ChemInform Abstract: EXPERIMENTAL AND QUANTUM CHEMICAL INVESTIGATIONS OF DIPOLE MOMENTS OF SUBSTITUTED STILBENES IN THE FIRST EXCITED SINGLET STATE

Kawski, A.; Gryczyński, Ignacy; Jung, Ch.; Heckner, K.‐H.

doi:10.1002/chin.197729054

Cited by 7 publications

(16 citation statements)

References 1 publication

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“…For 1 the Stokes shift has previously been examined in terms of a BilotKawski relationship [19]. Values of |i g =7 and |i e ~ 22 Debye calculated with this method agree with those obtained by other methods [10,19,20].…”

Section: Absorption and Fluorescence Emission Propertiessupporting

confidence: 62%

“…Grabowski et al have shown that the origin of the long wavelength fluorescence component is to be attributed to a twisted intramolecular charge transfer (TICT) state in which the dimethylamino group is perpendicular to the phenyl ring [2]. The emission properties of trans-stilbenes, substituted in the 4 and 4' positions by electron donating and accepting groups, also depend markedly on intramolecular charge transfer interaction [9][10][11][12][13][14][15][16][17][18][19][20]. The question arises therefore whether or not a TICT state is also involved in the deactivation of trans-4-cyano-4'-dimethylaminostilbene (trans-1) which may be regarded as an extended DAB-structure.…”

Section: Introductionmentioning

confidence: 99%

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Fluorescence of Trans-4-Cyano-4′-dimethylaminostilbene; No Evidence for a TICT State

Gruen

Görner

1983

Zeitschrift Für Naturforschung A

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The fluorescence properties of trans-4-cyano-4'-dimethylaminostilbene (trans-1) and a rigid analogue, in which the dimethylaminophenyl group is replaced by an indoline ring, trans-1-(4-cyanophenyl)-2-(5-[2,3-dihydro]N-methylindolyl)ethylene (trans-2) were studied in 20 solvents. The quantum yields of fluorescence (tf> f ) and of trans-»eis photoisomerization (<2>t-c) as well as the fluorescence maximum (v f ) and the bandwidth (zlv f ) were examined. The activation energies (range: 3.5-7.8 kcal/mol) obtained from <2> f and <£ t _ c measurements are nearly the same for 1 and 2 in a given solvent. 0 f , v f and Jv f as a function of solvent polarity and temperature show similar trends for 1 and 2. No dual emission was observed for either of the cyanostilbenes. These findings indicate that a twisted intramolecular charge transfer (TICT) state is not involved in the relaxation process of the first excited trans singlet state ('t*). The main deactivation pathway of 't* competing with fluorescence is trans eis photoisomerization by twisting about the C = C double bond in the first excited singlet state for both.

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Section: Absorption and Fluorescence Emission Propertiessupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Fluorescence of Trans-4-Cyano-4′-dimethylaminostilbene; No Evidence for a TICT State

Gruen

Görner

1983

Zeitschrift Für Naturforschung A

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“…The values of these coefficients and the discriminants are given in Table III. The values of electric dipole moments in the excited state μe , thus obtained for known [17][18][19] dipole moments in the ground state, μg , have also been given in Table III. In order to verify such a simplified method of determining the values of the dipole moments μe in the excited state, μe was also determined by the method of Liptay [9,10] for one of the substances investigated and denoted by 1h.…”

Section: Resultsmentioning

confidence: 99%

“…Hence, based on the equations (4) and (5), μeA = 60.5 x 10 -30 Cm and μen = 58.9 x 10 -30 Cm were obtained which are in very good accordance with the value of μe determined from the equation (6) (see Table III). Table I1I summarizes also the values of dipole moments μe determined by the solvent method [17][18][19], by dichroism [20], and by Czekalla's method of polarization in electric field [6,10]. Considerable differences have been observed for molecules lá, lh, j, 1k, 1m, 1n, which can be accounted for by the fact that in Liptay's equations (1), (3), and (6), the effective electric field was represented by the Lorentz field whereas in the solvatochromic method by the Onsager field.…”

Section: Resultsmentioning

confidence: 99%

“…Based on the theoretical considerations of Baumann and Deckers [22] and applying the Onager model for a spherical cavity [23] and the approximation (α/α3)(1/(4πε0 )) = 1/2 (where α is the polarizability, α -the Onsager interaction radius of the solute, and ε, -the permittivity of vacuum [17], the following expression is obtained for luminescent molecules in nonpolar solvent (the experiments were carried out in cyclohexane with permittivity εDK = 2.023 at T = 295 K):…”

Section: Resultsmentioning

confidence: 99%

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Anisotropic Fluorescence of Polar Molecules in External Electric Field, Dipole Moments of Para-Disubstituted Transstilbenes in the First Excited Singlet State

Kawski

Kubicki

1991

Acta Phys. Pol. A

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The electric dipole moments μe in the lowest excited singlet state of nine short-lived para-disubstituted trans-stilbenes were determined experimentally based on the effect of the external electric freld on the fluorescence anisotropy. The values of μe obtained from Liptay's theory with the employment of the Onsager effective field are in satisfactory agreement with those calculated based on the solvatochromic effect. In the case of para-substituted trans-stilbenes with the same donor substituent R = Ν(CH3)2 in position 4 and different acceptors R, in position 4,, the enhancing electron properties of the acceptor are accompanied by the increase in μg -the dipole moment in the ground state, and μ -the dipole moment in the excited state. There exists a linear relation between the values of μc and μ5 .

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Femtosecond dynamics of intramolecular charge transfer in 4-dimethylamino-4′-cyanostilbene in polar solvents

Eilers-König

Kühne

Schwarzer

et al. 1996

Chemical Physics Letters

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The femtosecond dynamics of 4-(N,N-dimethylamino)-4'-cyanostilbene (DCS) in acetonitrile and methanol solvent was studied by fluorescence upconversion and pump-probe absorption spectroscopy. The spectral evolution observed provides strong evidence for a fast internal charge-transfer (CT) process dominating the dynamics in the first few picoseconds, while Stokes shift dynamics seem to play only a minor role. The initially excited state seems to have already a large amount of CT character, in line with observations in jet-cooled DCS-solvent clusters. The non-exponential CT-state formation contains components significantly faster than longitudinal dielectric relaxation rates in the solvents studied, indicating a possible contribution by high-frequency vibrational modes.

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ChemInform Abstract: EXPERIMENTAL AND QUANTUM CHEMICAL INVESTIGATIONS OF DIPOLE MOMENTS OF SUBSTITUTED STILBENES IN THE FIRST EXCITED SINGLET STATE

Cited by 7 publications

References 1 publication

Fluorescence of Trans-4-Cyano-4′-dimethylaminostilbene; No Evidence for a TICT State

Fluorescence of Trans-4-Cyano-4′-dimethylaminostilbene; No Evidence for a TICT State

Anisotropic Fluorescence of Polar Molecules in External Electric Field, Dipole Moments of Para-Disubstituted Transstilbenes in the First Excited Singlet State

Femtosecond dynamics of intramolecular charge transfer in 4-dimethylamino-4′-cyanostilbene in polar solvents

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