The Effect of Solvent on the Acid-Base Kinetics of the Excited State of β-Naphthol<sup>1</sup>

Trieff, Norman M.; Sundheim, Benson R.

doi:10.1021/j100890a041

Cited by 54 publications

(27 citation statements)

References 1 publication

(2 reference statements)

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“…These larger shifts in S 1 correspond to the increase of the acidity of 2NpOH in S 1 ; pK a ) 3.0 in the S 1 state while pK a ) 9.45 in the S 0 state. 15,16 Thus, OH bond strength is more weakened in S 1 by the stronger hydrogen bond than in S 0 .…”

Section: Resultsmentioning

confidence: 99%

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters

2001

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IR spectra of the OH stretching vibrations of 2-naphthol-B (B ) H 2 O and CH 3 OH) clusters in S 1 have been measured by photofragment detected IR spectroscopy (PFDIRS). In this spectroscopy, a tunable IR light pulse excites the OH stretching vibration of the electronically excited 2-naphthol-B, which is prepared by a UV light pulse. The vibrationally excited cluster immediately predissociates to generate a 2-naphthol fragment in S 1 . By monitoring the emission only from the 0 0 0 band of the fragment with a monochromator while scanning the IR frequency, a background free IR spectrum of the OH stretching vibration of the cluster in S 1 has been successfully obtained. By comparing the IR spectra of the cluster in S 1 with those of in S 0 , the effect of the electronic excitation on the frequency change of the OH stretching vibration in the cluster is discussed.

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Section: Resultsmentioning

confidence: 99%

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters

2001

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“…Calculations of rates of excited-state proton transfer have previously been made using steady-state techniques (Weller, 1952(Weller, , 1961Trieff and Sundheim, 1965). In this method the relative quantum yields of the protonated and ionized species are determined as a function of pH.…”

Section: Resultsmentioning

confidence: 99%

“…The 2,6-naphtholsulfonate-bovine serum albumin complex does demonstrate the dramatic change which can be observed when the environment of such a dye is changed. Since rates of excited-state proton transfer depend on the character of the solvent as well as on the nature of the proton acceptor (Stryer, 1966;Trieff and Sundheim, 1965;Deluca et al, 1971), localized changes in these parameters which occur when a macromolecule undergoes conformational change may be reflected by changes in these rates. Fluorescent probes which undergo excited-state ionization can thus be used both for the characterization of their microenvironments and as sensitive detectors of conformational changes.…”

Section: Resultsmentioning

confidence: 99%

Excited-state proton transfer as a biological probe. Determination of rate constants by means of nanosecond fluorometry

Loken¹,

Hayes²,

Gohlke³

et al. 1972

Biochemistry

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Ionization constants of organic acids in the excited state may differ by several orders of magnitude from those observed in the ground state (Weller, A. (1961), Progr. React. Kinet. 1, 187). Nanosecond time-resolved fluorescence spectroscopy has been used to detect proton transfer in the excited state. It is shown that fluorescence lifetime data can be used to obtain the rate constants for excited-state proton transfer of 2-naphthol in aqueous solution. Three distinct methods are described for the calculation of rate constants, and good agree-D ifferences in the chemical and physical properties of molecules in their excited states relative to their ground states can be used as the basis for designing probes of biological microenvironments. Organic acids exhibit excited-state ionization constants which differ by several orders of magnitude from those observed in the ground state (Forster, 1950a;Weller, 1961;Wehry and Rogers, 1966; Vander Donckt, 1970). Weller (1952), as well as other workers, has used steadystate fluorescence methods to calculate the forward and reverse rate constants for proton transfer. Rate constants for proton transfer depend on solvent environment and on the character of proton donors and acceptors. A quantitative measure of the environment of the probe can be made by calculating rates of proton transfer. These rates are expected to be sensitive to changes in protein conformation.Quantitation of rate constants using kinetic methods yields the same values as those obtained by steady-state techniques using model compounds such as 2-naphthol. However, more information about the reacting system can be obtained by analysis of fluorescence decay curves, and such analysis can be applied to fluorescent probes attached to proteins. In this approach, light absorption and fluorescence are used as a relaxation technique to study reactions on a time scale of sec or less. This type of relaxation technique differs from the traditional relaxation techniques in the extent of the perturbation. In excited-state studies the equilibrium is shifted by converting the reaction partners to new species (the excited state) rather than by changing intensive parameters such as the temperature or pressure.Previous work (DeLuca et al., 1971 ;Bowie et al., 1972) has demonstrated the potential of excited-state proton transfer for investigating the active sites of enzymes. The aim of the present ment is obtained between the values for rate constants ob. tained by these methods and those obtained with the steadystate approach. Rapid rates of excited-state proton transfer are found with 2,6-naphtholsulfonate in aqueous solution. When this chromophore is adsorbed to bovine serum albumin, little or no proton transfer is observed. The potential application of excited-state proton transfer to studies of biological macromolecules is discussed.paper is to show how rate constants for excited-state proton transfer can be obtained from fluorescence lifetime measurements and to indicate the advantage of this approach over steady-state m...

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“…5 When a base is added to the solution, direct PT by the mechanism of eq 1 is expected to compete with PT to solvent. [6][7][8][9] To obtain a good estimate of k 0 , independent of PT to the solvent and diffusion, the reaction was investigated at very high base concentrations (8 M). 10 When the acid-base reaction is sufficiently downhill to be irreversible and the base is in large excess (pseudounimolecular conditions), the mechanism in eq 1 leads to Smoluchowski kinetics.…”

Section: Introductionmentioning

confidence: 99%

Distance-Dependent Proton Transfer along Water Wires Connecting Acid−Base Pairs

et al. 2009

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We report time-resolved mid-IR kinetics for the ultrafast acid-base reaction between photoexcited 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), and acetate at three concentrations (0.5, 1.0, and 2.0 M) and three temperatures (5, 30, and 65 degrees C) in liquid D(2)O. The observed proton-transfer kinetics agree quantitatively, over all times (200 fs-500 ps), with an extended Smoluchowski model which includes distance-dependent reactivity in the form of a Gaussian rate function, k(r). This distance dependence contrasts with the exponential k(r) that is typically observed for electron-transfer reactions. The width of k(r) is essentially the only parameter varied in fitting the proton-transfer kinetics at each concentration and temperature. We find that k(r) likely represents the rate of concerted (multi)proton hopping across "proton wires" of different length r that connect acid-base pairs in solution. The concerted nature of the proton transfer is supported by the fact that k(r) shows a steeper dependence on r at higher temperatures.

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The Effect of Solvent on the Acid-Base Kinetics of the Excited State of β-Naphthol¹

Cited by 54 publications

References 1 publication

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters

Excited-state proton transfer as a biological probe. Determination of rate constants by means of nanosecond fluorometry

Distance-Dependent Proton Transfer along Water Wires Connecting Acid−Base Pairs

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The Effect of Solvent on the Acid-Base Kinetics of the Excited State of β-Naphthol1

Cited by 54 publications

References 1 publication

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S1 StateApplication to 2-Naphthol-B (B = H2O and CH3OH) Clusters

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S1 StateApplication to 2-Naphthol-B (B = H2O and CH3OH) Clusters

Excited-state proton transfer as a biological probe. Determination of rate constants by means of nanosecond fluorometry

Distance-Dependent Proton Transfer along Water Wires Connecting Acid−Base Pairs

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The Effect of Solvent on the Acid-Base Kinetics of the Excited State of β-Naphthol¹

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters

Photofragment-Detected IR Spectroscopy (PFDIRS) for the OH Stretching Vibration of the Hydrogen-Bonded Clusters in the S₁ StateApplication to 2-Naphthol-B (B = H₂O and CH₃OH) Clusters