Metal-ion sensing fluorophores with large two-photon absorption cross sections: aza-crown ether substituted donor-acceptor-donor distyrylbenzenes.
Pond SJ, Tsutsumi O, Rumi M, Kwon O, Zojer E, Br?das JL, Marder SR, Perry JW. Metal-ion sensing fluorophores with large two-photon absorption cross sections: aza-crown ether substituted donor-acceptor-donor distyrylbenzenes. J Am Chem Soc. 2004 Aug 04; 126(30):9291-306.