Search results
Results from the WOW.Com Content Network
Scheme 1. Process of NaF formation -- example of an electrostatic interaction. Ionic interactions involve the attraction of ions or molecules with full permanent charges of opposite signs. For example, sodium fluoride involves the attraction of the positive charge on sodium (Na +) with the negative charge on fluoride (F −). [9]
Similar to these other non-covalent bonds, cation–π interactions play an important role in nature, particularly in protein structure, molecular recognition and enzyme catalysis. The effect has also been observed and put to use in synthetic systems. [1] [2] The π system above and below the benzene ring leads to a quadrupole charge distribution.
For example, Na–Cl and Mg–O interactions have a few percent covalency, while Si–O bonds are usually ~50% ionic and ~50% covalent. Pauling estimated that an electronegativity difference of 1.7 (on the Pauling scale ) corresponds to 50% ionic character, so that a difference greater than 1.7 corresponds to a bond which is predominantly ionic.
For a given cation, Pauling defined [2] the electrostatic bond strength to each coordinated anion as =, where z is the cation charge and ν is the cation coordination number. A stable ionic structure is arranged to preserve local electroneutrality , so that the sum of the strengths of the electrostatic bonds to an anion equals the charge on ...
What is more commonly observed (see figure to the right) is either a staggered stacking (parallel displaced) or pi-teeing (perpendicular T-shaped) interaction both of which are electrostatic attractive [2] [3] For example, the most commonly observed interactions between aromatic rings of amino acid residues in proteins is a staggered stacked ...
Figure 1. Example of salt bridge between amino acids glutamic acid and lysine demonstrating electrostatic interaction and hydrogen bonding. In chemistry, a salt bridge is a combination of two non-covalent interactions: hydrogen bonding and ionic bonding (Figure 1).
The electrostatic terms are notoriously difficult to calculate well because they do not fall off rapidly with distance, and long-range electrostatic interactions are often important features of the system under study (especially for proteins). The basic functional form is the Coulomb potential, which only falls off as r −1. A variety of ...
Electrostatic discharge while fueling with gasoline is a present danger at gas stations. [24] Fires have also been started at airports while refueling aircraft with kerosene. New grounding technologies, the use of conducting materials, and the addition of anti-static additives help to prevent or safely dissipate the buildup of static electricity.