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101.
Yujie Dong Junjie Shen Weijun Li Ruiyang Zhao Yuyu Pan Qingbao Song Cheng Zhang 《Tetrahedron》2019,75(18):2670-2675
In this work, we report two isomers composed of 1-phenyl-1H-phenanthro[9,10-d]imidazole (PI), hydroxyl and tetraphenylethylene (TPE), abbreviated as m-PITPE and p-PITPE. It is found that they exhibit similar aggregation-induced emission (AIE) behavior but totally different excited-state intramolecular proton transfer (ESIPT) characteristic, as a result of the different linkage sites of PI on TPE moiety. Theoretical calculations and their different experimental responses to F? demonstrate that only the para-linkage isomer displays ESIPT. In m-PITPE with meta-linkage, the electron cloud distribution only locates at the TPE part in the singlet excited (S1) states, which results in the localized excited state without ESIPT characteristic. 相似文献
102.
In the present work, three novel phenols (10a,11‐dihydro‐4bH‐indeno[1,2‐b]quinolin‐4‐ol ( 1 ), 5,6‐dihydro‐benzo[c]acridin‐1‐ol ( 2 ), and 5,5,7,7a‐tetrahydro‐4aH‐13‐aza‐benzo[3,4]cyclohepta[1,2‐b]naphthalene‐1‐ol ( 3 )) have been explored theoretically in detail. Using density functional theory (DFT) and time‐dependent DFT (TDDFT) methods, we inquire into the intramolecular hydrogen‐bonding interactions and the excited‐state intramolecular proton transfer (ESIPT) process. Exploring the steady‐state absorption and emission spectra under TDDFT/B3LYP/TZVP theoretical level in acetonitrile solvent, our calculated results demonstrate an experimental phenomenon. Based on analysis of the variations of geometrical parameters and infrared (IR) vibrational spectra, we confirm that O–H?N should be strengthened in the S1 state. Investigating the frontier molecular orbitals (MOs) and the charge density difference (CDD) maps, it can be confirmed that the charge redistribution facilitates the tendency of the ESIPT process for 1 , 2, and 3 systems. By constructing potential energy curves, we confirm that the proton transfer should occur in the S1 state. In particular, the ESIPT for 2 and 3 systems are nonbarrier processes in the S1 state, which confirms that ESIPT should be exothermal spontaneously. This work explains previous experimental results and makes a reasonable assumption about the ESIPT mechanism for 1 , 2 and 3 systems. We sincerely hope our work can facilitate understanding and promoting applications about them in future. 相似文献
103.
3-羟基黄酮在不同极性和酸碱度溶剂中的光谱研究 总被引:2,自引:0,他引:2
实验观测了3-羟基黄酮(3-HF)在不同极性溶剂中的吸收光谱和荧光光谱,发现在吸收光谱中有3个吸收带,峰值位于300和345 nm的两个吸收带较强,位于415 nm处的吸收带较弱。用345 nm作为激发光,观测到两个荧光带,其中峰值位于400 nm的荧光带为3-HF稀醇式构型的发射,随着溶剂极性的增大其强度增强,峰值位于526 nm的荧光带为3-HF互变异构体的发射,随着溶剂极性的增大其强度减弱,这表明溶剂极性阻碍质子转移的发生。用415 nm的光激发样品,在荧光光谱中发现了3个新荧光谱带,峰值分别位于440,471和515 nm,这3个荧光谱带归属至今未见报道。为了指认这3个荧光谱带,分别观测了3-HF在不同酸碱度溶液的荧光光谱及其吸收光谱,通过对这些光谱的分析研究,指认出荧光峰位于440和471 nm的荧光谱带为3-HF的两种阳离子的发射,峰值位于515 nm的荧光谱带为3-HF的阴离子的发射。 相似文献
104.
All-optical switching and nonlinear optical properties of HBT in ethanol solution 总被引:1,自引:0,他引:1 下载免费PDF全文
This paper demonstrates an all-optical switching
model system comprising a single pulsed pump beam
at 355 nm and a CW He--Ne signal beam at 632.8 nm with 2-(2^\prime
-hydroxyphenyl)benzothiazole (HBT) in ethanol solution. The origins
of the optical switching effect were discussed. By the study of
nonlinear optical properties for HBT in ethanol solvent, this paper
verified that the excited-state intramolecular proton transfer
(ESIPT) effect of HBT and the thermal effect of solvent worked on
quite different time scales and together induced the change of the
refractive index of HBT solution, leading to the signal beam
deflection. The results indicated that the HBT molecule could be an
excellent candidate for high-speed and high-sensitive optical
switching devices. 相似文献
105.