Konformasyon

Konformasyon refers to the spatial arrangement of atoms in a molecule that can be changed by rotations around single (sigma) bonds without breaking bonds. Molecules may exist in several conformations, collectively called conformers or conformational isomers. Interconversion between conformers occurs through torsional motion and is influenced by steric interactions and electronic effects. This concept is distinct from configurational isomerism, which requires bond breaking and re-forming, such as cis–trans arrangements or stereocenter inversion.

In open-chain hydrocarbons, rotation about carbon–carbon single bonds creates different conformations; ethane has staggered and eclipsed forms, with the staggered form generally lower in energy. The barrier to rotation is modest, allowing rapid interconversion at room temperature. In butane, anti and gauche conformers dominate, and their relative populations are governed by small energy differences. In cyclic systems, conformational analysis often centers on cyclohexane, which can adopt chair, boat, and twist-boat forms; the chair is the most stable, and interconversion occurs via ring flipping. Substituents influence conformations through steric effects; axial substituents are typically less favorable than equatorial ones due to steric strain, notably 1,3-diaxial interactions.

Conformational changes are also central in biology and pharmacology. Proteins and nucleic acids sample multiple conformations that underlie function, binding, and catalysis. Techniques such as NMR spectroscopy, X-ray crystallography, and computational modeling are used to study konformasyon, linking molecular shape to reactivity and biological activity.