Resonant-surface second-harmonic generation studies of phenol derivatives at air/water and hexane/water interfaces

Tamburello-Luca, Alfio A.; Hébert, Philippe; Brevet, P. F.; Girault, Hubert H.

doi:10.1039/ft9969203079

Cited by 52 publications

(74 citation statements)

References 29 publications

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“…Despite the weakness of the SH signals, the technique has allowed to probe liquid interfaces with a detailed insight into molecular properties. [7±9] At liquid/ liquid interfaces, orientation, solvation, and chemical equilibria have been studied [10,11] and polarised interfaces have also been investigated. [12,13] Furthermore, an interfacial polarity scale has been established for a wide range of liquid interfaces with solvatochromic probes.…”

Section: Introductionmentioning

confidence: 99%

Intramolecular Electron Density Redistribution upon Hydrogen Bond Formation in the Anion Methyl Orange at the Water/1,2-Dichloroethane Interface Probed by Phase Interference Second Harmonic Generation

et al. 2000

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Surface second harmonic generation (SSHG) studies of the azobenzene derivative p-dimethylaminoazobenzene sulfonate, often referred as Methyl Orange (MO), at the neat water/1,2-dichloroethane (DCE) interface is reported. The two forms of the anionic MO dye, which are usually observed in bulk solution, with one form being hydrogen bonded to a water molecule through the azo nitrogens (MO/H2O) and the other form not being hydrogen bonded (MO) have also been observed at the water/DCE interface. Their equilibrium constant has been compared with the corresponding bulk solution and found to be identical. The adsorption equilibrium of the two forms has been determined and the Gibbs energy of adsorption measured to be -30 kJmol(-1) for both forms. From a light polarisation analysis of the SH signal, the angle of orientation of the MO transition dipole moment was found to be 34 +/- 2 degrees for MO and 43 +/- 2 degrees for MO/H2O under the assumption of a Dirac delta function for the angle distribution, a difference explained by the different solvation properties of the two forms. Furthermore, the wavelength dependence analysis of these data revealed an interference pattern resulting from the electronic density redistribution within the hydrated anionic form occurring upon the formation of the hydrogen bond with a water molecule. This interference pattern was clearly evidenced with the use of another dye at the interface in order to define a phase reference to both forms of Methyl Orange.

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Section: Introductionmentioning

confidence: 99%

Intramolecular Electron Density Redistribution upon Hydrogen Bond Formation in the Anion Methyl Orange at the Water/1,2-Dichloroethane Interface Probed by Phase Interference Second Harmonic Generation

et al. 2000

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“…From the surface tension data at pH 1 and pH 13 the corresponding surface excess was calculated based on the Gibbs equation [12]. The stronger proclivity of phenol to the air/water interface [43,44] is seen in the larger adsorption equilibrium constant, K phenol ads , of phenol, 682 ± 69, at a bulk pH of 1, compared with phenolate K phenolate ads of 24 ± 3 at a bulk pH of 13. Comparison of the adsorption equilibrium constants shows that phenol, being neutral, is more surface active, by a factor of 28 with respect to phenolate.…”

Section: The Importance Of Maintaining a Constant Phmentioning

confidence: 99%

Organic ions at the air/water interface

Rao

Subir

McArthur

et al. 2009

Chemical Physics Letters

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“…2À5,14,45À53 An important point to note is that the nonresonant contribution to the second-order susceptibility is intrinsic to all interfacial systems and can lead to asymmetry in resonance enhanced line shapes. Depending on its magnitude and sign, χ NR (2) can result in calculated excitation wavelengths that differ noticeably from the experimentally measured λ max . Because χ NR (2) can be different for each type of interface studied, this term was treated simply as an adjustable parameter.…”

Section: ' Introductionmentioning

confidence: 86%

Effects of Solvent Structure on Interfacial Polarity at Strongly Associating Silica/Alcohol Interfaces

Siler

Walker

2011

J. Phys. Chem. C

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b S Supporting Information ' INTRODUCTIONInterfacial solvation will depend sensitively on a subtle balance of soluteÀsubstrate, soluteÀsolvent, and substrateÀsolvent interactions. Here, the term solvation is used to describe the local environment experienced by a solute. Interfacial solvation has often been described in terms of averaged contributions from the two adjacent phases. 1À6 Such models have proven successful at describing solvation across weakly associating interfaces characterized by large excess free energies. When experimental findings differ from predictions of this "averaged" model of interfacial solvation, results can usually be rationalized in terms of complex solvent structure that reorganizes under the constraint of reduced mobility and strong, directional forces imposed by the surface. 1,5,7À13 These interphase substrateÀsolvent interactions form local domains having properties that do not arise in bulk solution. Only recently have researchers begun to report how more subtle effects such as solute orientation and solute solubility in bulk solution can influence interfacial solvation. 9,14À19 Strongly associating solid/liquid interfaces are characterized by low interfacial energies and strong, directional interactions between the substrate and the solvent. These forces impose longrange structure on the adjacent solvent that can extend several solvent diameters into bulk solution. 17,20À24 The effects of solid surfaces on solvent structure remain an area of active investigation. Fundamental studies attempt to isolate and quantify asymmetric, intermolecular interactions, while empirical investigations parametrize interphase forces between solid substrates and different solvent mixtures to improve chromatographic separations and to tune surface reactivity. 25À33 The affinitiy of a solute for a surface strongly influences adsorption energetics and the resulting environment that a solute samples. In the case of strong soluteÀsubstrate associations, solvent identity may not play a significant role in interfacial solvation. However, if solventÀsubstrate interactions are significantly stronger than those between the solute and substrate, then solute molecules might not accumulate at an interface at all. An example of how these competing energetics affect interfacial phenomena comes from detailed studies of adsorption and retention in chromatographic systems. Wirth and co-workers reported tailing and line broadening in model liquid chromatography measurements and assigned this effect to strong associations between solutes and the silica substrates. 29 They noted that this behavior occurs at both low and neutral pH values with neutral pH values leading to longer retention times and more broadening. Rendering the mobile phase acidic reduces retention time but still results in eluent tailing due to strong adsorption sites on the silica composed of acidic ABSTRACT: Resonance-enhanced second harmonic generation (SHG) spectroscopy was used to probe the electronic structure of p-nitroanisole (pNAs) adsorbed...

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Resonant-surface second-harmonic generation studies of phenol derivatives at air/water and hexane/water interfaces

Cited by 52 publications

References 29 publications

Intramolecular Electron Density Redistribution upon Hydrogen Bond Formation in the Anion Methyl Orange at the Water/1,2-Dichloroethane Interface Probed by Phase Interference Second Harmonic Generation

Intramolecular Electron Density Redistribution upon Hydrogen Bond Formation in the Anion Methyl Orange at the Water/1,2-Dichloroethane Interface Probed by Phase Interference Second Harmonic Generation

Organic ions at the air/water interface

Effects of Solvent Structure on Interfacial Polarity at Strongly Associating Silica/Alcohol Interfaces

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