Waals Interactions and Hydrogen Bonding

A6-12 function (also known as a Lennard-Jones function) frequently simulates van der Waals interactions in force fields (equation 11). 

The AMBER force field replaces the van der Waals by a 10-12 potential for pairs of atoms that can participate in hydrogen bonding (equation 12). The hydrogen bond potential does not contribute significantly to the hydrogen bonding attraction between two atoms rather, it is implemented to fine-tune the distances between these atoms. 

Eomple In this example, the van der Waals (6-12) and hydrogen bond (10-12) potentials are quickly damped. 

The attraction for two neutral atoms separated by more than four Angstroms is approximately zero. The depth of the potential wells is minimal. For the AMBER force field, hydrogen bonds have well depths of about 0.5 kcal/mol the magnitude of individual van der Waals well depths is usually less. 

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The native, biologically active form of a protein molecule is held together by a delicate balance of noncovalent forces hydrophobic, ionic, van der Waals interactions, and hydrogen bonds. In addition,... 

The remaining portion of the - 1 residue (C3-C6 and 03-06) is not mimicked by the peptide. This face of the ring contacts Trp 403 through van der Waals interactions and hydrogen bonds from 07 to Trp 403 NEl and Gin 407 NE2, and the peptide does not make corresponding contacts. The - 2 sugar... 

Food flavor is a very important parameter influencing perceived quality. The volatile compounds contributing to the aroma of foods possess different chemical characteristics, such as boiling points and solubilities and the sensory properties of food cannot be understood only from the knowledge of aroma composition. This can be explained by interactions between flavor compounds and major constituents in food such as fat, proteins and carbohydrates (1). A number of different interactions has been proposed to explain the association of flavor compound with other food components. This includes reversible Van der Waals interactions and hydrogen bonds, hydrophobic interactions. The understanding of interactions of flavor with food is becoming important for the formulation of new foods or to... 

When a sample of polymer is fractured, the creation of the new surfaces must necessarily involve the breakage of primary (covalent) bonds or secondary bonds (van de Waals interactions and hydrogen bonds), or both... 

A secondary structure refers to the spatial relationship of near neighbors, which is a result of the geometry of each individual sugar and their intermolecular type interactions such as van der Waals interactions and hydrogen bonding. 

The spontaneous formation of structures by self-assembly relies on a delicate balance of relatively weak intermolecular forces such as the hydrophobic force, electrostatic and van der Waals interactions, and hydrogen bonding. Building blocks for self-assembly can range from small atoms to much larger macroscale objects. A wide variety of two- and three-dimensional... 

Thermodynamic parameters and nature of the binding force. The interaction forces between a drug and a biomolecule may include hydrophobic forces, electrostatic interactions, van der Waals interactions, and hydrogen bonds. From the thermodynamic parameter calculation, the acting force can be identified.6 For the interaction of HSA and EHC, at 25 °C and 37 °C, A H=4.68 kJ/mol and A S=107 J/mol/K. While A G = -27.3 kJ/mol (25 °C), -28.6 kJ/mol (37 °C). It can be seen the positive value of AS indicate that the hydrophobic forces played a major role in the reaction. At the same time, hydroxyl and carbonyl groups in the EHC presumably interacted with polar groups of HSA, so the main sort of binding force between them probably includes both hydrophobic and dipole forces. 

Using a similar approach to forming synthetic capsules, other structures have been designed that utilize attractive interactions between the host and the guest, other than van der Waals interactions and hydrogen bonding. One example is the formation of a capsule (56) from two equivalents of bowl-shaped Lewis acid precursor, aluminum tris(2.6-di-phenylphenoxide) (ATPH) 55, with a guest such as 1,4-cyclohexanedione (Scheme 4-14)... 

The fundamental factor that controls the packing mode in the crystals is the intermolecular interactions. The intermolecular interactions, including electrostatic interactions, van der Waals interactions, and hydrogen bonding interactions, differ significantly between the racemic compound and the... 

It is easily understandable that chemical bonds formed across the adhesive substrate interface can greatly participate to the level of adhesion between both materials. These bonds are generally considered as primary bonds in comparison with physical interactions, such as van der Waals, which are called secondary force interactions. The terms primary and secondary stem from the relative strength or bond energy of each type of interaction. The typical strength of a covalent bond, for example, is on the order of 100 to 1000 kJ/mol, whereas those of van der Waals interactions and hydrogen bonds do not exceed 50 kJ/mol. It is clear that the formation of chemical bonds depends on the reactivity of both adhesive... 

On the other hand, it is important to say that chitin-pwlyurethane interaction has an important physical component, since attraction forces as Van der Waals interactions and hydrogen bonds are present at the interface chitin-polyurethane. This aspect could have caused that chitin-polyurethane chemical interaction was not strong enough to be more clearly observed by means of the FTIR-ATR analysis. In addition, chitin was added to the biocomposite in solid form, which limits the achievability of amine and hydroxyl groups of chitin surface due to a steric impediment. Other important aspect to point out is that polyurethane film thickness over the interface chitin-polyurethane could be irregular, which could difficult to reach the chitin-polyurethane interface by infrared light. 

Evidence has been obtained in support of an earlier suggestion that the attachment of p-D-galactosidase and lysozyme to collagen membranes by an impregnation process involves multiple ionic and van der Waals interactions and hydrogen bonds. ... 

In general, ILs are more viscous than water, which in some cases can be disadvantageous for applications, for example, in organic reactions. Molar mass, van der Waals interactions, and hydrogen bonds, among other factors, have influence on viscosity (Chiappe and Pieraccini, 2005). 

Three major classes of surfactant molecules can be harnessed for soft templating cationic, anionic, and nonionic surfactants. In soft templating, ionic surfactants typically interact with precursors via electrostatic interactions, including interactions with ions. Self-assembly processes with nonionic surfactants are primarily mediated by van der Waals interactions and hydrogen bonding. 

After modeling, the structures are encoded with molecular structure descriptors. The descriptors are designed to represent the aspects of the molecules that influence their ability to engage in intermolecular interactions such as dipole-dipole interaction.s, van der Waals interactions, and hydrogen bonding. The descriptors fall into four classes topological (see... 

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