Water at Hydrophobic Surfaces: Weak Hydrogen Bonding and Strong Orientation Effects

Scatena, Lawrence F.; Brown, M. G.; Richmond, Geraldine L.

doi:10.1126/science.1059514

Cited by 986 publications

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“…21,22,23,24,26,27,28,37,70,71,72 Richmond recently reviewed the current understanding of the bonding and energetics, as well as the SFG spectra assignment, of various aqueous interfaces, including the air/water interface. 27,28 The SFG spectral assignments heavily relied on band fitting of IR and Raman peak positions of bulk water or water cluster spectra, 28 as well as based on theoretical calculations.…”

Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

“…24 Richmond et al also suggested that the intensity at about 3450cm −1 include the contribution of donor O-H bond. 26 Recent progresses on SFG-VS have made it possible to determine the symmetry properties of SFG-VS vibrational spectral features through comparison of SFG spectra in different polarizations and experimental configurations. 50,51,52,53 The key idea of this development is from the commonsense of molecular spectroscopy that vibrational modes of molecular groups with different symmetry properties have different polarization dependence on the interacting optical fields.…”

Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

“…Above discussion also throw doubts on the existence of interfacial water molecules with two free O-H bonds, as suggested somewhat less convincingly by some recent studies. 13,17,23,26,71 According to the polarization selection rules and the calculation for the polarization dependence of the C 2v water molecules, no detectable spectral features satisfying the C 2v symmetry in the 3600cm −1 and 3800cm −1 has been observed in the SFG spectra.…”

Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

“…17,20,23,25 With SFG-VS experimental studies, the following interfacial water species have been reported in literatures, namely, water molecules straddle at the interface with one OH bond hydrogen bonded to neighboring molecules in liquid phase (singly bonded OH) and another OH bond free from hydrogen bonding (free OH) in gas phase; 22,23,24,37 water molecules with both OH bonds symmetrically hydrogen bonded in a tetrahedral network (ice-like and liquid-like structures); 22,23,24,37 and water molecules in gas phase with both OH bonds not hydrogen bonded pointing into the liquid phase. 23,26 With NEXAFS measurement and ab initio molecular dynamics simulation, water molecules with both OH bonds not hydrogen bonded pointing out of the interface was also proposed. 13,17 The latter case is particularly controversial because NEXAFS is not strictly a surface specific technique.…”

Section: Introductionmentioning

confidence: 99%

“…Spectroscopy, molecular structure and dynamics at air/water interface is studied with theoretical analysis such as ab initio calculation or molecular dynamics simulation, 5,6,7,8,9,10,11,12,13 or experimental techniques such as X-ray reflection, 14,15 Stimulated Raman Scattering (SRS), 16 Near-edge X-Ray Adsorption Fine Structure (NEXAFS), 17 Second Harmonic Generation (SHG), 18,19 as well as Sum Frequency Generation, etc. 20,21,22,23,24,25,26,27,28 Among these experimental techniques, Second Harmonic Generation and Sum Frequency Generation are the most important methods for molecular interface studies because of their surface sensitivity and specificity. 29,30,31,32,33,34,35,36 With these investigations, the properties of the water molecules at the interface, such as the surface density, surface structure, surface potential as well as surface dynamics, have been intensively discussed.…”

Section: Introductionmentioning

confidence: 99%

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Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

Gan¹,

Wu²,

Zhang³

et al. 2006

The Journal of Chemical Physics

250

332

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Here we report a detailed study on spectroscopy, structure and dynamics of water molecules at air/water interface, investigated with Sum Frequency Generation Vibrational Spectroscopy (SFG-VS). Quantitative polarization and experimental configuration analysis of the SFG data in different polarizations with four sets of experimental configurations can shed new lights on our present understanding of the air/water interface. Firstly, we concluded that the motion of the interfacial water molecules can only be in a limited angular range, instead rapidly varying over a broad angular range in the vibrational relaxation time suggested previously. Secondly, because different vibrational modes of different molecular species at the interface has different symmetry properties, polarization and symmetry analysis of the SFG-VS spectral features can help assignment of the SFG-VS spectra peaks to different interfacial species. These analysis concluded that the narrow 3693cm −1 and broad 3550cm −1 peaks belong to C∞v symmetry, while the broad 3250cm −1 and 3450cm −1 peaks belong to the symmetric stretching modes with C2v symmetry. Thus, the 3693cm −1 peak is assigned to the free OH, the 3550cm −1 peak is assigned to the single hydrogen bonded OH stretching mode, and the 3250cm −1 and 3450cm −1 peaks are assigned to interfacial water molecules as two hydrogen donors for hydrogen bonding (with C2v symmetry), respectively. Thirdly, analysis of the SFG-VS spectra concluded that the singly hydrogen bonded water molecules at the air/water interface have their dipole vector direct almost parallel to the interface, and is with a very narrow orientational distribution. The doubly hydrogen bond donor water molecules have their dipole vector point away from the liquid phase.

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Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

Section: Polarization Analysis and Determination Of Spectral Symmementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

Gan¹,

Wu²,

Zhang³

et al. 2006

The Journal of Chemical Physics

250

332

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Ansätze zur Beschreibung und Vorhersage der Bindungsaffinität niedermolekularer Liganden an makromolekulare Rezeptoren

Gohlke

Klebe

2002

Angew. Chem.

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Der Einfluss einer körperfremden Verbindung auf einen Organismus wird in aller Regel an dem Begriff der biologischen Aktivität festgemacht. Liegt eine gezielte, therapeutisch relevante und regulierende Wirkung vor, so hat die Verbindung das Potenzial zu einem Arzneistoff, andernfalls betrachtet man ihren toxikologischen Einfluss auf das biologische System. Doch was versteht man unter dem Begriff der biologischen Aktivität? Natürlich ist an dieser Stelle der gesamte Effekt auf einen Organismus zu betrachten, doch wegen der Komplexität der ineinandergreifenden Vorgänge betrachtet man zunächst nur die „Hauptwirkung“ auf den Organismus. Auf die molekulare Ebene übertragen, bedeutet biologische Aktivität die Bindung einer (niedermolekularen) Verbindung an einen makromolekularen Rezeptor, in aller Regel ein Protein. Dadurch werden enzymatische Reaktionen oder Signaltransduktionskaskaden in ihrer Funktion für den Organismus beeinflusst. Wir betrachten diese Bindung als einen Vorgang unter Gleichgewichtsbedingungen, sodass sich die Bindung als Assoziations‐ oder Dissoziationsvorgang beschreiben lässt. Somit wird biologische Aktivität als Affinität der beiden Partner zueinander in Form einer thermodynamischen Gleichgewichtsgröße ausgedrückt. Wie gut sind diese Begriffe heute verstanden und theoretisch vorhersagbar? Kern des rationalen Wirkstoffdesigns ist die Vorhersage der biologischen Aktivität einer Verbindung. Die Vorgänge bei der Ligandenbindung sind äußerst komplex, sowohl Ligand als auch Protein sind flexible Moleküle, und die Energiebilanz muss zwischen getrenntem und gebundenem Zustand in wässriger Umgebung betrachtet werden. Wie ausgereift und aussagekräftig sind unsere experimentellen Verfahren, um hier die notwendigen Einblicke zu gewinnen? Der vorliegende Aufsatz fasst den derzeitigen Kenntnisstand zur Bindungsaffinität eines niedermolekularen Liganden zu einem Protein zusammen. Es werden theoretische wie empirische Ansätze beschrieben und gegenübergestellt, die eine Vorhersage der Bindungsaffinität aus der Raumstruktur eines Protein‐Ligand‐Komplexes zum Ziel haben. Experimentelle Ansätze, vor allem die Mikrokalorimetrie, werden diskutiert. Als Ausblick werden ein eigenes wissensbasiertes Verfahren zur Affinitätsvorhersage und experimentelle Daten zur Faktorisierung von Bindungsbeiträgen zur Ligandenbindung an Proteine vorgestellt.

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Approaches to the Description and Prediction of the Binding Affinity of Small-Molecule Ligands to Macromolecular Receptors

Gohlke

Klebe

2002

Angew. Chem. Int. Ed.

756

674

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The influence of a xenobiotic compound on an organism is usually summarized by the expression biological activity. If a controlled, therapeutically relevant, and regulatory action is observed the compound has potential as a drug, otherwise its toxicity on the biological system is of interest. However, what do we understand by the biological activity? In principle, the overall effect on an organism has to be considered. However, because of the complexity of the interrelated processes involved, as a simplification primarily the "main action" on the organism is taken into consideration. On the molecular level, biological activity corresponds to the binding of a (low-molecular weight) compound to a macromolecular receptor, usually a protein. Enzymatic reactions or signal-transduction cascades are thereby influenced with respect to their function for the organism. We regard this binding as a process under equilibrium conditions; thus, binding can be described as an association or dissociation process. Accordingly, biological activity is expressed as the affinity of both partners for each other, as a thermodynamic equilibrium quantity. How well do we understand these terms and how well are they theoretically predictable today? The holy grail of rational drug design is the prediction of the biological activity of a compound. The processes involving ligand binding are extremely complicated, both ligand and protein are flexible molecules, and the energy inventory between the bound and unbound states must be considered in aqueous solution. How sophisticated and reliable are our experimental approaches to obtaining the necessary insight? The present review summarizes our current understanding of the binding affinity of a small-molecule ligand to a protein. Both theoretical and empirical approaches for predicting binding affinity, starting from the three-dimensional structure of a protein-ligand complex, will be described and compared. Experimental methods, primarily microcalorimetry, will be discussed. As a perspective, our own knowledge-based approach towards affinity prediction and experimental data on factorizing binding contributions to protein-ligand binding will be presented.

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Water at Hydrophobic Surfaces: Weak Hydrogen Bonding and Strong Orientation Effects

Cited by 986 publications

References 21 publications

Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

Polarization and experimental configuration analyses of sum frequency generation vibrational spectra, structure, and orientational motion of the air/water interface

Ansätze zur Beschreibung und Vorhersage der Bindungsaffinität niedermolekularer Liganden an makromolekulare Rezeptoren

Approaches to the Description and Prediction of the Binding Affinity of Small-Molecule Ligands to Macromolecular Receptors

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