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Grafting Behavior for the Resonating Variants of Ethynylaniline on Hydrogenated Silicon (100) Surfaces under Thermal Hydrosilylation
Author(s) -
Tung Joline,
Tew Lih Shin,
Coluccini Carmine,
Lin YueDer,
Khung Yit Lung
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201802003
Subject(s) - acetylene , hydrosilylation , nucleophile , grafting , silicon , x ray photoelectron spectroscopy , chemistry , derivative (finance) , methyl group , photochemistry , group (periodic table) , materials science , polymer chemistry , crystallography , organic chemistry , chemical engineering , catalysis , polymer , financial economics , engineering , economics
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 NH 2 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 NH 2 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 NH 2 group as hypothesized. Thus, for the first time, the interplay between resonance structures and their effects on silicon surface modifications were systematically catalogued.