The Excited State Behavior of Aminostilbenes. A New Example of the Meta Effect

Lewis, Frederick D.; Yang, Jye‐Shane

doi:10.1021/ja964465u

Cited by 73 publications

(72 citation statements)

References 29 publications

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“…Besides the N-arylamino conjugation effect, two other amino substituent effects that significantly raises the C¼C torsion barrier in favor of fluorescence are the meta-amino and para,para-diamino effects [59,60]. This is illustrated by the comparison of trans-3-aminostilbene (3AS) [54], trans-4-aminostilbene (4AS) [54], and trans-4,4 0 -bis(dimethylamino) stilbene (4DDS) [61,62] in cyclohexane or hexane (Chart 5), which possess a K f of 0.78, 0.05, and 0.81, respectively.…”

Section: The Meta-amino and Para Para-diamino Effectsmentioning

confidence: 99%

Fate of photoexcited trans-aminostilbenes

Yang

Lin

2015

Journal of Photochemistry and Photobiology A: Chemistry

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Section: The Meta-amino and Para Para-diamino Effectsmentioning

confidence: 99%

Fate of photoexcited trans-aminostilbenes

Yang

Lin

2015

Journal of Photochemistry and Photobiology A: Chemistry

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“…Similar differences in lifetime and reactivity have been observed for 3-versus 4-N,N-dimethylaminostilbene (3DS) and for derivatives of styrylnaphthalenes, styrylpyridines, and donor-acceptor substituted stilbenes. 1,3 The photochemistry of 4,4′-diaminostilbene and its tetramethyl derivative (4,4′AS and 4,4′DS, Chart 1) has been the subject of several investigations. [4][5][6][7][8] The singlet lifetimes of these molecules in nonpolar solvents are among the longest observed for a 4,4′-disubstituted stilbene (ca.…”

Section: Introductionmentioning

confidence: 99%

Relaxation Pathways of Photoexcited Diaminostilbenes. The meta-Amino Effect

2001

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The spectroscopy and photochemistry of several 3-substituted trans-diaminostilbenes have been investigated and the results compared with those from previous studies of 4,4′-diaminostilbenes. The excited-state properties of 3,5-diaminostilbene and 3,3′-diaminostilbene are similar to those for the parent 3-aminostilbene. These amines display long, temperature-independent singlet lifetimes and large fluorescence quantum yields. The long singlet lifetimes are a consequence of large barriers for torsion about the central double bond on the singlet state surface and low fluorescence rate constants. Thus, these diaminostilbenes display the "metaamino effect" previously identified for 3-aminostilbene and for some amine-donor-acceptor substituted stilbenes. The 4,4′-diaminostilbenes also have larger torsional barriers in nonpolar solvents but shorter singlet lifetimes as a consequence of larger fluorescence and intersystem crossing rate constants. The photophysical properties of 3,4′-dimethylaminostilbene are similar to those of 4,4′-aminostilbenes; however, it has a lower torsional barrier, similar to that of the parent 4-aminostilbene.

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“…This finding underscores that only ortho-and meta-transmission is characteristic of the first excited state of both substituted benzenes [12] and ethenylbenzenes [13], i.e., electron donors increase the p-electron densities at both the ortho-and metabut not at the para-position.…”

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confidence: 51%

“…1 H-NMR (CDCl 3 ): 7.76 (d, J 9.7); 7.28 (t, J 8.1); 6.73 (d, J 8.1); 6.55 (d, J 8.1); 6.32 (d, J 9.7); 4.14 (br. s, 2 NH) 13. C-NMR (CDCl 3 ): 161.0 (s); 155.4 (s); 143.9 (s); 137.6 (d); 132.7 (d); 113.8 (d); 110.6 (d); 107.1 (d); 106.7 (s).…”

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confidence: 98%

“…In contrast, both 8 and 9 selectively and exclusively afforded at l > 390 nm the monocycloadducts 23 and 24, respectively (Scheme 6). The structural assignment of 23 was achieved by comparing the chemical shifts of the carbonyl C-atoms in the 13 C-NMR spectrum (167 and 163 ppm), which clearly correlate with those of 3,4-dihydrocoumarin [8] and of quinolone [9] (168 ppm and 164 ppm) but not with coumarin [8] and 3,4-dihydroquinolone [10] (160 ppm and 172 ppm), respectively. For 24 (d (SÀCO) 183 ppm), the same criteria can be used to differentiate between a thiocoumarin and a 3,4-dihydrothiocoumarin (185 ppm and 199 ppm [11]).…”

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Site Selectivity in [2+2] Photocycloadditions of Tricyclic ‘Diethenylbenzenes' to 2,3-Dimethylbut-2-ene

Bethke

Margaretha

2002

HCA

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Upon irradiation at wavelengths above 390 nm in the presence of 2,3-dimethylbut-2-ene, both the newly synthesized pyranoquinolinedione 8 and thiinobenzopyrandione 9 selectively afford one of two possible photocycloadducts, 23 and 24, respectively.Introduction. ± Crosslinking of thymine units within helical DNA strands can be achieved, for instance, by light-induced reactions of psoralens (2H-furo[3,2-g]benzopyran-2-ones), such as 1, via two consecutive [2 2] photocycloadditions, the first one occuring at the furan double bond [1]. In contrast, photocycloadditions in solution of both linear (1) [2] and angular tricycles (2 and 3) [3] to alkenes selectively occur at the double bond of the six-membered heterocycle. This difference in selectivity has been attributed to the observation that the photocycloaddition to a nucleic acid is preceded by intercalation of a psoralen, the smaller furan moiety fitting into the helix [1] (Scheme 1).

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The Excited State Behavior of Aminostilbenes. A New Example of the Meta Effect

Cited by 73 publications

References 29 publications

Fate of photoexcited trans-aminostilbenes

Fate of photoexcited trans-aminostilbenes

Relaxation Pathways of Photoexcited Diaminostilbenes. The meta-Amino Effect

Site Selectivity in [2+2] Photocycloadditions of Tricyclic ‘Diethenylbenzenes' to 2,3-Dimethylbut-2-ene

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