Primary ultrafast events preceding the photoinduced proton transfer from pyranine to water

Tran‐Thi, T.‐H.; Gustavsson, T.; Prayer, C.; Pommeret, S.; Hynes, James T.

doi:10.1016/s0009-2614(00)01037-x

Cited by 198 publications

(274 citation statements)

References 27 publications

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“…Based on these findings we cannot support but also not exclude a nonadiabatic electronic state change in MPTS and in HPTS photoacid, from LE( 1 L b ) to CT( 1 L a ) as proposed by TranThi et al [40,41] This change may indeed occur in water, but not on a time scale of 2 ps. The dynamics of the electronic excited states on the 2 ps time scale as found with UV-pump/Visprobe spectroscopy are unlikely due to electronic state level crossing, but supposedly caused by solvation dynamics of the solvent.…”

Section: Solvent-dependent Electronic States In Pyraninementioning

confidence: 57%

“…A mechanistic view of such a solvent mediated level structure of HPTS has been considered by Tran-Thi et al. [40,41] In this model a stronger acidity is expected in the CT( 1 L a ) state of HPTS compared to photoacidity of the LE( 1 L b ) state, and a stronger hydrogen bond is consistent with this picture.…”

Section: Transient Vibrational Dynamics Of Mpts and Hpts Photoacids Amentioning

confidence: 77%

“…A solvatochromic study of HPTS in a variety of solvents has been performed where the absorption and emission frequency shifts were interpreted assuming excitation and emission from a single electronic state. [46] In another study of solvatochromic properties of absorption and emission bands of HPTS [41] and the time-resolved UV-pump/Vis-probe study [40] by Thran-Thi et al, the conclusion has been drawn that the observed features can be explained by the three-state LE-CT model, with the LE( 1 L b )!CT( 1 L a ) state inversion taking place with a time constant of about 2 ps. Our approach is to characterise the nature of the excited electronic states by inspection of the associated infrared-active vibrations with time-resolved spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

“…For 1-naphthol [36,37] the 1 L b ! 1 L a transition is considered to be the ESPT-determining step [9,38,39] In contrast, in a recent combined experimental/theoretical study of ESPT of pyranine [40][41][42] the rate determining step is not the conversion from the optically accessible locally excited (LE) state (or alternatively the 1 L b state), to the second photoacid electronic excited n-p* CT state (or 1 L a state), but the transition of the photoacid CT to photobase CT states.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Solvent-dependent Electronic States In Pyraninementioning

confidence: 57%

Section: Transient Vibrational Dynamics Of Mpts and Hpts Photoacids Amentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2005

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“…2). Interestingly, the fluorescence maximum is 515 nm in both acidic and alkaline pH, because the pK a of the excited state molecule is much smaller, leading to fast deprotonation in all but highly acidic environments (25,26). Laser-pulse optimization depends on the characteristics of the laser pulse (central wavelength, spectral phase, and pulse duration) and on multiphoton intrapulse interference (14)(15)(16), which leads to the suppression of twophoton excitation at certain wavelengths.…”

mentioning

confidence: 99%

Use of coherent control methods through scattering biological tissue to achieve functional imaging

Cruz

Pastirk

Comstock

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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We test whether coherent control methods based on ultrashortpulse phase shaping can be applied when the laser light propagates through biological tissue. Our results demonstrate experimentally that the spectral-phase properties of shaped laser pulses optimized to achieve selective two-photon excitation survive as the laser pulses propagate through tissue. This observation is used to obtain functional images based on selective two-photon excitation of a pH-sensitive chromophore in a sample that is placed behind a slice of biological tissue. Our observation of coherent control through scattering tissue suggests possibilities in multiphoton-based imaging and photodynamic therapy.pulse shaping ͉ two-photon ͉ femtosecond laser ͉ intrapulse interference I nterest in coherent laser control has grown steadily, given its potential for influencing quantum-mechanical laser-molecule interactions (1-7). With the use of pulse shapers and computer learning algorithms, scientists have controlled the excitation of isolated atoms and molecules (8-10) and, more recently, large molecules in solution (11-13). Population transfer between different electronic states of large organic molecules can be maximized or minimized through manipulation of the spectral phase of ultrashort laser pulses (14, 15). The benefits of coherent laser control of large organic molecules can be extended to the biological field through selective two-photon chemical microenvironment probing (16) and microscopy (17). Control of lasermatter interactions could revolutionize biomedical applications. Coherent control schemes, for example, could enhance methods such as two-photon imaging (18, 19), which has provided higher resolution, lower background scattering, and better sample penetration than traditional techniques. Selective two-photon excitation would be desirable for distinguishing healthy from cancerous tissue based on differences in their chemical properties, such as pH, or for activating a photodynamic therapy (PDT) agent only when it is absorbed by cancer cells by using twophoton activated PDT (20). These improvements would be possible only if shaped laser pulses maintain their unique properties as they transmit through scattering biological tissue.Coherent control of laser-induced processes is based on the quantum interference among multiple excitation pathways (3). Progress in this field has been fueled by advances in pulseshaping technology, allowing control of the phase and amplitude across the bandwidth of ultrashort laser pulses (21). Control schemes depend on introducing intricate phase structures on the laser pulses that, by means of constructive and͞or destructive interference, optimize the desired outcome and minimize other pathways. This dependence on the accurate phase structure of the pulse suggests that these methods may not be applicable to situations involving transmission through scattering biological tissue.When a laser beam passes through a turbid scattering medium, its coherence (a property of waves defined as the degree with which w...

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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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Primary ultrafast events preceding the photoinduced proton transfer from pyranine to water

Cited by 198 publications

References 27 publications

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

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

Use of coherent control methods through scattering biological tissue to achieve functional imaging

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

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