AVS 51st International Symposium
    Surface Science Monday Sessions
       Session SS-MoP

Paper SS-MoP38
Chemical Binding of N-Containing Aromatic Molecules on Si Surfaces: Mechanistic Understanding of the Selectivity of Reaction Channels

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: F. Tao, Princeton University
Authors: F. Tao, Princeton University
G.Q. Xu, National University of Singapore, Singapore
Correspondent: Click to Email
Chemical binding of organic molecules on Si surfaces is an important approach for fabricating molecular architectures to develop Si-based molecular devices and biosensors. Our studies on attachment chemistry of pyrrole, N-methylpyrrole and pyridine demonstrate the diversity of reaction channels of aromatics on Si surfaces. Pyrrole dissociatively chemisorbs onto Si surfaces through breaking the N-H bond, forming a pyrrolyl ring. Due to the absence of the N-H bond, N-methylpyrrole covalently binds to Si surfaces via pericyclic reactions. The difference of chemisorption mechanism between pyrrole and N-methylpyrrole demonstrates a strategy of switching the reaction channel by introducing substituted group. Besides the pericyclic reaction, pyridine can chemically bond to Si surfaces with the formation of SiN dative bond. Compared to pyrrole and N-methylpyrrole, the ability of pyridine to form a dative bond results from higher electron density around the N atom. This is due to localization of the lone-pair electrons on the N-atom for pyridine, contrasted with participation in the aromatic conjugation for pyrrole and N-methylpyrrole.