Degenerate Two‐Photon Absorption and Effective Optical‐Power‐Limiting Properties of Multipolar Chromophores Derived from 2,3,8‐Trisubstituted Indenoquinoxaline

Two analogous multipolar chromophores ( 1 and 2 ) that contained 2,3,8‐trisubstituted indenoquinoxaline moieties have been synthesized and characterized for their two‐photon absorption properties, both in the femtosecond and nanosecond time regimes. We demonstrated that their multi‐branched framework structures, which incorporated appropriately functionalized indenoquinoxaline units, afforded large molecular nonlinear absorptivities within the studied spectroscopic range. Effective optical‐power‐limiting and stabilization behaviors in the nanosecond regime of dye molecule ( 2 ) were also investigated and the results indicated that such a structural motif could be a useful approach to the molecular design of highly active two‐photon systems for quick‐response and related broadband optical‐suppressing applications, in particular for confronting laser pulses of a long duration.