Two‐photon absorption enhancement by the inclusion of a tropone ring in distorted nanographene ribbons

Abstract

A new family of distorted ribbon-shape nanographenes was designed, synthesized and their optical and electrochemical properties were measured, pointing out an unprecedented correlation between their structural characteristics and their two photon absorption (TPA) responses and electrochemical band gaps. Three nanographene ribbons have been prepared: a seven-membered ring containing nanographene presenting a tropone moiety at the edge, its full-carbon analogue and the purely hexagonal one. We have found that the TPA cross-sections and the electrochemical band gaps of the seven-membered ring containing compounds are higher and lower, respectively, than those of the fully hexagonal polycyclic aromatic hydrocarbon (PAH). Interestingly, the difference between presenting or not the electron withdrawing group, barely changes these parameters compared with those of the nanoribbon without the heptagon.