular beams O(3P) reaction dynamics O(3P)+diene reactions Soft electron ionization intersystem crossing Ab initio quantum chemistry
下载PDF
蓝光热激活延迟荧光分子设计策略概述
7
作者 陶伟 崔林松 《功能高分子学报》 CAS CSCD 北大核心 2023年第3期240-260,共21页
热激活延迟荧光(thermally activated delayed fluorescence,TADF)分子由于三重态上的激子可以通过反向系间窜越到单重态并辐射发出荧光,因此在有机发光二极管(organic light-emitting diode,OLED)中理论上可以实现100%的激子利用率。具... 热激活延迟荧光(thermally activated delayed fluorescence,TADF)分子由于三重态上的激子可以通过反向系间窜越到单重态并辐射发出荧光,因此在有机发光二极管(organic light-emitting diode,OLED)中理论上可以实现100%的激子利用率。具有TADF特性的发光材料融合了第一代荧光材料和第二代磷光材料的优点,不仅可以实现100%的内量子效率,还有助于降低器件的材料成本,被誉为第三代OLED发光材料,并成为突破高效稳定蓝光OLED瓶颈的潜在解决方案。本文从发光机理出发,系统阐述了高效稳定蓝光TADF分子的设计策略,包括高荧光量子产率、短延迟荧光寿命、窄发射光谱半峰宽、显著的水平分子取向和良好的光电稳定性等。本文旨在为高性能蓝光TADF分子的开发提供理论支持。最后,总结了当前蓝光TADF材料存在的问题,并对其未来的发展前景进行了展望。 展开更多
关键词 热激活延迟荧光 有机电致发光二极管 蓝光材料 分子设计 反向系间窜越
下载PDF
基于蒽核的高性能深蓝光“热激子”材料 被引量:1
8
作者 许雷 俞越 +3 位作者 潘玉钰 王博涵 应磊 马於光 《发光学报》 EI CAS CSCD 北大核心 2023年第7期1300-1307,共8页
蓝光OLED材料是电致发光领域的关键和难点。基于高能激发态转换的“热激子”材料表现出优异蓝光材料的潜能。本文通过调节给受体的推拉电子能力,以蒽为核心构筑单元、三苯基苯为弱给体、苯氰基为受体,设计合成了一种新型D-π-A结构分子T... 蓝光OLED材料是电致发光领域的关键和难点。基于高能激发态转换的“热激子”材料表现出优异蓝光材料的潜能。本文通过调节给受体的推拉电子能力,以蒽为核心构筑单元、三苯基苯为弱给体、苯氰基为受体,设计合成了一种新型D-π-A结构分子TACN。扭曲的三苯基苯提供了高度扭曲的分子构象,有效减弱了聚集态下的猝灭效应,因此TACN表现出高的荧光量子产率(聚集态下47%)。实验结果和理论分析表明,TACN具备“热激子”特征,其大的T_(2)-T_(1)能隙(1.45 eV)有效阻碍了从T_(2)到T_(1)的内转换(IC)过程,而小的T_(2)-S_(1)能差(0.18 eV,T_(2)>S_(1))有利于促进反向系间窜越(RISC)过程。基于TACN的非掺杂器件表现出深蓝色发射(λmax=444 nm),半峰宽(FWHM)为59 nm,色坐标为(0.17,0.13)。其最大外量子效率(EQEmax)为8.3%,相应的激子利用率(EUE)最高为88.7%。 展开更多
关键词 有机发光二极管 热激子 蓝光材料 反向系间窜越
下载PDF
Alq_(3)/HAT-CN叠层电致发光器件的激子调控机制探究
9
作者 李万娇 关云霞 +6 位作者 保希 王成 宋家一 徐爽 彭柯敖 陈丽佳 牛连斌 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第21期318-329,共12页
叠层有机电致发光器件(organic electroluminescent device,OLED)因寿命长和电流效率高等优点引起广泛关注.本文利用Alq_(3)/HAT-CN作为中间连接层制备了双发光单元叠层OLED,对其光电性能和激子调控机制探究.结果表明,在80 mA/cm^(2)电... 叠层有机电致发光器件(organic electroluminescent device,OLED)因寿命长和电流效率高等优点引起广泛关注.本文利用Alq_(3)/HAT-CN作为中间连接层制备了双发光单元叠层OLED,对其光电性能和激子调控机制探究.结果表明,在80 mA/cm^(2)电流密度下,叠层OLED的亮度(11189.86 cd/m^(2))和效率(13.85 cd/A)达到了单发光单元OLED(亮度和效率分别为4007.14 cd/m^(2)和5.00 cd/A)的2.7倍.在室温下,磁场诱导极化子对发生系间窜越(intersystem crossing,ISC),增加三重态激子(triplet exciton,T_(1))浓度,促进电荷散射,使磁电致发光(magneto-electroluminescence,MEL)低磁场快速增加和高磁场缓慢上升.当固定电流,Alq_(3)/HATCN器件中未复合的电荷较少,导致T_(1)与电荷湮灭(triplet-charge annihilation,TQA)减弱,致使MEL上升幅度最小.随电流增大,T_(1)浓度升高使TQA增强而ISC减弱.降低温度,电荷减弱,T_(1)浓度增大,使T_(1)湮灭(triplet-triplet annihilation,TTA)增强.因此,通过改变注入电流和温度可调控T_(1)的浓度,进而影响ISC,TQA和TTA的强弱,导致直接发光的单重态激子数量的增加,最终引起叠层OLED发光效率的提高.总之,本工作有助于深入理解小分子叠层OLED发光机制,对探明其光电性能提高的机理具有重要意义. 展开更多
关键词 叠层有机电致发光器件 中间连接层 系间窜越 三重态与电荷湮灭
下载PDF
氮杂环配体对卤化亚铜配合物发光机制影响的理论研究
10
作者 王妤婕 张干兵 钟欣欣 《化学研究》 CAS 2023年第3期231-238,共8页
为深入探讨卤化亚铜配合物的发光机制,运用密度泛函理论和含时密度泛函理论的计算方法研究了三个结构相似的溴化亚铜配合物(CuBr-py、CuBr-iq、CuBr-nap)。研究结果表明,CuBr-py和CuBr-nap,电子和空穴重叠程度小,导致其ΔE_(ST)较小;S_... 为深入探讨卤化亚铜配合物的发光机制,运用密度泛函理论和含时密度泛函理论的计算方法研究了三个结构相似的溴化亚铜配合物(CuBr-py、CuBr-iq、CuBr-nap)。研究结果表明,CuBr-py和CuBr-nap,电子和空穴重叠程度小,导致其ΔE_(ST)较小;S_(1)与T_(1)间的重组能较小,使其可快速地完成反系间窜越过程,实现热活化延迟荧光(TADF)。此外,与CuBr-nap相比,CuBr-py自旋轨道耦合作用强,其磷光速率也较大,因此其具有TADF和磷光双通道发光特性。而CuBr-iq中喹啉环的存在增大了电子和空穴的重叠程度,ΔE_(ST)增大;同时S_(1)与T_(1)间的重组能较大,T_(1)无法顺利通过RISC过程回到S_(1),导致其最终呈现出磷光特性。这些理论计算结果与实验现象一致,且揭示了N杂环配体结构对于卤化亚铜配合物发光机制的影响规律,为设计和合成稳定高效的发光材料提供了有价值的理论指导。 展开更多
关键词 氮杂环 卤化亚铜 热活化延迟荧光 磷光 系间窜越 反系间窜越
下载PDF
Theoretical investigation on the fluorescent sensing mechanism for recognizing formaldehyde: TDDFT calculation and excited-state nonadiabatic dynamics
11
作者 杨云帆 杨璐佳 +2 位作者 马凤才 李永庆 邱岳 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第5期674-681,共8页
Inspired by the activity-based sensing method, the hydrazine-modified naphthalene derivative(Naph1) was synthesized and used as a fluorescent probe to detect formaldehyde(FA) in living cells. Through the condensation ... Inspired by the activity-based sensing method, the hydrazine-modified naphthalene derivative(Naph1) was synthesized and used as a fluorescent probe to detect formaldehyde(FA) in living cells. Through the condensation reaction between the probe Naph1 and analyte FA, researchers observed a ~14 folds enhancement of fluorescent signal around 510 nm in an experiment, realizing the high selectivity and sensitivity detection of FA. However, a theoretical understanding of the sensing mechanism was not provided in the experimental work. Given this, the light-up fluorescent detecting mechanism was in-depth unveiled by performing the time-dependent density functional theory(TDDFT) and the complete active space self-consistent field(CASSCF) theoretical calculations on excited-state intramolecular proton transfer(ESIPT)and non-adiabatic excited-state dynamics simulation. The deactivation channel of S_1/T_2 intersystem crossing(ISC) was turned off to successfully recognize FA. Insight into the ESIPT-based fluorescent detecting mechanism indicated that ESIPT was essential to light-up fluorescent probes. This work would provide a new viewpoint to develop ESIPT-based fluorescent probes for detecting reactive carbon species in vivo or vitio. 展开更多
关键词 proton transfer twisting intramolecular charge transfer intersystem crossing fluorescent probe
下载PDF
激基复合物有机发光二极管中系间窜越和反向系间窜越过程的非单调电流依赖关系
12
作者 赵茜 陈敬 +4 位作者 彭腾 刘俊宏 汪波 陈晓莉 熊祖洪 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第16期229-237,共9页
激基复合物有机发光二极管(exciplex-based organic light-emitting diodes,EB-OLEDs)中自旋对态(spin-pair states)的系间窜越(intersystem crossing,ISC)和反向系间窜越(reverse ISC,RISC)是重要的自旋混合过程.它们通常展示正常的电... 激基复合物有机发光二极管(exciplex-based organic light-emitting diodes,EB-OLEDs)中自旋对态(spin-pair states)的系间窜越(intersystem crossing,ISC)和反向系间窜越(reverse ISC,RISC)是重要的自旋混合过程.它们通常展示正常的电流依赖关系,即随电流的增大而减弱.本文利用磁电致发光(magneto-electrolumine-scence,MEL)作为指纹式探测工具,在具有不同电荷平衡的EB-OLEDs中观察到多种电流依赖的ISC和RISC过程.它们有趣的表现为:随着器件注入电流增大,非平衡器件中电流依赖的MEL曲线呈现从正常ISC(1-25μA)向反常ISC(25-200μA)过程的转换,而平衡器件中电流依赖的MEL曲线则展示从正常ISC(1-5μA)→反常RISC(10-50μA)→正常RISC(50-150μA)→反常ISC(200-300μA)过程的转换.通过拟合和解析MEL曲线,发现非平衡和平衡器件中的ISC和RISC过程随着电流增大都先增强后减弱.这些丰富而有趣的转换可归因于增大电流时自旋对态增加的数量与其减短的寿命之间的竞争.此外,平衡器件中的RISC过程比非平衡器件中的更强,从而导致平衡器件的外量子效率比非平衡器件的更高.显然,本文不但加深了对EB-OLEDs中电流依赖的ISC和RISC过程的理解,还为设计制作高效率EB-OLEDs提供了清晰的器件物理思路. 展开更多
关键词 激基复合物 磁电致发光 系间窜越 反向系间窜越
下载PDF
Spin-orbit Coupling and Intersystem Crossing in 4H-Pyran-4-thione: CASSCF//TD-B3LYP Study 被引量:1
13
作者 吕玲玲 刘新文 +2 位作者 袁琨 王永成 汪汉卿 《Chinese Journal of Chemistry》 SCIE CAS CSCD 2007年第10期1461-1466,共6页
The intersystem crossing channels of gaseous 4H-pyran-4-thione were investigated using the CASSCF//TD-B3LYP methods and group theory. Using the effective one-electron spin-orbit Harniltonian, the strengths of spin-orb... The intersystem crossing channels of gaseous 4H-pyran-4-thione were investigated using the CASSCF//TD-B3LYP methods and group theory. Using the effective one-electron spin-orbit Harniltonian, the strengths of spin-orbit coupling were estimated, which plays an essential role in the spin transitions between different spin states. Calculated results show that phosphorescence and non-radiative decay via intersystem crossing to the So state are concurrent processes occurring at the T1 state. A rapid depletion of the S1 state via intersystem crossing to the T1 state can be mediated by the T2 state, if spin relaxation is fast within the triplet levels. Our calculated results are in close agreement with experimental observations. 展开更多
关键词 4H-pyran-4-thione spin-orbit coupling intersystem crossing PHOSPHORESCENCE
原文传递
Aggregation Turns BODIPY Fluorophores into Photosensitizers:Reversibly Switching Intersystem Crossing On and Off for Smart Photodynamic Therapy 被引量:2
14
作者 Yan-Fei Kang Wen-Kai Chen +5 位作者 Kun-Xu Teng Ling-Yun Wang Xiao-Cheng Xu Li-Ya Niu Ganglong Cui Qing-Zheng Yang 《CCS Chemistry》 CAS 2022年第11期3516-3528,共13页
We report for the first time a practical and simple supramolecular approach to turn fluorophores into photosensitizers(PSs).Using boron dipyrromethene(BODIPY)as a proof-of-concept,eight BODIPY derivatives manifest bri... We report for the first time a practical and simple supramolecular approach to turn fluorophores into photosensitizers(PSs).Using boron dipyrromethene(BODIPY)as a proof-of-concept,eight BODIPY derivatives manifest bright fluorescence and generate negligible singlet oxygen in solution.In contrast,aggregation fails to emit fluorescence and enhances singlet oxygen generation.Experimentally,these aggregates have excellent photodynamic therapy(PDT)performance,and one even exhibits much stronger photocytotoxicity than the commercialized PS Ce6 under identical conditions.Theoretical studies show that this property originated from significantly reduced energy gaps between relevant excited singlet and triplet states,leading to considerably improved intersystem-crossing efficiency.Importantly,a simple disaggregation recovers the original properties of the fluorophores.This reversible switching property between fluorophores and PSs assists the development of smart PDT systems,in which singlet oxygen generation in tumors can be controlled in an intelligent manner after PDT treatment.The present work provides a novel strategy to design heavy-atom-free PSs and may pave the way to the development of smart PDT systems. 展开更多
关键词 PHOTOSENSITIZER AGGREGATION BODIPY photodynamic therapy intersystem crossing
原文传递
激基复合物有机发光二极管中平衡载流子增强电荷转移态的反向系间窜越过程
15
作者 王辉耀 魏福贤 +4 位作者 吴雨廷 彭腾 刘俊宏 汪波 熊祖洪 《物理学报》 SCIE EI CAS CSCD 北大核心 2023年第17期311-319,共9页
电荷转移(charge transfer,CT^(1)和CT^(3))态的反向系间窜越(reverse inter-system crossing,RISC,CT^(1)←CT^(3))过程是提高激子利用率的有效途径,精准利用该过程对于制备高效率激基复合物型(exciplex-type)有机发光二极管(organic l... 电荷转移(charge transfer,CT^(1)和CT^(3))态的反向系间窜越(reverse inter-system crossing,RISC,CT^(1)←CT^(3))过程是提高激子利用率的有效途径,精准利用该过程对于制备高效率激基复合物型(exciplex-type)有机发光二极管(organic light-emitting diodes,OLEDs)具有重要科学价值和应用前景.基于m-MTDATA:Bphen的典型激基复合物由于其内部高的RISC速率而受到广泛关注.但到目前为止,在实验上仅从瞬态光致发光谱中推测存在该RISC过程,这不利于全面认识并运用该过程设计高性能的光电器件.本文通过精确调控发光层(x m-MTDATA:y Bphen,x,y为质量分数)中给体与受体的共混比例和流过器件的载流子密度,获得了载流子平衡与非平衡的激基复合物器件,采用特征磁电导(magneto-conductance,MC)响应曲线可视化了平衡激基复合物器件中CT态间的RISC过程,且相比于非平衡器件,该器件具有更高的电致发光效率.本工作不仅能加深对于激基复合物器件中给体/受体共混比例影响载流子平衡的理解,还为最优利用RISC过程制备高效率光电器件提供理论依据和实验基础. 展开更多
关键词 m-MTDATA:Bphen 激基复合物 给体/受体的共混比例 磁电导 反向系间窜越过程
下载PDF
A multi-dimensional microcanonical Monte Carlo study of S_0→T_1 intersystem crossing of isocyanic acid
16
作者 ZHANG Feng1,2,FANG WeiHai1,LUO Yi2 & LIU RuoZhuang1 1 College of Chemistry,Beijing Normal University,Beijing 100875,China 2 Theoretical Chemistry,School of Biotechnology,Royal Institute of Technology,S-10691 Stockholm,Sweden 《Science China Chemistry》 SCIE EI CAS 2009年第11期1885-1891,共7页
A general formula for the multi-dimensional Monte Carlo microcanonical nonadiabatic rate constant expressed in configuration space is applied to calculate the rate of intersystem crossing(ISC) between the ground(S0) a... A general formula for the multi-dimensional Monte Carlo microcanonical nonadiabatic rate constant expressed in configuration space is applied to calculate the rate of intersystem crossing(ISC) between the ground(S0) and first excited triplet(T1) states for isocyanic acid.One-,two-and three-dimensional potential energy surfaces are constructed by coupled-cluster single-double CCSD calculations,which are used for Monte Carlo sampling.The calculated S0→T1 ISC rate is in good agreement with experimental findings,which gives us a reason to believe that the multi-dimensional Monte Carlo microcanonical nonadiabatic rate theory is a very effective method for calculating nonadiabatic transition rate of a polyatomic molecule. 展开更多
关键词 MULTI-DIMENSIONAL MONTE Carlo MICROCANONICAL NONADIABATIC rate theory intersystem crossing isocyanic ACID NONADIABATIC transition
原文传递
Enhancing Intersystem Crossing by Intermolecular Dimer-Stacking of Cyanine as Photosensitizer for Cancer Therapy
17
作者 Haiqiao Huang Dandan Ma +8 位作者 Qiang Liu Daipeng Huang Xueze Zhao Qichao Yao Tao Xiong Saran Long Jianjun Du Jiangli Fan Xiaojun Peng 《CCS Chemistry》 CAS 2022年第11期3627-3636,共10页
Development of new photosensitizers(PSs)with high singlet oxygen quantumyield and minimal side effects is of great interest in photodynamic therapy(PDT).Herein,a facile strategy to significantly improve photosensitiza... Development of new photosensitizers(PSs)with high singlet oxygen quantumyield and minimal side effects is of great interest in photodynamic therapy(PDT).Herein,a facile strategy to significantly improve photosensitization has been demonstrated for the first time with two pentamethine dyes connected by a varying alkyl chain resulting in a series of cyanine dimers.The photophysical properties of the dimerswere studied with steady-state optical spectroscopies,a timecorrelated single photon counting technique,and laser flash photolysis spectrometry.X-ray crystallography confirmed that the molecular packing modes of Cy-Bu-D and Cy-He-D were dominated by H-aggregation.The H-aggregation by dimerization suppresses the radiative singlet decay,which helps to stabilize the highly efficient triplet excitation state.Moreover,the dimers show more intensewavelength absorption in the nearinfrared(ɛ1.5-2.0 times more than monomer Cy-H at 650 nm),better singlet oxygen quantum yield,and a longer triplet-state lifetime than monomer Cy-H,providing excellent performance as a triplet PS.In vivo experiments demonstrated that Cy-He-D successfully suppresses tumor growth after PDT treatment.This work is beneficial to the design of novel heavy atom free PSs for PDT-based theranostic systems. 展开更多
关键词 DIMER intersystem crossing photodynamic therapy PHOTOSENSITIZERS cancer
原文传递
利用磁致发光曲线研究Rubrene器件中激子分裂和湮没过程 被引量:8
18
作者 陈秋松 袁德 +6 位作者 贾伟尧 陈历相 邹越 向杰 陈颖冰 张巧明 熊祖洪 《物理学报》 SCIE EI CAS CSCD 北大核心 2015年第17期334-341,共8页
为了研究Rubrene分子中激发态的能量共振和分子间π-π共轭的特性对有机磁效应的影响,本文制备了基于不同浓度和厚度的Rubrene有机发光器件,并在不同温度下测量了器件的电致发光磁效应(magnetoelectroluminescence,MEL).实验发现,发光层... 为了研究Rubrene分子中激发态的能量共振和分子间π-π共轭的特性对有机磁效应的影响,本文制备了基于不同浓度和厚度的Rubrene有机发光器件,并在不同温度下测量了器件的电致发光磁效应(magnetoelectroluminescence,MEL).实验发现,发光层中Rubrene的厚度和浓度均可以对器件中的MEL产生较大的影响,室温下MEL的高场值随Rubrene层厚度的增加而增加,并在30 nm之后逐步趋于饱和;随着Rubrene分子的浓度和测量温度的降低,MEL高场增加的幅度逐渐减小,甚至在低温时出现高场下降.通过对实验曲线进行数值拟合,认为Rubrene分子之间形成的π-π共轭结构有助于双分子相互作用的发生,单重态激子分裂、三重态激子之间的湮没和单一三重态极化子对的系间窜越三种过程在器件中相互竞争导致了所得MEL的变化.本工作有助于加深对有机光电子器件内部机理的认识. 展开更多
关键词 单重态分裂 三重态湮没 系间窜越 电致发光磁效应
下载PDF
Au^+(~1S,~3D)与N_2O(~1∑^+)反应机理的理论研究 被引量:3
19
作者 吕玲玲 王永成 《物理化学学报》 SCIE CAS CSCD 北大核心 2006年第3期265-269,共5页
采用密度泛函B3LYP方法,O和N用6-311+G*基组,Au+用赝势基组(8s7p6d)/[6s5p3d],研究了Au+(~1S,~3D)离子和N2O(~1∑^+)分子的反应机理.报道了在基态单重态和激发三重态势能面上各反应物、中间体和过渡态的构型特征及能量.结果表明,两个主... 采用密度泛函B3LYP方法,O和N用6-311+G*基组,Au+用赝势基组(8s7p6d)/[6s5p3d],研究了Au+(~1S,~3D)离子和N2O(~1∑^+)分子的反应机理.报道了在基态单重态和激发三重态势能面上各反应物、中间体和过渡态的构型特征及能量.结果表明,两个主反应通道Au+(1S)+N_2O(~1∑^+)→1NA-Complex-1→1NA-TS1→1NA-Complex-2→1NA-Crossing→[3OAuNN]+和Au+(1S)+N2O(~1∑^+)→1NB-Complex→1NB-Crossing→[AuNN(1∑+)]++O(3P)都需经过反应交叉势能面,出现“系间窜越”.用内禀坐标单点计算垂直激发态的方法确定了势能面交叉点,并用含时密度泛函TD-B3LYP方法进一步探讨了自旋翻转机理. 展开更多
关键词 Au^+(1S 3D) N2O(^1∑^+) 密度泛函理论 反应机理 系间窜越
下载PDF
RN_3解离反应中交叉点构型及电子密度拓扑分析 被引量:1
20
作者 曾艳丽 张雪英 +1 位作者 孟令鹏 郑世钧 《河北师范大学学报(自然科学版)》 CAS 北大核心 2007年第6期775-779,共5页
采用CASSCF(10,8)/3-21G方法优化了CH3N3,CH3CH2N3,(CH3)2CHN3和(CH3)3CN3单重态和三重态解离过程中交叉点的几何构型.4个反应中的交叉点的几何构型参数比较接近.采用电子密度拓扑分析方法计算了交叉点的电子密度拓扑性质.研究发现:交... 采用CASSCF(10,8)/3-21G方法优化了CH3N3,CH3CH2N3,(CH3)2CHN3和(CH3)3CN3单重态和三重态解离过程中交叉点的几何构型.4个反应中的交叉点的几何构型参数比较接近.采用电子密度拓扑分析方法计算了交叉点的电子密度拓扑性质.研究发现:交叉点在单重态和三重态途径上N(2)N(3)键的特性变化较大,在三重态反应途径上N(2)N(3)键更容易断裂. 展开更多
关键词 交叉点 CASSCF 电子密度拓扑分析
下载PDF
上一页 1 2 5 下一页 到第
使用帮助 返回顶部