Affiliations 

  • 1 College of Arts and Sciences, University of North Carolina at Chapel Hill (UNC), Chapel Hill, NC, 27514, USA
  • 2 Advanced Medical and Dental Institute (AMDI), Universiti Sains Malaysia, 13200, Kepala Batas Pulau Pinang, Malaysia
  • 3 Institute of New Drug Development, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
  • 4 Department of Automatic Control Engineering, Feng Chia University, No. 100, Wenhwa Rd., Seatwen, Taichung, Taiwan
  • 5 Department of Biological Science and Technology, China Medical University, No.91 Hsueh-Shih Road, Taichung, Taiwan
Chemistry, 2018 Jun 22.
PMID: 29932257 DOI: 10.1002/chem.201802003

Abstract

This work reports the outcome of thermal grafting of 2-ethynylaniline, 3-ethynylaniline, and 4-ethynylaniline on a hydrogenated Si(100) surface. Using high-resolution XPS and AFM, it was found that the grafting of these compounds could be attributed to resonating structures that arise from the position of an electron-donating NH2 group and an electron-withdrawing acetylene group. For the ortho- and para-positioned acetylene group, surface reactions were observed to proceed predominantly via the acetylene to form a Si-C bond, whereas the meta-positioned acetylene group was found to have undergone nucleophilic grafting through the NH2 group onto the silicon surface to form a Si-N bond. Furthermore, a tert-butoxycarbonyl-protected derivative for a meta-positioned ethynylaniline was synthesized to exclusively force the reaction to react with the acetylene group and subsequent analysis confirmed that unprotected 3-ethynylaniline had indeed reacted through the nucleophilic NH2 group as hypothesized. Thus, for the first time, the interplay between resonance structures and their effects on silicon surface modifications were systematically catalogued.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.