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Fluorescence 4- benzonitrile

Il ichev YV, Kuhnle W, Zachariasse KA (1998) Intramolecular charge transfer in dual fluorescent 4-(dialkylamino) benzonitriles. Reaction efficiency enhancement by increasing the size of the amino and benzonitrile subunits by alkyl substituents. J Phys Chem A 102(28) 5670-5680... [Pg.302]

Schuddeboom W, Jonker SA, Warman JM, Leinhos U, Kiihnle W, Zachariasse KA (1992) Excited-state dipole moments of dual fluorescent 4-(dialkylamino) benzonitriles. Influence of alkyl chain length and effective solvent polarity. J Phys Chem 96 10809-10819... [Pg.302]

With instruments based on fluorescence up-conversion (see Chapter 11) that offer the best time resolution (about 100 fs), such a fast inertial component was indeed detected in the fluorescence decayc,d). Using coumarin 153 as a solute (whose dipole moment increases from 6.5 to 15 D upon excitation), the inertial times of acetonitrile, dimethylformamide, dimethyl sulfoxide and benzonitrile were found to be 0.13, 0.20, 0.17 and 0.41 ps, respectively. ... [Pg.210]

K. Rotkiewicz, K. H. Grellmann, and Z. R. Grabowski, Reinterpretation of the anomalous fluorescence ofP-N,N-dimethylamino-benzonitrile, Chem. Phys. Lett. 79,315 (1973). [Pg.142]

V,/V-Dimethylamino)benzonitrile (DMABN) and its derivatives, as a class of organic donor-acceptor compounds, exhibit dual fluorescence, one related to the local excited state ( B band) and the other ascribed to the twisted intramolecular charge transfer (TICT) state ( A band).17 As expected, compound 818 exhibits dual fluorescence, showing two fluorescence bands centered at 350 and 432 nm, which can be ascribed to the corresponding band (from the local excited state) and A band (from the TICT state), respectively. After oxidation of TTF unit in 8, the fluorescence intensity of A band decreases while that of band increases slightly. As expected, further reduction of TTF" + into neutral TTF unit leads to the restoration of the fluorescence spectrum of 8. Therefore, the dual fluorescence spectrum of 8 can be reversibly modulated by redox reactions of TTF unit in 8. [Pg.451]

For alcohol solvents, measurements were made with time-correlated single photon counting. The remaining measurements were made with the fluorescence upconversion system. The transients in alcohol solvents were fitted with a single exponential kinetic function. The kinetics in acetone is also well described by a single exponential, but in benzonitrile, dimethyl-sulfoxide, and propylene carbonate the kinetics were modeled with a biexponential decay. [Pg.56]

In the case of compound 32, no change in the absorption spectrum compared with that of 33 could be observed, neither in cyclohexane nor in benzonitrile. This indicates that intramolecular CT interaction is negligible in the ground-state. Nevertheless, fluorescence and transient absorption spectroscopy show that processes after excitation strongly depends on solvent polarity. In cyclohexane the Si state... [Pg.676]

Fig. 9.44 Room temperature fluorescence spectra of 18b in toluene (dark orange), THF (light orange) and benzonitrile (yellow) displaying the increasing quenching of the fullerene emission upon increasing solvent polarity... Fig. 9.44 Room temperature fluorescence spectra of 18b in toluene (dark orange), THF (light orange) and benzonitrile (yellow) displaying the increasing quenching of the fullerene emission upon increasing solvent polarity...
Fig. 9.56 Room temperature fluorescence spectra of the ZnP-reference (black) and 21b in toluene, THF and benzonitrile displaying the solvent dependence of the quenching of the porphyrin emission upon 345 nm excitation... Fig. 9.56 Room temperature fluorescence spectra of the ZnP-reference (black) and 21b in toluene, THF and benzonitrile displaying the solvent dependence of the quenching of the porphyrin emission upon 345 nm excitation...
The activated internal conversion, which is a hallmark of the photoexcited DNA bases, also occurs in a number of aromatic ethynes and nitriles, including dipheny-lacetylene (DPA) and 4-(dimethylamino)benzonitrile (DMABN). Thus, as in the case of the nucleobases, DPA exhibits an abrupt break-off (loss) of fluorescence in supersonic free jet [35], Figure 15-16, and the strong thermal quenching of... [Pg.411]

Figure 15-24. Fluorescence and absorption spectra of 4-(dimethylamino)benzonitrile (DMABN) in acetonitrile (ACN) and in n-hexane (HEX) at 25 °C... Figure 15-24. Fluorescence and absorption spectra of 4-(dimethylamino)benzonitrile (DMABN) in acetonitrile (ACN) and in n-hexane (HEX) at 25 °C...
The existence of two interconvertible ICT and TICT excited-state molecules can lead to a dual, variable solvent-dependent fluorescence. This dual fluorescence was first discovered by Lippert et al. [342] using 4-(dimethylamino)benzonitrile as the fluorescent compound, and then correctly interpreted by Grabowski et al. [343]. They identified the... [Pg.354]

The Twisted Intramolecular Charge Transfer (TICT) model was put forward by Grabowski and coworkers [2,3,15] to account for the observation that the dual fluorescence of DMABN with its normal band (B band) at around 350 nm and its anomalous one (A band, around 450 nm in medium polar solvents) depends on the conformational freedom of the dimethylamino (DMA) group For compounds like MIN, where the DMA group is more or less fixed to a coplanar conformation with the benzonitrile sceleton, and where the lone pair orbital on the amino nitrogen is nearly parallel to the carbon p-orbitals constituting the benzonitrile 7t-system, only the B band is observed. For the... [Pg.255]

The present discussion is restricted to D-A molecules which show dual fluorescence in solutions, i.e., 4-dialkylamino derivatives of benzonitrile (I-III, Figure... [Pg.3081]

Figure 6. Qustering of CHFj about (dimethylamino)benzonitrile at 50 C based on solvatochromic shifts in fluorescence (A data from ref. 26, — Onsager reaction field theory). Figure 6. Qustering of CHFj about (dimethylamino)benzonitrile at 50 C based on solvatochromic shifts in fluorescence (A data from ref. 26, — Onsager reaction field theory).

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See also in sourсe #XX -- [ Pg.354 , Pg.355 ]




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