The enhanced two-photon absorption behavior of twistfuranacenes to phenylacetylene-functionalized twistacenes
Three novel furanacenes (5/D5c) have been synthesized and characterized. Single-crystal analyses suggested that the as-prepared molecules 5a/5b formed twisted configurations. The absorption and emission spectra of these compounds (5/D5c) and their precursors, alkynyl-modified acenes (3), were measured to uncover the substituent effect on their optoelectronic properties. Twistfuranacenes 5a/5b and substituted twistacenes 3 emit strong blue light, and the triphenylamine-decorated π-system D5c exhibited obviously red-shifted fluorescence. Nonlinear spectroscopic investigation illustrated that the cyclized furanacenes 5/D5c presented larger two-photon absorption cross section than twistacenes 3, being attributed to the introduction of more delocalized electrons from electron-rich furan units. Apparently, these observations might be beneficial for the design of novel twistacenes/heteroacenes and the development of organic photonic materials.