Synthesis and structure-linear and structure-nonlinear optical properties of multi-dipolar zigzag oligoaryleneethynylenes

Kwan Lo Pik, Fai Li King, Ricky M S WONG*, Kok Wai CHEAH

*Corresponding author for this work

Research output: Contribution to journalJournal articlepeer-review

5 Citations (Scopus)


(Chemical Equation Presented) A novel series of monodisperse, multi-dipolar zigzag oligoaryleneethynylenes DA(n) and D-Ar-A(n), bearing electron-donating dibenzothiophene and electron-accepting dibenzothiophene dioxide as arenes, with up to six charge-transfer (dipolar) units have been designed and synthesized by palladium-catalyzed Sonogashira coupling reactions. The linear and nonlinear optical properties of these multi-dipolar oligoaryleneethynylenes can easily be modified or enhanced by incorporating/extending with various central aryleneethynyl moieties such as phenylethynyl, oligo(9,9-dibutylfluorenyl) ethynyl, and oligothienylethynyl within the donor - acceptor units. Interestingly, the absorption and emission of these zigzag oligoaryleneethynylenes are not dependent on the number of covalently linked dipolar chromophores; however, the fluorescence quantum efficiencies consistently decrease with increased number of covalently linked dipolar units. These zigzag oligoaryleneethynylenes exhibit a linear increase in the two-photon absorption (TPA) cross-sections with increased number of covalently linked dipolar units without red-shifting the absorption and emission spectra. In addition, very large TPA cross-sections in the femtosecond regime (σ800 = 1306 GM in DMF or σ750 = 1522 GM in CH2Cl2) were obtained for D-TF-A(4) despite the moderate strength of the donor - acceptor pair. Our results suggest that the TPA properties of these zigzag oligoaryleneethynylenes including TPA wavelength and TPA cross-section can easily be tuned by means of modifying the central aryleneethynylene units and increasing the number of dipolar units, respectively. This approach provides an alternative means to tune or enhance the TPA cross-section at a specific wavelength.

Original languageEnglish
Pages (from-to)6672-6679
Number of pages8
JournalJournal of Organic Chemistry
Issue number18
Publication statusPublished - 31 Aug 2007

Scopus Subject Areas

  • Organic Chemistry


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