Steric hindrance-induced dual fluorescence of congested benzenehexacarboxylates

Yamasaki, Noritsugu; Inoue, Yoshihisa; Yokoyama, Taizo; Tai, Akira; Ishida, Akihiro; Takamuku, Setsuo

doi:10.1021/ja00006a011

Cited by 22 publications

(27 citation statements)

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“…We have noticed a relative increase of the weight of the SW emission with respect to the LW one at low temperature, whereas at RT the SW component is very weak or even absent. These results, also observed in the case of benzenehexacarboxylates, 30 have two meanings. First, they indicate that the SW component corresponds to the deexcitation of the less relaxed, more twisted rotamer of perylene orange in its excited state, and second, this rotamer is separated from the fully relaxed, more planar state by an activation barrier at least on the order of the LT thermal energy.…”

Section: Iii2 Comparison Between Low-and Room-temperature Spectrasupporting

confidence: 59%

“…From this point of view, perylene orange has a behavior close to that of congested benzenehexacarboxylates 30 and has also a similarity to the case of N-phenyl-2,3-naphthalimide. 21 It has been noticed in the latter case that the imide biscarbonyl group has a partial acceptor character, resulting from the presence of a partial charge transfer from the N to the O atoms of the carbonyl groups, in the ground state of the molecule.…”

Section: Iii2 Comparison Between Low-and Room-temperature Spectramentioning

confidence: 82%

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Existence of Conformers Revealed by Spectral Analysis of Single Molecules of Perylene Orange in Thin Sol−Gel Films

Julien¹,

Débarre²,

Nutarelli³

et al. 2006

J. Phys. Chem. B

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This paper reports on the spectral dynamics of perylene orange in thin sol-gel films. The studies are performed at the single molecule level to retrieve local information on such samples. The fluorescence spectrum of a molecule depends on the properties of the molecule itself and especially on its conformation in the ground state and in the state reached after excitation. Studies have been performed at room temperature and at a lower temperature, around 173 K. A large number of the recorded spectra reflect dual fluorescence. It is the rule at room temperature. However, at low temperature, single molecules either are relatively free to change conformation or are caught in a rigid environment. In the latter case, they present the spectrum of a rigid dye and we have identified the signature of several conformers of perylene orange in the ground state.

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Section: Iii2 Comparison Between Low-and Room-temperature Spectrasupporting

confidence: 59%

Section: Iii2 Comparison Between Low-and Room-temperature Spectramentioning

confidence: 82%

Existence of Conformers Revealed by Spectral Analysis of Single Molecules of Perylene Orange in Thin Sol−Gel Films

Julien¹,

Débarre²,

Nutarelli³

et al. 2006

J. Phys. Chem. B

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“…1,3,5-TrCB [56], 1,2,4-TrCB [56], DCN [57], DCP [10], DCP-Me [10], ME [58], PME [11] and OXA [59] were obtained by known procedures. Since oxygen could interact with the photogenerated radical anions, resulting in a back oxidation [6], all of the experiments were carried out in freeze–pump–thaw deoxygenated solutions, except where otherwise noted.…”

Section: Methodsmentioning

confidence: 99%

“…The potentials measured were then referred to SCE, applying the equation E (versus SCE) = E (versus Ag/AgCl; 3 M NaCl) − 35 mV. The redox potential of the excited state of compounds TCB [8–9], DCN [8–9], DCA [8–9], DCP [10] and DCP-ME [10] were taken from the literature, whereas the redox potentials of the excited state of 1,3,5-TrCB [21], 1,2,4-TrCB [21], ME [58] and PME [28] were determined by the Rehm–Weller equation [63]. …”

Section: Methodsmentioning

confidence: 99%

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

Fagnoni¹,

Protti²,

Ravelli³

et al. 2013

Beilstein J. Org. Chem.

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SummarySteady-state irradiation in neat acetonitrile of some aromatic nitriles, imides and esters (10−5–10−3 M solution) in the presence of tertiary amines allowed the accumulation of the corresponding radical anions, up to quantitative yield for polysubstituted benzenes and partially with naphthalene and anthracene derivatives. The condition for such an accumulation was that the donor radical cation underwent further evolution that precluded back electron transfer and any chemical reaction with the radical anion. In fact, no accumulation occurred with 1,4-diazabicyclo[2.2.2]octane (DABCO), for which this condition is not possible. The radical anions were produced from benzene polyesters too, but decomposition began early. Ipso substitution was one of the paths with secondary amines and the only reaction with tetrabutylstannane. The results fully support the previously proposed mechanism for electron transfer (ET) mediated photochemical alkylation of aromatic acceptors via radical ions and radical intermediates.

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“…Solvent and Temperature Effects: Analogous to the enantiodifferentiation mechanism established for the conventional intermolecular photosensitized enantiodifferentiating isomerization of cyclooctene, [17][18][19] the de of 1E-3E produced upon self-sensitized photoisomerization of 1Z-3Z is considered to be determined in the diastereodifferentiating rotational relaxation of the prochiral C=C bond within the exciplex intermediate. Since alkyl benzoates, including these substrates, are not fluorescent in general, 28 the nature of intervening exciplex was evaluated by examining the solvent effect on product de. Thus, if the exciplex possesses a high charge-transfer (C-T) character, the use of polar solvents should enhance the ionic dissociation of the intervening exciplex, resulting in a much decreased, or zero, de.…”

Section: Conversion Dependencementioning

confidence: 99%

Self-Sensitized DiastereodifferentiatingZ-EPhotoisomerization of 3-, 4-, and 5-Benzoyloxycyclooctenes: Intra- versus Intermolecular Photosensitization

Matsuyama¹,

Inoue²,

Inoue³

2004

Synthesis

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Upon irradiation at 254 nm, (Z)-3-, 4-, and 5-benzoyloxycyclooctenes (1Z-3Z) efficiently isomerized through intraand/or intermolecular sensitization to the corresponding diastereomeric E-isomers (1E-3E) with low to moderate diastereomeric excesses (de's) of up to 43%. The major diastereomer produced from 1Z was switched from (1R*,3R*)-1E (26% de) to (1R*,3S*)-1E (-11% de) by simply increasing the substrate concentration from 1 mM to 50 mM. This unusual switching of product chirality is attributed to the opposite diastereoselectivities for intra-and intermolecular photosensitization. In contrast, 2Z and 3Z did not show such switching behavior, but consistently gave a single diastereomer of up to 9% and 43% de, respectively, over a wide range of substrate concentrations (0.04-50 mM), for which totally different mechanisms are responsible. Thus, the intra-and intermolecular sensitizations of 2Z exhibit the same diastereoselectivity, while only the intermolecular sensitization of 3Z can occur as a result of the hindered intramolecular approach of the benzoate substituent to the cyclooctene moiety.

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Steric hindrance-induced dual fluorescence of congested benzenehexacarboxylates

Cited by 22 publications

References 1 publication

Existence of Conformers Revealed by Spectral Analysis of Single Molecules of Perylene Orange in Thin Sol−Gel Films

Existence of Conformers Revealed by Spectral Analysis of Single Molecules of Perylene Orange in Thin Sol−Gel Films

Spectroscopic characterization of photoaccumulated radical anions: a litmus test to evaluate the efficiency of photoinduced electron transfer (PET) processes

Self-Sensitized DiastereodifferentiatingZ-EPhotoisomerization of 3-, 4-, and 5-Benzoyloxycyclooctenes: Intra- versus Intermolecular Photosensitization

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