Tridentate benzylthiols on Au(111): control of self-assembly geometryElectronic supplementary information (ESI) available: Synthetic procedure and 1H, 13C NMR and MS characterization of Me3-BTMT, Et3-BTMT, ODe3-BTMT and ODe3-B. STM images of 1-octanethiol, approximate molecular dimensions of Me3-BTMT and Et3-BTMT, DFT calculated rotational itinerary for Et3-BTMT and pair correlation analysis of the nearest three-point contacts for Me3-BTMT, Et3-BTMT and ODe3-BTMT. See DOI: 10.1039/c4nr07207c

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 ( Me 3 -BTMT , Et 3 -BTMT , ODe 3 -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. Me 3 -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, Et 3 -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, ODe 3 -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. 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 ( Me 3 -BTMT , Et 3 -BTMT , ODe 3 -BTMT ) has been synthesized and self-assembled on Au(111).