title: Tridentate benzylthiols on Au(111): control of self-assembly geometry.
abstract: A set of hexasubstituted benzene derivatives with three thiol groups in the 1, 3, 5 positions and varied aliphatic substituents in the 2, 4, 6 positions (Me3-BTMT, Et3-BTMT, ODe3-BTMT) has been synthesized and self-assembled on Au(111). The resulting self-assembled monolayers (SAMs) are characterized by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and electrochemistry. The molecular orientation and long-range order are affected by the “gear effect” of the hexasubstituted benzene ring and van der Waals interactions between the physisorbed alkyl chains drive. Me3-BTMT adopts a standing up orientation which results in the highest molecular surface density but also the lowest degree of chemisorption (1 to 2 Au–S bonds per molecule). In contrast, Et3-BTMT favors a lying down orientation with a greater number of surface-bonded thiol groups (2 to 3) per molecule, associated with the peculiar geometry of this molecule. Finally, ODe3-BTMT adsorbs mainly in a lying down orientation, forming the SAM with the highest degree of chemisorption (all thiol groups are gold-bonded) and the lowest molecular areal density.
authors.affiliation: Department of Chemistry and Centre for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke St. West, Montreal (QC) H3A 0B8, Canada. Bruce.Lennox@mcgill.ca Dmitrii.Perepichka@mcgill.ca.
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Mezour
authors.forename: Iryna I
authors.initials: II
authors.lastname: Perepichka
authors.forename: Oleksandr
authors.initials: O
authors.lastname: Ivasenko
authors.forename: R Bruce
authors.initials: RB
authors.lastname: Lennox
authors.forename: Dmitrii F
authors.initials: DF
authors.lastname: Perepichka