Conjugation is an arrangement of alternating multiple bonds (or an empty orbital) and single bonds in which adjacent p orbitals overlap side by side, allowing the π electrons to spread out over several atoms. It matters because this delocalisation lowers the energy of the system, giving extra stability, and it also affects colour and reactivity. For example, conjugation stabilises the carboxylate ion and is responsible for the colour of many dyes.

共轭是多重键(或一个空轨道)与单键交替排列的结构,其中相邻的 p 轨道侧向重叠,使 π 电子得以分布于多个原子之上。它之所以重要,是因为这种离域降低了体系的能量,带来额外的稳定性,同时也影响颜色和反应活性。例如,共轭使羧酸根离子稳定,并且是许多染料显色的原因。