  Although common in nature, the self-assembly of small molecules at
sold-liquid interfaces is difficult to control in artificial systems. The high
mobility of dissolved small molecules limits their residence at the interface,
typically restricting the self-assembly to systems under confinement or with
mobile tethers between the molecules and the surface. Small hydrogen-bonding
molecules can overcome these issues by exploiting group-effect stabilization to
achieve non-tethered self-assembly at hydrophobic interfaces. Significantly,
the weak molecular interactions with the solid makes it possible to influence
the interfacial hydrogen bond network, potentially creating a wide variety of
supramolecular structures. Here we investigate the nanoscale details of water
and alcohols mixtures self-assembling at the interface with graphite through
group effect. We explore the interplay between inter-molecular and surface
interactions by adding small amounts of foreign molecules able to interfere
with the hydrogen bond network and systematically varying the length of the
alcohol hydrocarbon chain. The resulting supramolecular structures forming at
room temperature are then examined using atomic force microscopy with insights
from computer simulations. We show that the group-based self-assembly approach
investigated here is general and can be reproduced on other substrates such as
molybdenum disulphide and graphene oxide, potentially making it relevant for a
wide variety of systems.
