부산대학교 도서관

A series of D–π–A–π–D type chromophores were synthesized by the dehydration reaction of 4-R₂N-benzaldehye (R = Ph, Bun, Et, Me) and diaminomaleonitrile (corresponding to the chromophores 1, 2, 3 and 4, respectively), in which a polar imino double bond (–C&z.dbd;N–) replaced the double bond (–CH&z.dbd;CH–) in the π-conjugated centers. Femtosecond laser induced fluorescence intensity was used to evaluate two-photon absorption (TPA) cross sections, δ, using a USB-2000 CCD. Results show a change of terminal groups from Ph₂N– to Me₂N– influenced the δ value significantly through a change of the quantum yield, ϕ. However, the two-photon absorption peak position was only slightly affected. The chromophores 2 and 3 were found to afford polymers in the presence of the functional triacrylate monomer at low laser power at 755 and 820 nm. This demonstrated that the enhanced δ value was not a main factor in the improvement of chromophore two-photon photosensitivity. Such information can be useful in the design of more efficient two-photon chromophores for imaging and power-limiting applications.