Phase-Transfer Catalysis

Starks, Charles M.; Liotta, Charles L.; Halpern, Marc

doi:10.1007/978-94-011-0687-0

Cited by 536 publications

(235 citation statements)

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“…If one follows individual trajectories, it can be seen that some of the crowns (see e.g. d 9 and d 4 ) first moved away from the interface (about 10 Å), but then returned closer (about 5 Å). They remained D 3d and coordinated to water molecules.…”

Section: Distribution With Respect To the Interfacementioning

confidence: 99%

Interfacial Behavior of Ionophoric Systems: Molecular Dynamics Studies on 18-Crown-6 and Its Complexes at the Water-Chloroform Interface

Troxler

Wipff

1998

ANAL. SCI.

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Section: Distribution With Respect To the Interfacementioning

confidence: 99%

Interfacial Behavior of Ionophoric Systems: Molecular Dynamics Studies on 18-Crown-6 and Its Complexes at the Water-Chloroform Interface

Troxler

Wipff

1998

ANAL. SCI.

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“…Understanding electron transfer (ET) at the interface between two immiscible electrolyte solutions (IES) is of fundamental importance in electrochemistry, [1][2][3][4][5][6][7] solar energy conversion and "artificial photosynthesis," [8][9] and phase transfer catalysis, [10][11][12] and may also be relevant to understanding biological processes at membrane interfaces and in DNA environments. 13 The experimental study of ET at IES has a long history, 2 but up until recently, measurements of electron transfer rates have mainly utilized conventional electrochemical methods, where the interface was under potentiostatic control.…”

Section: Introductionmentioning

confidence: 99%

Photoinduced Excited State Electron Transfer at Liquid/Liquid Interfaces

Cooper

Benjamin

2014

J. Phys. Chem. B

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Abstract:Several aspects of the photoinduced electron transfer (ET) reaction between coumarin 314 (C314) and N,N-dimethylaniline (DMA) at the water/DMA interface are investigated by molecular dynamics simulations. New DMA and water/DMA potential energy surfaces are developed and used to characterize the neat water/DMA interface.The adsorption free energy, the rotational dynamics and the solvation dynamics of C314 at the liquid/liquid interface are investigated and are generally in reasonable agreement with available experimental data. The solvent free energy curves for the ET reaction between excited C314 and DMA molecules are calculated and compared with those calculated for a simple point charge model of the solute. It is found that the reorganization free energy is very small when the full molecular description of the solute is taken into account. An estimate of the ET rate constant is in reasonable agreement with experiment. Our calculations suggest that the polarity of the surface "reported" by the solute, as reflected by solvation dynamics and the reorganization free energy, is strongly solute-dependent.

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“…43 Phase transfer catalysts, which facilitate movement of a reactant from an aqueous phase to organic medium, have had tremendous impact in the field of organic synthesis; these agents accelerate reaction rates, make possible heterogeneous chemical reactions, and minimize solvent waste. 52 PNES is insoluble in all common organic solvents. Addition of the phase transfer catalyst 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) to organic solvents enables PNES Na + complexation and solvation and polymer dissolution.…”

mentioning

confidence: 99%

Phase Transfer Catalysts Drive Diverse Organic Solvent Solubility of Single-Walled Carbon Nanotubes Helically Wrapped by Ionic, Semiconducting Polymers

et al. 2010

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Use of phase transfer catalysts such as 18-crown-6 enables ionic, linear conjugated poly[2,6-{1,5-bis(3-propoxysulfonicacidsodiumsalt)}naphthylene]ethynylene (PNES) to efficiently disperse single-walled carbon nanotubes (SWNTs) in multiple organic solvents under standard ultrasonication methods. Steady-state electronic absorption spectroscopy, atomic force microscopy (AFM), and transmission electron microscopy (TEM) reveal that these SWNT suspensions are composed almost exclusively of individualized tubes. High-resolution TEM and AFM data show that the interaction of PNES with SWNTs in both protic and aprotic organic solvents provides a self-assembled superstructure in which a PNES monolayer helically wraps the nanotube surface with periodic and constant morphology (observed helical pitch length ) 10 ( 2 nm); time-dependent examination of these suspensions indicates that these structures persist in solution over periods that span at least several months. Pump-probe transient absorption spectroscopy reveals that the excited state lifetimes and exciton binding energies of these well-defined nanotube-semiconducting polymer hybrid structures remain unchanged relative to analogous benchmark data acquired previously for standard sodium dodecylsulfate (SDS)-SWNT suspensions, regardless of solvent. These results demonstrate that the use of phase transfer catalysts with ionic semiconducting polymers that helically wrap SWNTs provide well-defined structures that solubulize SWNTs in a wide range of organic solvents while preserving critical nanotube semiconducting and conducting properties.KEYWORDS Single chain, helical wrapping, ionic poly(aryleneethynylene), phase transfer catalyst, SWNTs, organic solvent S ingle wall carbon nanotubes (SWNTs) 1-4 possess a wide range of uncommon mechanical, 5-9 optical, 1,10-12 electrical, 13-17 magnetic, 18-21 and thermal 22,23 properties that fuel multidisciplinary efforts aimed at developing neoteric nanoscale, microscale, and bulkphase materials. 2 Strong van der Waals interactions between SWNTs 24,25 are an anathema to SWNT solubilization. 13 Water-solubilized SWNTs dominate the literature; there exists no general method to disperse SWNTs in nonaqueous media. Potential dispersion approaches are truncated severely by the fact that preservation of significant SWNT electrooptic properties require solubilization via agents that noncovalently interact with the nanotube surface. 24,25 It has thus been a long-standing goal to develop a universal SWNT solubilization strategy that (i) relies on noncovalent interactions for nanotube dispersion, (ii) provides a high yield of individualized tubes, (iii) enables dispersion in a wide range of dielectric media, and yet (iv) gives rise to suspended SWNT structures having a constant morphology, regardless of solvent.Ultrasonication 11,26 and high-speed vibrational milling techniques 27 are commonly utilized to drive exfoliation of nanotube ropes and bundles in the presence of surfactants, small molecules, and polymers. 28 The huge library o...

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Phase-Transfer Catalysis

Cited by 536 publications

References 0 publications

Interfacial Behavior of Ionophoric Systems: Molecular Dynamics Studies on 18-Crown-6 and Its Complexes at the Water-Chloroform Interface

Interfacial Behavior of Ionophoric Systems: Molecular Dynamics Studies on 18-Crown-6 and Its Complexes at the Water-Chloroform Interface

Photoinduced Excited State Electron Transfer at Liquid/Liquid Interfaces

Phase Transfer Catalysts Drive Diverse Organic Solvent Solubility of Single-Walled Carbon Nanotubes Helically Wrapped by Ionic, Semiconducting Polymers

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