Hydration dynamics of protons from photon initiated acids

Lee, J.; Robinson, G. W.; Webb, S. P.; Philips, Laura A.; Clark, J. H.

doi:10.1021/ja00281a016

Cited by 129 publications

(148 citation statements)

References 1 publication

(2 reference statements)

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“…In aqueous solution emission of the neutral form (1-naphthol) at 360 nm is very weak (φ f ) 0.002), while the intensity of the anion emission, at 460 nm, is moderately strong (φ f ) 0.114). 19 On addition of the surfactants, the emission intensity of the neutral and the anion of 1-naphthol, remains unchanged up to about 0.9 mM CTAB, 0.2 mM TX-100R, and 8 mM SDS which are close to the reported critical micellar concentration (cmc) 25 of these micelles ( Figure 2). Above cmc, at 96 mM CTAB, the neutral (360 nm) and the anion emission (at 460 nm) exhibit, respectively, nearly 20-and 6-fold increase in the emission intensity, compared to water ( Figure 1a).…”

Section: Methodssupporting

confidence: 67%

“…One of them gives exclusively the neutral emission and the other produces the anion emission. It seems that both in 90% methanol and inside the TX-100R and SDS micelles, all the probe 1-naphthol molecules do not get a large enough number (4 ( 1) 20,21 of water molecules in their immediate neigborhood to undergo the fast deprotonation. Those which get a sufficient number of water molecules undergo fast deprotonation to give exclusively the anion emission, while those which are less accessible to water molecules give predominantly the neutral emission.…”

Section: Discussionmentioning

confidence: 99%

“…9,18,19 This shows that the deprotonation of 1-naphthol is slowed by a factor of 20 on binding to CTAB. The lifetime of the decay of the anion emission is found to be 19 ( 0.5 ns which is nearly two times longer than the lifetime of the anion in water (8 ns).…”

Section: Steady-state Emission Spectramentioning

confidence: 92%

“…In alcohol, however, the deprotonation is markedly suppressed and only the neutral emission is observed. 19 Fleming et al demonstrated that in aqueous solutions the rate of deprotonation of protonated aminopyrene increases nearly 3 times when the probe binds with cyclodextrin, while for 1-naphthol the deprotonation becomes almost 20 times slower. 9 Although the effect of cyclodextrin, [8][9][10][11] lipids, 12 and different solvent mixtures 17,19-24 on the excited state proton transfer (ESPT) processes of 1-naphthol and other compounds is well studied, there has been little study on the effect of micelles on the ultrafast deprotonation of 1-naphthol.…”

Section: Introductionmentioning

confidence: 99%

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Excited-State Proton Transfer of 1-Naphthol in Micelles

1998

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The fast deprotonation of 1-naphthol, which occurs in 35 ps in aqueous solution, is studied in neutral (triton X 100, reduced, TX-100R), cationic (cetyl trimethylammonium bromide, CTAB), and anionic (sodium dodecyl sulfate, SDS) micelles. Drastically different effects on the proton transfer process and the relative emission intensities of the neutral form (360 nm) and the anion (460 nm) are observed in the three micelles. The intensities of the anion and the neutral emission of 1-naphthol exhibit a break around the reported critical micellar concentration (cmc) of the three micelles. Above cmc, intensity of the neutral emission is enhanced by a factor of nearly 90, 66, and 20 in 20 mM TX-100R, 200 mM SDS, and 96 mM CTAB, respectively. The anion emission is enhanced for CTAB and TX-100R, while for SDS its intensity decreases, compared to water. In CTAB, the rise time of the 460 nm emission (600 ( 100 ps) is similar to the lifetime of decay at 360 nm. However, for TX-100R and SDS, the rise time of the anion emission (at 460 nm) is found to be faster than the decay of the neutral emission (at 360 nm). This indicates that in TX-100R and SDS, there is no parental relation between the normal and the anion emission and they originate from the probe, 1-naphthol molecules, at distinctly different locations. The rise times at 460 nm are 1.8 ( 0.1 ns and 600 ( 100 ps for TX-100R and SDS, respectively, while the corresponding decay times at 360 nm are 2.5 ( 0.1 ns and 1.8 ( 0.1 ns.

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Section: Methodssupporting

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Steady-state Emission Spectramentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Excited-State Proton Transfer of 1-Naphthol in Micelles

1998

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“…In this picture the excited state proton transfer dynamics, controlled by barrier crossing, is described by a two-state model (Figure 1 a), where an optically excited photoacid state converts into an excited conjugated photobase upon proton transfer. [16][17][18][19][20][21][22][23][24][25][26] A second model invokes the occurrence of and the internal conversion between nearby lying electronic excited levels of the photoacid (Figure 1 b). Typically two spectroscopically accessible states can be reached for aromatic molecules upon electronic excitation, either with light polarized along the through-bond axis ( 1 L b state) or along the through-atom axis…”

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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UV‐Visible Spectra and Photoacidity of Phenols, Naphthols and Pyrenols

Pines

2009

Patai's Chemistry of Functional Groups

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Introduction The Thermodynamic Aspects of Photoacidity On the Origin of Photoacidity The Electronic Structure of Photoacids Free‐Energy Correlations Between Photoacidity and Reactivity Concluding Remarks: Evaluation of our Current Understanding of the Photoacidity of Hydroxyarenes

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Hydration dynamics of protons from photon initiated acids

Cited by 129 publications

References 1 publication

Excited-State Proton Transfer of 1-Naphthol in Micelles

Excited-State Proton Transfer of 1-Naphthol in Micelles

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

UV‐Visible Spectra and Photoacidity of Phenols, Naphthols and Pyrenols

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