Structure of N-(2-hydroxyethyl)-3-mercaptopropanamide (NMPA) monolayer on Au surface

The first-principles technique has been employed to determine the structure of N-(2-hydroxyethyl)-3-mercaptopropanamide (NMPA) molecular chains, monolayers, and the adsorption system. The CASTEP calculation confirms that the NMPA monolayer forms a self-assembly system consisting of numerous parallel molecules interconnected through H-O bonds. This finding is supported by the electron density analysis. The monolayers of NMPA are composed of molecular chains arranged in either parallel or alternating configurations. Upon adsorption of the NMPA monolayer onto the Au surface, the structural parameters within the adsorption system remain consistent with those observed in the monolayer, indicating that the structure of the NMPA self-assembled monolayers is primarily governed by intermolecular interactions. The primary parameter imparted by the Au surface is the distance between adjacent molecules within the molecular chain.