Two-Dimensional Self-Assembly Monitored by Hydrogen Bonds for Triphenylene-Based Molecules: New Role for Azobenzenes

Abstract

A hybrid disk-like/rod-like molecule comprising central triphenylene core symmetrically substituted with six azobenzene moieties (C-12) has been adsorbed at the 1,2,4trichlorobenzene/Au(111) interface, revealing the potential of azobenzene moieties for the control of 2D chiral networks. The C-12, which due to its complex molecular structure possesses a relatively large number of degrees of freedom, surprisingly forms monolayers of only one kind of structure, namely a hexagonal network of large period, 3.5 nm. By combining Scanning Tunneling Microscopy (STM) and DFT calculations, we evidence that this specific 2D-ordering is due to cooperative weak hydrogen bonds between neighboring azobenzenes and azobenzene-Au(111) interactions. The crystallographic network is hexagonal, but azobenzene-azobenzene pairing, associated with hydrogen bonding renders the network chiral with a chirality spanning all ranges, from the molecular C-12 configuration, the configuration of the azobenzene dimers and the rosette-like azobenzene network, to the C-12 network orientation on Au(111) rotated by ±8° from the main crystallographic direction Au<110>, depending on the handedness of the molecular network. This chiral 2D system thus paves the way for the formation of macroscopic 2D molecular crystals of unique handedness, if additional enantiomeric chiral dopants can be used.

Nanopatterns of arylene–alkynylene squares on graphite: self-sorting and intercalation

“…On the other hand, reports on intercalated TCB molecules are rather rare. Two exceptions are the observations of TCB in monolayers of arylene–alkynylene pentagons as well as triphenylene/azobenzene-based molecules on Au(111)) [34–35].…”

Where do the counterions go? Tip-induced dissociation of self-assembled triazatriangulenium-based molecules on Au(111)

“…These optimized basis sets have been well-tested in previous works on molecular self-assembly on metallic surfaces. [27][28] we have determined the adsorption energy of the TATA + ion on the gold surface, with and without the counterion BF4 -. The adsorption energy is defined in a standard manner as the difference between the total energy of the system and the energy of the isolated molecule and the isolated gold surface calculated independently.…”

Electrostatically Driven Guest Binding in Self-Assembled Molecular Network of Hexagonal Pyridine Macrocycle at the Liquid/Solid Interface: Symmetry Breaking Induced by Coadsorbed Solvent Molecules

“…STM visualization of TCB molecules co-adsorbed in macrocyclic interiors 41,[72][73][74] as well as in the space between adsorbed molecules was reported previously. 41,75 To support this hypothesis, we performed molecular mechanics (MM) simulations using COMPASS force field for a single molecule of unsubstituted PyBM adsorbed on a graphene bilayer as a graphite model and compared it with a complex incorporating two molecules of TCB in the nanopore ( (Table S1), co-adsorption of TCB molecules stabilizes the system significantly by 39.3 kcal/mol. The bond angles of the butadiyne linkage are slightly more distorted (up to ca.…”