Temperature Dependence of the Excited-State Proton-Transfer Reaction of Quinone-cyanine-7

Simkovitch, Ron; Shomer, Shay; Gepshtein, Rinat; Shabat, Doron; Huppert, Dan

doi:10.1021/jp3128669

Cited by 19 publications

(15 citation statements)

References 43 publications

(61 reference statements)

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“…19 In comparison, it is about 10 kJ mol À1 for the differently structured quinine cyanine 7 (QCy7) photoacid in ice (pK a * E À6). 68 All of the above suggest, but do not prove, that at room temperature the family set of proton transfer reactions under our considerations likely belongs to the proton adiabatic limit. However, one may also use the general form of eqn (6) which describes the proton transfer rate in the proton NA tunneling limit for the free-energy correlation of the kinetic data as well.…”

Section: Alternative Modelsmentioning

confidence: 58%

Solvent dependence of excited-state proton transfer from pyranine-derived photoacids

Spies

Shomer

Finkler

et al. 2014

Phys. Chem. Chem. Phys.

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Steady-state and time-resolved techniques were employed to study the excited-state proton-transfer (ESPT) rate of two newly synthesized 8-hydroxy-1,3,6-pyrenetrisulfonate (pyranine, HPTS) derived photoacids in three protic solvents, water, methanol and ethanol. The ESPT rate constant k(PT) of tris(1,1,1,3,3,3-hexafluoropropan-2-yl)-8-hydroxypyrene-1,3,6-trisulfonate, 1a, whose pK(a)* ~ -4, in water, methanol and ethanol is 3 × 10(11) s(-1), 8 × 10(9) s(-1) and 5 × 10(9) s(-1) respectively. (8-Hydroxy-N1,N3,N6-tris(2-hydroxyethyl)-N1,N3,N6-trimethylpyrene-1,3,6 trisulfonamide, 1b) is a weaker acid than 1a but still a strong photoacid with pK(a)* ~ -1 and the ESPT rate in water, methanol and ethanol is 7 × 10(10) s(-1), 4 × 10(8) s(-1) and 2 × 10(8) s(-1). We qualitatively explain our kinetic results by a Marcus-like free-energy correlation which was found to have a general form suitable for describing proton transfer reactions in both the proton-adiabatic and the proton-non-adiabatic limits.

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Section: Alternative Modelsmentioning

confidence: 58%

Solvent dependence of excited-state proton transfer from pyranine-derived photoacids

Spies

Shomer

Finkler

et al. 2014

Phys. Chem. Chem. Phys.

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“…There are many photochemical materials in which, for instance, the rates of light induced reactions are strongly dependent on temperature (e.g. [29]). These reactions in most cases deactivate the material through radiationless paths, that is, they lead to the heating of the sample.…”

Section: Macroscopic Aperture Thermal Lensmentioning

confidence: 99%

Thermal lens in a liquid sample with focal length controllable by bulk temperature

et al. 2016

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In this paper, we propose a new solution, which is an improvement to recent propositions given in [9][10][11]. In contrast to many of the above-cited ideas, which rely on modification of the lens shape, one can induce a refractive index distribution, ∇n, that acts as a lens, without changing the shape of the lensing element. Optical elements with such n distribution, called GRIN (gradient refractive index), are e.g. lenses or fibres, but these elements have ∇n fixed. Therefore, they do not conform to the idea of flexible optical elements (as used e.g. in adaptive optics). Meanwhile, such ∇n can be induced thermally, by irradiation of the thermal lensing element by a heating laser beam, absorbed by this elements material, or by controlled electrical heating of the thermal lensing element [12]. As shown by the authors of Refs. [9][10][11], ∇n formation can lead to the formation of a few millimetre (thus macroscopic)-size aperture thermal lenses whose focal length depends on the heating laser intensity. However, the authors of these two works did not take into account that ∇n at a selected heating laser intensity can depend as well on the bulk temperature of the thermal lens element, irrespective of this element being a liquid [9, 10] or solid [11]. This particular dependence was the subject of our interest, and this work presents the results of our studies.In principle, the laser can also induce the nonlinear Kerr effect or electrostriction force-both of which can lead to nonzero ∇n [13]. In this work, we assume these effects negligible and we focus only on the thermo-optical effect. It follows from nonzero thermo-optical ∂n ∂T parameter of the medium illuminated by heating laser. We present results for a liquid thermal lens material, but thermal lenses can be formed in solids as well, e.g. in glasses. This last case is more attractive from the application point of view. Solids are free from convection and easier to use in different optical set-ups. Additionally, due to the thermal expansion, Abstract An experimental and numerical investigation of the applicability of the temperature-controlled focal length of a thermally induced lens is reported. The thermal lens is formed as a result of absorption of a heating laser beam. Numerical simulations and experimental results show that changing the bulk temperature of the material of the lensing element allows for the selection of its focal length. The range of focal length changes for an example lens is given.

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“…As indicated above, the FCS is expected to have different solution properties from the bulk even at the same ionic strength and temperature. , Although ESPT was studied in the frozen state, no attention was paid to the FCS; − probe molecules were assumed to stay between the ice crystal grains in most studies. Herein, 6-cyano-2-naphthol (6CN) was studied in a FCS based on fluorescence spectroscopy and lifetime measurements.…”

Section: Introductionmentioning

confidence: 99%

Ice Confinement-Induced Solubilization and Aggregation of Cyanonaphthol Revealed by Fluorescence Spectroscopy and Lifetime Measurements

et al. 2020

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When an aqueous salt solution freezes, a freezeconcentrated solution (FCS) separates from the ice. The properties of the FCS may differ from those of a supercooled bulk solution of the same ionic strength at the same temperature. The fluorescence and lifetime characteristics of 6-cyano-2-naphthol (6CN) were studied in frozen NaCl solutions in order to provide insight into the solution properties of the FCS. While the photoacidity of 6CN in an FCS is similar to that in solution, several anomalous behaviors are observed. Fluorescence spectra indicate that the solubility of 6CN is significantly enhanced in the FCS (50 mM or higher) compared to that in the bulk NaCl solution where the solubility limit is 250 μM. The high solubility induces the aggregation of 6CN in the FCS, which is not detected in bulk solutions. This trend becomes marked as the initial NaCl concentration decreases and the FCS is confined in a small space. The fluorescence lifetimes of 6CN in the FCS support the spectroscopy results. In addition to the species identified by fluorescence spectroscopy, excimers are assigned from lifetime measurements in the FCS. The excimer formation is also a result of the enhanced solubility of 6CN in the FCS.

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Temperature Dependence of the Excited-State Proton-Transfer Reaction of Quinone-cyanine-7

Cited by 19 publications

References 43 publications

Solvent dependence of excited-state proton transfer from pyranine-derived photoacids

Solvent dependence of excited-state proton transfer from pyranine-derived photoacids

Thermal lens in a liquid sample with focal length controllable by bulk temperature

Ice Confinement-Induced Solubilization and Aggregation of Cyanonaphthol Revealed by Fluorescence Spectroscopy and Lifetime Measurements

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