The adsorption of 1,3,5-Benzenetricarboxylic (Trimesic) Acid (TMA) to a single crystal graphite surface has been studied under Ultra High Vacuum conditions. This work focuses on inducing a particular self-assembly structure by OMBE (Organic Molecular Beam Epitaxy), characterized by periodic non-dense-packing of the molecules. Two coexisting phases could be imaged with sub-molecular resolution by STM. Induced by directed hydrogen bonding, the organic molecules built in both cases a two-dimensional grid architecture with molecular caves. This two-dimensional host structure can accept single trimesic acid guest molecules in different positions.

The adsorption of 1,3,5-Benzenetricarboxylic (Trimesic) Acid (TMA) to a single crystal graphite surface has been studied under Ultra High Vacuum conditions. This work focuses on inducing a particular self-assembly structure by OMBE (Organic Molecular Beam Epitaxy), characterized by periodic non-dense-packing of the molecules. Two coexisting phases could be imaged with sub-molecular resolution by STM. Induced by directed hydrogen bonding, the organic molecules built in both cases a two-dimensional grid architecture with molecular caves. This two-dimensional host structure can accept single trimesic acid guest molecules in different positions.

Two-dimensional molecular-packing structure and monolayer preparation of adenine adsorbates on the graphite ͑0001͒ surface have been studied using scanning tunneling microscopy, low-energy electron diffraction, and thermal-desorption spectroscopy. By combining real-space images and diffraction data a close-packed hydrogen-bonded network of adenine dimers is proposed, containing two dimers in a unit cell with the symmetry group p2gg. The energy-minimized molecular arrangement could be determined by force field calculations. Adenine adsorbate layers were prepared by sublimation in UHV. ͓S0163-1829͑97͒02403-X͔

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Previously proposed models of monolayers of adenine and guanine, based on scanning tunneling microscopy and atomic force microscopy images, have been critically examined. We have applied molecular mechanics computer simulations to these models and, where appropriate, examined additional scanning tunneling microscopy data. These findings support the proposed adenine structure based on low-energy diffraction analysis and molecular mechanics but indicate that the structure of the guanine monolayer on graphite is different from those previously proposed. These findings indicate that the energy-minimized adsorbate stuctures of both adenine and guanine form a similar molecular configuration on both graphite and molybdenum disulfide surfaces. It is speculated that the formation of these structures may have had some prebiotic relevance.