Cruz, M. C., Marquez, I. R., Mariz, I. F. A., Blanco, V., Sánchez Sánchez, C., Sobrado, J. M., Martín Gago, J. A., Cuerva, J. M., Macoas, E., Campana, A. G. 2018. Enantiopure distorted ribbon-shaped nanographene combining two-photon absorption-based upconversion and circularly polarized luminescence. Chemical Science 9, 16, 3917-3924 DOI: 10.1039/c8sc00427g
Herein we describe a distorted ribbon-shaped nanographene exhibiting unprecedented combination of optical properties in graphene-related materials, namely upconversion based on two-photon absorption (TPA-UC) together with circularly polarized luminescence (CPL). The compound is a graphene molecule of ca. 2 nm length and 1 nm width with edge defects that promote the distortion of the otherwise planar lattice. The edge defects are an aromatic saddle-shaped ketone unit and a [5]carbohelicene moiety. This system is shown to combine two-photon absorption and circularly polarized luminescence and a remarkably long emission lifetime of 21.5 ns. The [5]helicene is responsible for the chiroptical activity while the push-pull geometry and the extended network of sp(2) carbons are factors favoring the nonlinear absorption. Electronic structure theoretical calculations support the interpretation of the results.
