Photoresponsive SAMs on gold fabricated from azobenzobene-functionalised asparagusic acid derivates

  • chair: Siemeling, U. / Bruhn, C. / Bretthauer, F. /  Borg, M. / Traeger, F. / Vogel, F. /  Azzam, W. /  Badin, M. / Strunskus, T. / Wöll, C. (2009)

  • place:

    Dalton Transactions 40 (2009), 8593-8604

  • Date: 2009
  • Siemeling, U. / Bruhn, C. / Bretthauer, F. /  Borg, M. / Traeger, F. / Vogel, F. /  Azzam, W. /  Badin, M. / Strunskus, T. / Wöll, C. (2009): „Photoresponsive SAMs on gold fabricated from azobenzobene-functionalised asparagusic acid derivates “. In: Dalton Transactions 40 (2009), 8593-8604


We have prepared a range of azobenzene derivatives equipped with an asparagusic acid-based 1,2-dithiolane headgroup suitable for chemisorption on solid gold substrates. The formation of self-assembled monolayers (SAMs) of the amide cyclo-S2C3H5-4-C(O)NH-p-C6H4-N=N-Ph (1) and the ester cyclo-S2C3H5-4-C(O)O-p-C6H4-N=N-Ph (2) on gold was monitored in situ and in real time by optical second harmonic generation (SHG).

The structure and composition of these SAMs was investigated by a range of ex situ methods, viz. ellipsometry, X-ray photoelectron spectroscopy (XPS), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and Fourier transform infrared reflection absorption spectroscopy (FTIRRAS). Reversible, but moderate, photoswitchability was observed for these one-component SAMs by ellipsometry and dynamic contact angle measurements. Use of a second 1,2-dithiolane component for lateral dilution of the photoactive terminal groups resulted in a much more pronounced photoresponse.


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