title: 2D self-assembly of fused oligothiophenes: molecular control of morphology.
abstract: We report the synthesis and properties of two π-functional heteroaromatic tetracarboxylic acids (isomeric tetrathienoanthracene derivatives 2-TTATA and 3-TTATA) and their self-assembly on highly oriented pyrolytic graphite. Using scanning tunneling microscopy at the liquid-solid interface we show how slight geometric differences between the two isomers (position of sulfur in the molecule) lead to dramatic changes in monolayer structure. While 3-TTATA self-assembles exclusively in a highly ordered porous network via dimeric R(2)(2)(8) hydrogen-bonding connection (synthon), 2-TTATA is polymorphic, forming a less ordered porous network via R(2)(2)(8) synthons as well as a close-packed network via rare tetrameric R(4)(4)(16) synthons. Density functional theory calculations show that the self-assembly direction is governed by the angle between the carboxylic groups and secondary interactions with sulfur atoms.
authors.affiliation: Department of Chemistry and Center for Self-Assembled Chemical Structures, McGill University, 801 Sherbrooke Street West, Montréal, Québec, Canada H3A 0B8.
authors.forename: Chaoying
authors.initials: C
authors.lastname: Fu
authors.forename: Federico
authors.initials: F
authors.lastname: Rosei
authors.forename: Dmitrii F
authors.initials: DF
authors.lastname: Perepichka
mesh_terms: D003198:Computer Simulation; D003460:Crystallization / Q000379:methods*; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D036103:Nanotechnology / Q000379:methods*; D010316:Particle Size; D013499:Surface Properties; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D046911:Macromolecular Substances; D013876:Thiophenes