Conjugated system

A molecular arrangement in which adjacent p orbitals overlap across alternating single and multiple bonds, allowing electrons to delocalize across several atoms.

Pi bond: A covalent bond formed by sideways overlap of parallel orbitals, with electron density above and below the internuclear axis. Its p orbitals overlap along a conjugated chain, spreading π electrons across multiple atoms.
Hybridization: A model for combining atomic orbitals into directed hybrid orbitals used in covalent bonding. The hybridization of atoms determines whether each can retain a p orbital for conjugation.
UV–visible spectroscopy: A spectroscopic method that measures absorption of ultraviolet and visible light by a sample. Conjugated molecules absorb light when electrons are promoted between delocalized electronic states.
Isolated double bond: A double bond separated from other π bonds by two or more single bonds. Its π electrons remain localized rather than joining a continuous conjugated pathway.
Molecular orbital: A wavefunction describing an electron state distributed across one or more atoms in a molecule. Conjugation is described by molecular orbitals extending over several adjacent atoms.
Alkene: A hydrocarbon containing at least one carbon–carbon double bond. An alkene supplies a π bond that can join a conjugated sequence.
Chromophore: The part of a molecule responsible for its characteristic absorption of light. Conjugated π systems commonly form the light-absorbing core of chromophores.
Cumulated diene: A molecule with two adjacent carbon–carbon double bonds sharing one carbon atom. Its perpendicular π systems differ from the alternating-bond arrangement of ordinary conjugation.
Resonance: A representation of molecular electronic structure using multiple contributing Lewis structures. Resonance structures depict alternative placements of electrons in a conjugated system.
Alkyne: A hydrocarbon containing at least one carbon–carbon triple bond. An alkyne can participate in conjugation when an adjacent p-orbital pathway is available.

Linked from 45 pages