title: Homo- and heteroassemblies of lactim/lactam recognition patterns on highly ordered pyrolytic graphite: An STM investigation.
abstract: The 2D assembly of phthalhydrazide 1 and aminopyrimidine 2 derivatives equipped with C16 and C8 alkyl chains, respectively, on highly ordered pyrolytic graphite (HOPG) was studied by scanning tunneling microscopy. Well-defined, rather complex surface layer patterns emerge resulting from a delicate balance of (self-) complementary (strong) hydrogen bonds and van der Waals force-driven ordering of the alkyl substituents on the HOPG surface. The four different compounds and their 1:1 mixtures yield seven different 2D structures. Phthalhydrazide offers in principle three tautomeric forms, with the lactim/lactam being the most stable. Depending on the solvent, different morphologies can be obtained. In one case, the special self-assembly of achiral 1a leads to a 2D chiral packing with the left- and right-hand motifs present in different domains. We assume that pure 1a is expressed in its lactim/lactam form, whereas in a 1:1 mixture with 2a it switches to the bislactam form. These features display a process of dynamic diversity generation through tautomerism resulting in different nanostructures in response to environmental parameters.
authors.affiliation: Organische Chemie III/Makromolekulare Chemie der Universität, Albert-Einstein-Allee 11 D-89069 Ulm, Germany.
authors.forename: Ahmed
authors.initials: A
authors.lastname: Mourran
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ziener
authors.forename: Martin
authors.initials: M
authors.lastname: Möller
authors.forename: Maurizio
authors.initials: M
authors.lastname: Suarez
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Lehn