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A bridge worth crossing: Various phosphonium- and borate-bridged bis(arylethenyl)benzenes were synthesized. The large two-photon absorption (TPA) cross sections in these zwitterionic ladder π-electron systems revealed that the introduction of zwitterionic bridges in the coplanar π-conjugated framework is a powerful strategy for designing excellent TPA materials.
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Fukazawa et al. (2010) studied this question.
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