Excited-state dynamics of jet-cooled substituted indoles:  the role of polar interactions in 1La-1Lb state coupling

Demmer, David; Leach, Gary W.; Outhouse, E. Allison; Hager, James W.; Wallace, Stephen C.

doi:10.1021/j100365a018

Cited by 44 publications

(36 citation statements)

References 3 publications

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“…For a nonpolar "inert" solvent like cyclohexane, it is reasonable that an approximate mapping between solution and free jet lifetimes is given by compound rMln (ns) bIoh rjet (ns) 5-MI 9.8 0.38 18.6 indole (I) 9.0 0.33 17. 6 7-MI 7.8 0.27 15.0 3-I-acetonitrile 8 5-methoxy-I 6.9 0.43 15.3 1-MI 6.5 0.44 17.7 4-I-carboxylic acid 3.6 0.26 4 7.9 (B) 2,3-DMI 2.6 0.23 6.3 I = indole. Letters A and B denote different conformer origins in the jet-cooled sample spectra.…”

Section: Methodsmentioning

confidence: 99%

Fluorescence lifetimes of substituted indoles in solution and in free jets: evidence for intramolecular charge-transfer quenching

Arnold¹,

Tong²,

Sulkes³

1994

J. Phys. Chem.

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Fluorescence lifetime measurements for a variety of substituted indoles were taken in cyclohexane and in supersonic gas expansions. When the two data sets were compared, a strong trend became evident. Solvent polarizability effects can be seen as stabilizing intramolecular charge-transfer quenching processes in the substituted indoles that are stimulated by the correct placement of charge accepting/releasing substituents.

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Section: Methodsmentioning

confidence: 99%

Fluorescence lifetimes of substituted indoles in solution and in free jets: evidence for intramolecular charge-transfer quenching

Arnold¹,

Tong²,

Sulkes³

1994

J. Phys. Chem.

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“…26 Wallace's group initially proposed indolylic N-H bond dissociation in 1 L a as the radiationless process. 10,11 Evidence pointing to this conclusion is the significant increase in bare molecule lifetimes in DMI-d 1 and also in HC-d 1 , where the N-H has been replaced by N-D. 11 We tried to verify an N-H bond dissociation channel in bare DMI using mass-resolved spectra. Excitation spectra were carried out in which time-of-flight mass waveforms were taken to cover the parent m/e ) 147 channel as well as lower mass channels.…”

Section: -Methoxyindole (5-moi)mentioning

confidence: 99%

“…[1][2][3] (2) More generally, and much more extensively, small clusters of indoles have been studied with a variety of polar solvents. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] Indole was found to have two separate polar binding sites. 9 One, based on a correlation between the 0 0 0 frequency of the cluster species and solvent proton affinity, appears to be in the vicinity of the pyrrole N-H. 8 The other has been proposed to be adjacent to the pyrrole π density in the vicinity of C-3, where the solvent acts as partial proton donor.…”

Section: Introductionmentioning

confidence: 99%

Jet-Cooled Solvent Complexes with Indoles

and

Sulkes

1996

J. Phys. Chem.

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Cold mass-resolved excitation spectra have been obtained for substituted and unsubstituted indoles complexed with one or two polar solvent molecules. Frequency scans were carried out to more than 1000 cm -1 above the complex origins. Sharp excitation features persisted to the blue for the N-H site complexes, but no features further to the blue were attributable to the π site complexes. In 3-methylindole a number of vibrations 400-900 cm -1 above the S 1 origin in the bare chromophore did not appear in corresponding locations above the S 1 complex origins for n ) 1 water and methanol clusters. It is likely that these peaks underwent much greater red shifts in the complexes than the S 1 origins because the former possess substantial 1 L a character. Any of the indoles studied that was complexed with two polar solvent molecules showed broad excitation features. The extended structure most likely arises in at least some instances because of π site interactions. In 2,3-dimethylindole, postulated to undergo N-H bond dissociation in S 1 , mass-resolved REMPI spectra did not disclose a lower mass product arising from N-H bond breaking. However, when the chromophore was complexed at the N-H site with a strong proton acceptor, triethylamine, evidence was found that zwitterions were formed in the S 1 complex arising from N-H site proton donation to the base.

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“…( 1 L a state), see also Figure 2. For aromatic molecular systems such as indoles, [27][28][29][30][31][32][33] tryptophane, [34] or pyrene derivatives [35] internal conversion between these 1 L b and 1 L a levels has been suggested in the interpretations. For 1-naphthol [36,37] the 1 L b !…”

Section: Introductionmentioning

confidence: 99%

Solvent‐Dependent Photoacidity State of Pyranine Monitored by Transient Mid‐Infrared Spectroscopy

et al. 2005

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We investigate with femtosecond mid‐infrared spectroscopy the vibrational‐mode characteristics of the electronic states involved in the excited‐state dynamics of pyranine (HPTS) that ultimately lead to efficient proton (deuteron) transfer in H2O (D2O). We also study the methoxy derivative of pyranine (MPTS), which is similar in electronic structure but does not have the photoacidity property. We compare the observed vibrational band patterns of MPTS and HPTS after electronic excitation in the solvents: deuterated dimethylsulfoxide, deuterated methanol and H2O/D2O, from which we conclude that for MPTS and HPTS photoacids the first excited singlet state appears to have charge‐transfer (CT) properties in water within our time resolution (150 fs), whereas in aprotic dimethylsulfoxide the photoacid appears to be in a nonpolar electronic excited state, and in methanol (less polar and less acidic than water) the behaviour is intermediate between these two extremes. For the fingerprint vibrations we do not observe dynamics on a time scale of a few picoseconds, and with our results obtained on the OH stretching vibration we argue that the dynamic behaviour observed in previous UV/Vis pump–probe studies is likely to be related to solvation dynamics.

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Excited-state dynamics of jet-cooled substituted indoles: the role of polar interactions in 1La-1Lb state coupling

Cited by 44 publications

References 3 publications

Fluorescence lifetimes of substituted indoles in solution and in free jets: evidence for intramolecular charge-transfer quenching

Fluorescence lifetimes of substituted indoles in solution and in free jets: evidence for intramolecular charge-transfer quenching

Jet-Cooled Solvent Complexes with Indoles

Solvent‐Dependent Photoacidity State of Pyranine Monitored by Transient Mid‐Infrared Spectroscopy

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