Pressure tuning of solvent viscosity for the formation of twisted intramolecular charge-transfer state in 4,4′-diaminodiphenyl sulfone in alcohol solution

Hara, Kimihiko; Bulgarevich, Dmitry S.; Kajimoto, Okitsugu

doi:10.1063/1.471687

Cited by 14 publications

(14 citation statements)

References 31 publications

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“…Hara et al . [ 80 ] found triple-exponential decay functions when they applied pressure to the solvents to cause a pressure-induced viscosity increase. The analysis of lifetime experiments is complex, because many levels of solvent-rotor interaction, such as diffusion, electrostatic and polar interaction, and hydrogen bonding influence the lifetime dynamics and lead to complex decay patterns.…”

Section: Engineering Aspects Of Molecular Viscometersmentioning

confidence: 99%

Environment-sensitive behavior of fluorescent molecular rotors

2010

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Molecular rotors are a group of fluorescent molecules that form twisted intramolecular charge transfer (TICT) states upon photoexcitation. When intramolecular twisting occurs, the molecular rotor returns to the ground state either by emission of a red-shifted emission band or by nonradiative relaxation. The emission properties are strongly solvent-dependent, and the solvent viscosity is the primary determinant of the fluorescent quantum yield from the planar (non-twisted) conformation. This viscosity-sensitive behavior gives rise to applications in, for example, fluid mechanics, polymer chemistry, cell physiology, and the food sciences. However, the relationship between bulk viscosity and the molecular-scale interaction of a molecular rotor with its environment are not fully understood. This review presents the pertinent theories of the rotor-solvent interaction on the molecular level and how this interaction leads to the viscosity-sensitive behavior. Furthermore, current applications of molecular rotors as microviscosity sensors are reviewed, and engineering aspects are presented on how measurement accuracy and precision can be improved.

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Section: Engineering Aspects Of Molecular Viscometersmentioning

confidence: 99%

Environment-sensitive behavior of fluorescent molecular rotors

2010

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“…The effects of hydrostatic pressure upon chemical and biological reactions and equilibria have been extensively investigated, and considerable amounts of data on the activation and reaction volumes have been compiled. − Apart from these ground-state reactions and equilibria, several photophysical and photochemical processes have recently been subjected to pressure-dependence studies. ,− Thus, the effects of applied pressure and accompanying viscosity change upon fluorescence, − excimer/exciplex formation, − photosubstitution, , photoisomerization, ,− and photocycloaddition 44-47 have been studied in considerable detail. In the photocycloaddition reactions, − the product's regio- or diastereoselectivity has been shown to be more or less dependent upon the applied pressure.…”

Section: Introductionmentioning

confidence: 99%

Pressure and Temperature Control of Product Chirality in Asymmetric Photochemistry. Enantiodifferentiating Photoisomerization of Cyclooctene Sensitized by Chiral Benzenepolycarboxylates

1998

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Pressure effects upon asymmetric photosensitization have been investigated for the first time in the enantiodifferentiating Z − E photoisomerization of cyclooctene (1), sensitized by chiral aromatic esters (2−7). The product's enantiomeric excess (ee) and E/Z ratio were critical functions of the applied pressure, exhibiting an unprecedented switching of the product chirality. Depending upon the chiral sensitizer employed, the differential activation volume (ΔΔV ⧧) varies widely from −3.7 to +5.6 cm3 mol-1, which is unexpectedly large for an enantiodifferentiation in the excited state. However, the ΔΔV ⧧ values obtained do not correlate with the differential activation enthalpy (ΔΔH ⧧) or entropy (ΔΔS ⧧) obtained from temperature-dependence studies, indicating that pressure and temperature function as independent perturbants for the photoenantiodifferentiation process. Further investigations on the pressure dependence of ee at low temperatures enable us to construct the first three-dimensional diagram that correlates the product's ee with pressure and temperature changes. The combined effects of temperature and pressure provide us with a versatile tool for the multidimensional control of asymmetric photochemical reactions, in which we can switch and/or enhance the product chirality at more readily accessible temperatures and pressures, without using antipodal sensitizers.

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“…Therefore, we can conclude that with increasing solvent viscosity by application of pressure, the reaction path shifts from the solvation−controlled scheme to the path controlled by intramolecular vibrational motion. It is this behavior that has been called as “pressure tuning effect” of the solvent viscosity, which has previously been described for the TICT formation of DAPS …”

Section: Resultsmentioning

confidence: 79%

“…In order to understand further the role of solvent dynamics in the ICT reaction of DMATP, the accurate time scale of solvent relaxation at high pressure is needed. In the discussions of the previous papers, , the longitudinal relaxation time (τ L ), which is provided by a dielectric continuum model, has been used to gauge the solvent dynamics pertinent to ICT reactions. However, there is a question whether τ L actually denotes the real time-scale for solvent relaxation.…”

Section: Introductionmentioning

confidence: 99%

“…6 We have used the high-pressure method to change the solvent viscosity and verified the viscosity dependence of various TICT state forming reactions. [7][8][9] The application of high pressure causes a change in solvent viscosity greatly and continuously in a single solvent without altering the solvation structure to any significant extent.…”

Section: Introductionmentioning

confidence: 99%

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Pressure Tuning of Solvent Relaxation Time for the Excited Intramolecular Charge-Transfer Kinetics in 4-(N,N-Dimethylamino)triphenylphosphine in Alcohol

1997

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The dynamic solvent effect on the excited state intramolecular charge-transfer (ICT) reaction of 4-(N,N-dimethylamino)triphenylphosphine (DMATP) in alcohol solvents is examined by a high-pressure method. In order to deduce the solvation effect on the ICT reaction of DMATP, the picosecond time-dependent Stokes shift (TDSS) of coumarin 153 (C153) in alcohols is measured as a function of pressure. The resulting high-pressure solvent relaxation time (τs) is in excellent agreement with the longest longitudinal relaxation time (τL) of alcohols from low-temperature sources. In the low-viscosity region at low pressures, the rate of the ICT formation correlates with τs (or τL), while in the high viscosity region at high pressures, it becomes noticeably faster than τs (or τL).

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Pressure tuning of solvent viscosity for the formation of twisted intramolecular charge-transfer state in 4,4′-diaminodiphenyl sulfone in alcohol solution

Abstract: Ultrafast intramolecular charge transfer and dual fluorescence of dimethylaminosubstituted triphenylphosphines in polar solvents AIP Conf. Solvent controlled ultrafast intramolecular charge transfer and internal rotation AIP Conf.

Cited by 14 publications

References 31 publications

Environment-sensitive behavior of fluorescent molecular rotors

Environment-sensitive behavior of fluorescent molecular rotors

Pressure and Temperature Control of Product Chirality in Asymmetric Photochemistry. Enantiodifferentiating Photoisomerization of Cyclooctene Sensitized by Chiral Benzenepolycarboxylates

Pressure Tuning of Solvent Relaxation Time for the Excited Intramolecular Charge-Transfer Kinetics in 4-(N,N-Dimethylamino)triphenylphosphine in Alcohol

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