Proton Antenna Effect of the γ-Cyclodextrin Outer Surface, Measured by Excited State Proton Transfer

Gepshtein, Rinat; Leiderman, Pavel; Huppert, Dan; Elad,; Nachliel, Esther; Gutman, Menachem

doi:10.1021/jp065139w

Cited by 35 publications

(40 citation statements)

References 59 publications

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“…96 However, when pyranine is encapsulated in a cyclodextrin cavity the ESPT exhibits an additional slow component at the B1500 ps time scale. 97,98 Similar retardation is also observed inside a P123-CTAC aggregate. 99 Proton transfer involves primarily three stepsinitial proton transfer, recombination of the ion pair and dissociation of the ion pair.…”

Section: Implications Of Slow Biological Water In Polar Reactionssupporting

confidence: 69%

Nature of biological water: a femtosecond study

2008

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The quasi-bound biological or structured water molecules in a protein play a key role in many biological processes. The dynamics of the biological water has been studied by femtosecond spectroscopy and large-scale computer simulations. Solvation dynamics of biological water displays an almost bulk-water like ultrafast component (approximately 1 ps) and a surprising slow component at the 100-1000 ps time scale. In this article, we discuss several examples of the ultraslow component, its possible origin and implications in biology. We show that the ultrafast (approximately 1 ps) component arises from an extended hydrogen bond network while the ultraslow component originates from binding of a water molecule to a biological macromolecule.

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Section: Implications Of Slow Biological Water In Polar Reactionssupporting

confidence: 69%

Nature of biological water: a femtosecond study

2008

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“…Huppert et al 5 studied ESPT of a similar molecule in AOT microemulsion and considered a diffusion model introduced by Agmon. Most recently, several groups including us applied femtosecond spectroscopy to study ultrafast ESPT of HPTS in other nanoconfined systems such as cyclodextrins [14][15][16][17][18][19] and polymer-surfactant aggregates. 34 They reported that the rate of ESPT increases gradually on addition of water.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast and ultraslow proton transfer of pyranine in an ionic liquid microemulsion

Mojumdar

Mondal

Das

et al. 2010

The Journal of Chemical Physics

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Effect of a room temperature ionic liquid (RTIL) and water on the ultrafast excited state proton transfer (ESPT) of pyranine (8-hydroxypyrene-1,3,6-trisulfonate, HPTS) inside a microemulsion is studied by femtosecond up-conversion. The microemulsion consists of the surfactant, triton X-100 (TX-100) in benzene (bz) and contains the RTIL, 1-pentyl-3-methyl-imidazolium tetrafluoroborate ([pmim] [BF(4)]) as the polar phase. In the absence of water, HPTS undergoes ultrafast ESPT inside the RTIL microemulsion (RTIL/TX-100/bz) and the deprotonated form (RO(-)) exhibits three rise components of 0.3, 14, and 375 ps. It is proposed that in the RTIL microemulsion, HPTS binds to the TX-100 at the interface region and participates in ultrafast ESPT to the oxygen atoms of TX-100. On addition of water an additional slow rise of 2150 ps is observed. Similar long rise component is also observed in water/TX-100/benzene reverse micelle (in the absence of [pmim] [BF(4)]). It is suggested that the added water molecules preferentially concentrate (trapped) around the palisade layer of the RTIL microemulsion. The trapped water molecules remain far from the HPTS both in the presence and absence of ionic liquid and gives rise to the slow component (2150 ps) of ESPT. Replacement of H(2)O by D(2)O causes an increase in the time constant of the ultraslow rise to 2350 ps.

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“…In neat water,t he absorption spectra shows only as ingle prominentp eak at 404 nm, whichi sa ttributed to the protonated form of the dye, and is consistent with previously reported ground-statea bsorption spectra for HPTS in water. [40,57,58] The presence of only one absorption band at all compositions of DMSO/water mixturess uggestst he existence of only the protonated form of HPTS at all compositions.…”

Section: Ground-statea Bsorption Measurementsmentioning

confidence: 99%

Proton Transfer Reaction Dynamics of Pyranine in DMSO/Water Mixtures

Awasthi¹,

Singh

2017

ChemPhysChem

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Photoinduced intermolecular excited-state proton transfer (ESPT) reactions are ubiquitous in chemistry and biology. ESPT reactions are extremely sensitive to the nature of water molecules in its microenvironment and thus serve as a sensitive reporter for the water structure and dynamics in a system. Herein, the photoinduced intermolecular ESPT reaction of 8-hydroxypyrene-1,3,5-trisulfonic acid (HPTS, also known as pyranine) has been investigated in various DMSO/water mixtures by using steady-state and time-resolved emission spectroscopy. The DMSO/water binary mixture yields an interesting and anomalous behavior for the proton transfer reaction dynamics of HPTS at a mole fraction of DMSO (X ) of 0.41-0.51, which has also been previously investigated and projected as an anomalous region by molecular dynamics simulation and other experimental techniques. The extreme slowdown of the proton transfer reaction observed at X =0.41-0.51 has been attributed to the slow solvation dynamics, as well as the non-availability of free water molecules at this composition, which are required to solvate the newly generated proton. These observations have been also corroborated by time-resolved area-normalized emission spectra. The dimensionality of the proton diffusion process has been investigated by analyzing the geminate recombination process, and is found to be significantly different in DMSO/water mixtures (X =0.41-0.51) compared with three-dimensional proton diffusion in neat water.

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Proton Antenna Effect of the γ-Cyclodextrin Outer Surface, Measured by Excited State Proton Transfer

Cited by 35 publications

References 59 publications

Nature of biological water: a femtosecond study

Nature of biological water: a femtosecond study

Ultrafast and ultraslow proton transfer of pyranine in an ionic liquid microemulsion

Proton Transfer Reaction Dynamics of Pyranine in DMSO/Water Mixtures

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