Eikovalenttien

Eikovalenttien, or non-covalent interactions, are forces that mediate attraction between atoms or molecules without sharing electron pairs. They contrast with covalent bonds, which involve orbital overlap and enduring electron sharing. Non-covalent interactions are usually weaker than covalent bonds, but they can accumulate to yield strong, yet reversible, associations essential for molecular recognition and assembly.

Major types include hydrogen bonds, ionic interactions, dipole-dipole forces, and London dispersion forces. Hydrogen bonds form between a hydrogen donor (such as OH, NH) and an electronegative acceptor (O, N, F) and typically range from roughly 5 to 30 kilojoules per mole, depending on geometry and environment. Ionic interactions, including salt bridges, arise from electrostatic attraction between charged groups and are highly sensitive to solvent polarity. Dipole-dipole and dipole-induced dipole interactions occur between polar molecules or polarizable species. London dispersion forces originate from instantaneous fluctuations in electron density and are universal but vary with molecular size and polarizability. Hydrophobic effects, driven by the ordering of water around nonpolar surfaces, also contribute to assembly in biological contexts. Specialized non-covalent interactions such as cation–pi and pi–pi stacking further stabilize aromatic and charged assemblies.

Biomolecules rely on non-covalent interactions for folding, stability, and binding. DNA base pairing is stabilized primarily by hydrogen bonds; protein structure is guided by a network of hydrogen bonds and hydrophobic interactions; ligand binding involves a balance of these forces. Techniques such as calorimetry, spectroscopy, and crystallography, along with molecular modeling, study these interactions.