The longest acenes.

For a long time, the largest known member of the acene series was hexacene, consisting of six linearly fused benzene rings. The next higher member, heptacene, is so highly reactive that either stabilization using substituents is required or matrix isolation techniques need to be employed for the detection of the parent hydrocarbon. This Record Review summarizes recent research that culminated in the synthesis of substituted and parent nonacene.