Synthesis and two-photon properties of small dendritic chromophores with symmetrical and unsymmetrical substituted skeletons

A set of novel multi-branched chromophores consisting of two groups of fluorene/oxadiazole-based analogues with generic skeletons of donor-π-acceptor (unsymmetrical) and donor-π-acceptor-π-donor (symmetrical) type has been synthesized and shown to display strong and broadly dispersed two-photon absorptivities in the near infrared (NIR) region on irradiation with femtosecond laser pulses. It is also demonstrated that structural parameters such as the number of donor units attached and the substitution pattern are closely connected to the molecular two-photon activities of these model compounds.