Strong Two‐Photon Absorption of Singlet Diradical Hydrocarbons

Abstract

Ones and twos: The two-photon absorption cross sections (σ(2)) of singlet diradical hydrocarbons with phenalenyl peripheral groups (see scheme) are larger than those of closed-shell aromatic hydrocarbons by an order of magnitude or more and are comparable to those of π-conjugated compounds with strong electron donor or acceptor substituents. A significant increase in cross section was also observed in the resonance-enhanced region.