A difluorenyl-carbo-cyclohexadiene: prospective chromophore for two-photon absorption

Abstract

For the purpose of outlining structure-property relationships for two-photon absorption (2PA), a "s-locked" carbo-cyclohexadiene with two fluorenyl substituents has been envisaged for comparison with previously studied aromatic carbo-benzene and non-aromatic carbo-quinoid congeners. A representative where the C10-π-conjugated fluorenyl moieties are also connected by a C8-π-insulating 3,6‐dimethoxy‐3,6‐bis(trifluoromethyl)octa‐1,4,7‐triyn-1,8-diyl edge has thus been synthesized in four steps from known C8F triyne and C10 triynyldial, through a [8F+10] cyclization process. In spite of a relatively strong absorbance (e = 84 800 L.mol-1.cm-1 at 634 nm), the non-vanishing green fluorescence (at 533 nm) of the chromophore should allow measurements of the 2PA cross section by both the TPEF and Z-scan methods.