Tunable Anti‐Stokes‐Shift Behaviors Based on Intramolecular Charge Transfer Characteristics of Diarylethene Derivatives

2021 ◽  
pp. 2102180
Author(s):  
Yonghong Shi ◽  
Jianlei Han ◽  
Xue Jin ◽  
Pengfei Duan
Keyword(s):  
Charge Transfer ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Transfer Characteristics ◽  
Anti Stokes

Spectroscopic Studies of Dimethylamino Derivatives of Fluorene

2000 ◽  
Vol 55 (11-12) ◽  
pp. 902-908 ◽  
Author(s):  
J. Heldt ◽  
J. R. Heldt ◽  
T. Redzimski ◽  
H. Diehl ◽  
P. Schultz
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Fluorescence Spectra ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Spectroscopic Studies ◽  
Polar Solvents ◽  
Derivatives Of ◽  
Transfer State

Abstract 2-dimethylamino-9-fluorenol and 2-dimethylamino-9(4'dimethylamino)phenyl-9-fiuorenol in polar solvents in the excited state undergo conformation changes in which two fluorescent isomers are created. The isomers (in the local excited (LE) and charge transfer (CT) configuration) possess separate fluorescence bands, one appearing from the S1 (LE) state and the second from the intramolecular charge transfer state S1 (CT) of the neutral, aromatic molecule. Both bands show a solvatochromic effect. Using the method of the solvent induced Stokes shift of the absorption and fluorescence spectra the permanent dipole moment of the excited state of fluorene and its two derivatives have been determined. The dipole moment of the ground state and the Onsager cavity radius of the studied molecules were calculated with the Auestion Model 1 (AM1) program.

Increasing the anti-Stokes shift in TTA upconversion with photosensitizers showing red-shifted spin-allowed charge transfer absorption but a non-compromised triplet state energy level

2019 ◽  
Vol 55 (10) ◽  
pp. 1510-1513 ◽  
Author(s):  
Zhijia Wang ◽  
Jianzhang Zhao ◽  
Mariangela Di Donato ◽  
Gloria Mazzone
Keyword(s):  
Charge Transfer ◽  
Absorption Band ◽  
Energy Level ◽  
Triplet State ◽  
State Energy ◽  
Stokes Shift ◽  
Spin Orbit ◽  
Triplet State Energy ◽  
Anti Stokes

Excitation into the 1CT absorption band of a spin–orbit charge transfer ISC triplet photosensitizer increases the anti-Stokes shift in TTA upconversion.

Diagnosis of Fatty Liver Disease by a Bright, Multiphoton-Active and Lipid-Droplet-Specific AIEgen with Nonaromatic Rotors

2020 ◽  
Author(s):  
Hojeong Park ◽  
Shijie Li ◽  
Guangle Niu ◽  
Haoke Zhang ◽  
Zhuoyue Song ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Liver Disease ◽  
Fatty Liver ◽  
Lipid Droplet ◽  
Fatty Liver Disease ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Transfer Effect ◽  
Photon Absorption ◽  
Two Photon

Fatty liver disease (FLD) has become an increasing global health risk. However, an accurate diagnosis of FLD at an early stage remains a great challenge due to lack of suitable imaging tools. To this end, we developed the first fluorescent two-photon aggregationinduced emission (AIE) luminogen ABCXF for high-contrast imaging of FLD tissue. ABCXF has a large Stokes shift, good two-photon absorption cross-section, bright red emission, high fluorescence quantum yield in solid state, and excellent photostability. It shows abnormal intramolecular charge transfer effect instead of twisted intramolecular charge transfer effect in polar solvents. Photophysical and crystal data demonstrated that it exhibits nonaromatic rotors - trifluoromethyto contribute to its AIE effect. Biocompatible lipid droplet-targeting ABCXF can selectively light up lesions in the FLD tissue with a high signal-to-noise ratio. It shows superior imaging performances compared to Oil Red O. Thus, ABCXF can be a powerful tool for the diagnosis and evaluation of FLD from a liver biopsy.

Intramolecular fluorescence quenching in aminocoumarines. Identification of an excited state with full charge separation

1985 ◽  
Vol 63 (7) ◽  
pp. 1649-1653 ◽  
Author(s):  
Wolfgang Rettig ◽  
André Klock
Keyword(s):  
Dipole Moment ◽  
Excited State ◽  
Charge Transfer ◽  
Fluorescence Quenching ◽  
Charge Separation ◽  
Intramolecular Charge Transfer ◽  
Stokes Shift ◽  
Twisted Intramolecular Charge Transfer ◽  
Full Charge

The fluorescence of 6-aminocoumarine (A6C) is very weak and anomalously redshifted as compared to its 7-substituted analogues 4-methyl-7-aminocoumarine (A7C) and 4-methyl-7-diethylaminocoumarine (DEA7C). The solvatochromic redshift in homologous alcohols is much stronger for A6C, pointing to an increased dipole moment of the emitting state. A twisted intramolecular charge transfer (TICT) state with full charge separation is made responsible for this emission. This is rationalized by molecules-in-molecules calculations. The strong Stokes shift in n-hexane and in ethanol glass at 77 K suggests that A6C emits from a TICT state even under these conditions.

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