Web Release Date: February 28,
One-Step Preparation of Large-Scale Self-Assembled Monolayers of Cyanuric Acid and Melamine Supramolecular Species on Au(111) Surfaces
State Key Laboratory for Physical Chemistry of Solid Surfaces, Department of Chemistry, Xiamen University, Xiamen 361005, China
Received: August 29, 2007
In Final Form: December 14, 2007
Abstract:
In this paper, a kind of robust self-assembled monolayer (SAM) directed by lateral triple hydrogen bonding interactions was prepared by a one-step reaction of cyanuric acid (CA) and melamine (M) molecules on reconstructed Au(111) surfaces in ambient conditions. The structures of the CA·M SAMs were found to be similar to those of bulk crystals. These physisorbed SAMs, directed by triple hydrogen bonds, were found to be stable at the air/substrate interface and possessed a high thermal stability (up to 400 K). According to the high-resolution STM images, a commensurate structure with respect to the reconstructed Au(111) surfaces was established. Combined with density functional theory (DFT) calculations, the roles of the adsorbate-adsorbate and the adsorbate-substrate interactions, as well as the origin of the high stability of the CA·M SAMs, were discussed. In addition to the preparation of the CA·M SAMs, SAMs of melamine and cyanuric acid molecules alone were also studied on the Au(111) surfaces. Chiral structures were found in both of these SAMs. Structural models of melamine SAMs and cyanuric acid SAMs were established.
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