Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday Large molecules adsorbed on surfaces can be analyzed by scanning tunneling microscopy (STM) under various environmental conditions: on a dry surface in air or vacuum, and at the solid-liquid interface. However, can measurements under dissimilar conditions be compared, e. g., when sample A was studied at the solid-liquid interface and sample B in a dry environment? Only rarely can the same substance be examined with more than one approach, since completely different set-up and preparations are necessary. Furthermore, few substances are suitable for several methods of sample preparation and characterization. We have chosen a large, flexible, nonplanar molecule, namely an alkoxy-substituted second-generation dendritic compound with a chiral core unit, which is peculiar for its −hourglass× conformation. The assembly properties have been explored by STM both in solution-cast self-organized monolayers (SOMs) and multilayer films, as well as at the solid-liquid interface. The complexity and limits of the three approaches applied to our hourglass-shaped dendritic compound are discussed. Depending on the approach and environmental conditions, several quality levels of image resolution could be achieved; measurements carried out at low temperatures led to highest resolution on the aromatic parts of the molecule. A comparison of equally sized images obtained under these varying conditions reveals not only different packing arrangements, but also spots of unlike shape. Therefore, when the approach, preparation, and/or environmental conditions are not the same, STM measurements of different compounds have to be compared with greatest care.
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