Temperature and solvent effects on rotamer-specific photobehaviour of the cis and trans isomers of 2-styrylanthracene

“…The solvent could affect the mixing between the two states and then the experimental k F values. 43,44 Irradiation at 400 nm generates vibrationally hot levels of the lowest excited singlet state of the substrates 1 and 2 which reach within about ten picoseconds the relaxed S 1 state. This state decays in about 300 ps and 30 ps for 1 and 2, respectively.…”

Section: Interaction Mechanismmentioning

confidence: 99%

Photophysics of aromatic thiourea derivatives and their complexes with anions. Fast and ultrafast spectroscopic investigations

Giacco

Carlotti

Solis

et al. 2010

Phys. Chem. Chem. Phys.

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In order to collect detailed information on the interaction mechanism between fluorescent thiourea derivatives and anions, 9-[4-(trifluoromethyl)phenylthioureidomethyl]anthracene (1) and the corresponding 10-cyanoanthracene derivative (2) were synthesized and investigated in DMSO and MeCN by using absorption and emission steady state techniques, both in the absence and in the presence of different anions (AcO(-), H(2)PO(4)(-), HSO(4)(-), and Br(-)). A wide examination of the mechanism of anion recognition was also performed by time-resolved transient absorption spectroscopy, with nano- and femto-second time resolution. A complete picture of the excited state deactivation pathways of 1 and 2, where the main operative processes were fluorescence, intersystem crossing and internal conversion, was obtained. Even if steady-state measurements suggest that 1 and 2 selectively interact in the ground state with the anions H(2)PO(4)(-) and AcO(-), time-resolved investigations demonstrate that the substrates are able to complex all the four anions. The photophysics of such complexes was fully characterized. The anions mainly modify the lifetime of the lowest excited singlet state and, especially in the cases of H(2)PO(4)(-) and AcO(-), the efficiencies of fluorescence emission and triplet formation. In particular, no evidence was found of further deactivation processes such as photoinduced electron transfer, photodissociation, and photoionization.

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“…[14][15][16] The further increase in the π-system by 4 electrons gives rise to 2-styrylanthracene (SA, 22 electrons), at which the ϕ tc value reduces practically to zero. 17,18 Since the cis-isomer remains reactive (the cis → trans photoisomerization quantum yield ϕ ct >0), the photochemical properties of SA are characterized as a 'one-way' cis → trans photoisomerization reaction. The sharp ϕ tc decrease when the π-system exceeds some threshold size, which is the so-called 'size effect', is explained by the change in the reaction mechanism from diabatic (nonadiabatic) to adiabatic: upon excitation of the cisisomer, the system 'slides' along the excited-state potential energy surface (PES) to the trans-isomer (adiabatic mechanism) passing the perp-conformer ( phantom state), where it could branch between trans-and cis-isomers (diabatic mechanism, see below).…”

Section: Introductionmentioning

confidence: 99%

Visible-light-driven two-way photoisomerization of 1-(1-pyrenyl)-2-(2-quinolyl)ethylene in neutral and protonated forms

Будыка

2018

Photochem Photobiol Sci

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Diarylethylenes with large π-systems often lose their photochemical activity (the size effect). 1-(1-Pyrenyl)-2-(2-quinolyl)ethylene (1P2QE), despite having a large conjugated π-system of 28 electrons, undergoes two-way reversible trans-cis photoisomerization both in the neutral and protonated forms with quantum yields as high as 0.13-0.83. For the neutral 1P2QE, experimental data and quantum-chemical calculations indicate a diabatic (nonadiabatic) reaction mechanism. Due to high photoisomerization quantum yields and the long-wavelength absorption band at 340-460 nm and 390-560 nm for the neutral and protonated compounds, respectively, 1P2QE can be used as a molecular photoswitch that is sensitive to visible light.

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Temperature and solvent effects on rotamer-specific photobehaviour of the cis and trans isomers of 2-styrylanthracene

Cited by 16 publications

References 37 publications

Photoisomerization mechanisms and photoselectivity of the stereoisomers of 1-(pyrid-n-yl),4-phenylbuta-1,3-diene

Photoisomerization mechanisms and photoselectivity of the stereoisomers of 1-(pyrid-n-yl),4-phenylbuta-1,3-diene

Photophysics of aromatic thiourea derivatives and their complexes with anions. Fast and ultrafast spectroscopic investigations

Visible-light-driven two-way photoisomerization of 1-(1-pyrenyl)-2-(2-quinolyl)ethylene in neutral and protonated forms

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