Self-assembled triphenylamine-hexaazatriphenylene two-photon absorption dyes

This paper reports the self-assembling and two-photon absorption natures of donor–acceptor molecules, tri(phenanthro)hexaazatriphenylene (TPHAT-C) and tri(phenanthrolino)hexaazatriphenylene (TPHAT-N), bearing six electron-donating moieties. In the 1H NMR spectra, a line-broadening effect, arising from self-assembled aggregation was observed. Several hundred nanometer scale aggregates were detected in dynamic light scattering. The one-dimensional aggregation of the TPHAT molecules was indicated by the concentration dependence in UV/vis one-photon absorption and one-photon excited fluorescence spectroscopies. An enhancement of the two-photon absorption cross-section was observed in the self-assembled TPHAT system. The order of the two-photon absorption nature is in agreement with the order of the aggregative nature.