Synthesis and Optical Properties, Including Two-Photon Absorption Cross-Sections, of Differentially Functionalized Starburst-Type π-Conjugated Molecules

Differentially functionalized hexakis(p-substituted-phenylethynyl)benzene and hexakis[4-(p-substituted-styryl)-phenylethynyl]benzene derivatives with various (D 6h , D 3h , D 2h , and C 2υ ) symmetries were synthesized by Sonogashira cross-coupling reactions. The optical properties of this starburst-type π-conjugated system were investigated. Among them, hexakis[4-(p-dioctylaminostyryl)phenylethynyl]benzene (5) showed the largest two-photon absorption cross-section of δ = 818 GM at 800 nm, which was determined by open aperture Z-scan with 120 fs laser pulses in toluene solution.