Dynamics of grain boundaries in two-dimensional hydrogen-bonded molecular networks.
The temporal evolution of domain boundaries of hydrogen-bonded molecular monolayers at the liquid-solid interface is evaluated by recording series of subsequent scanning tunneling microscopy (STM) images. Comparison of dissimilar benzene carboxylic acids reveals a clear distinction between one- and two-dimensional H-bonded network structures. Trimesic acid forms a two-dimensionally H-bonded networked structure, whereas terephthalic acid organizes in a dense packing of H-bonded linear chains on a graphite surface. In addition, TMA forms a sixfold lattice on a threefold graphite substrate, whereas TPA exhibits only a twofold lattice, causing a high grain-boundary line energy for the latter. In the case of TMA the nanostructure was mostly stable during the observation time. For TPA, Ostwald ripening-that is, the growth of larger islands at the expense of smaller islands-was observed. To explain the various experimentally observed timescales of the dynamics occurring at grain boundaries, molecular mechanics simulations were applied to calculate the binding energy of edge molecules, that is, the line energy, of finite islands of both trimesic and terephthalic acid on a graphite substrate.
Lackinger
Markus
M
Ludwig-Maximilians-Universität München, Departement für Geo- und Umweltwissenschaften & Center for NanoScience (CeNS), Theresienstr. 41, 80333 München, Germany. markus@lackinger.org
Griessl
Stefan
S
Kampschulte
Lorenz
L
Jamitzky
Ferdinand
F
Heckl
Wolfgang M
WM
D000327:Adsorption; D001554:Benzene / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry; D006108:Graphite; D006358:Hot Temperature; D006860:Hydrogen Bonding; D016252:Microscopy, Scanning Tunneling / Q000379:methods*; D008958:Models, Molecular; D036103:Nanotechnology / Q000379:methods*; D010795:Phthalic Acids / Q000737:chemistry; D012997:Solvents; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014233:Tricarboxylic Acids / Q000737:chemistry
D002264:Carboxylic Acids; D010795:Phthalic Acids; D012997:Solvents; D014233:Tricarboxylic Acids; C011363:terephthalic acid; D006108:Graphite; D001554:Benzene; C069849:trimesic acid