Two-photon absorption properties of alkynyl-conjugated pyrene derivatives.

A series of pyrene derivatives having 4-(N,N-dimethylamino)phenylethynyl groups as the substituent (1-5) have been synthesized and their two-photon absorption properties were investigated. Comparison of two-photon cross section (delta(max)) with related compounds reveals that pyrene is as efficient a pi-center as anthracene in two-photon materials. Moreover, the two-photon cross section (delta(max)) increased with the number of substituents reaching at the maximum value of 1150 GM for the tetra-substituted derivative (5). Furthermore, the two-photon action cross section (Phi delta(max)) of 5 is comparable to that the most efficient two-photon materials. This result provides a useful guideline to the design of efficient two-photon materials bearing pyrene as a pi-center.