Self-Organized Supported Clusters of L-Methionine

Fundamental understanding of self-organization and integration of biomaterials on semiconductors is essential to the development of biological electronic devices. While formation of supramolecular structures by hydrogen bonding and/or electrostatic forces appears common on metal surfaces, the availability of dangling bonds on semiconductor surfaces introduces new bonding mechanisms that could disrupt the self-organization of basic biomolecules. Here, we demonstrate self-organization of L-methionine on Si(111)7X7 at room temperature into a Y-shaped trimer, as the first "perfect-match" supported cluster reported to date. The Y trimer is found to be securely attached within the 7X7 half unit cell and is driven by intralayer hydrogen bonding among the unattached carboxylic acid groups in a ring configuration. Its unique cluster structure is verified by ultra-large-scale density functional theory calculations with van der Waals corrections. The Y trimer (key) offers a remarkably stable "lock-and-key" fit to the 7X7 unit cell (lock) for biofunctionalization and molecular templating.