Cover Picture

Abstract

The cover picture shows mesoscopic strands of highly fluorenscent perylene bisimide ± melamine assemblies as visualized by confocal fluorenscence microscopy. This technique does not only provide topological information such as related AFM or STM images, but truly shows the functionality of fluorescent optical networks of the present supramolecular system. The synthesis and structural investigations of the fluorescent mesoscopic superstructures is presented by F. Würthner et al. on p. 3871 ff. The author wishes to thank the BASF AG for kindly covering the costs for the cover picture

Hydrogen bond-directed aggregation of diazadibenzoperylene dyes in low-polarity solvents and the solid state

“…However, the lowbinding constant between pyridines and carboxylic acids precludes high degrees of polymerization in solution between dicarboxylic acid and dipyridine building blocks, which, up to now, limited this supramolecular synthon to applications in solid-state materials. Nevertheless, as shown recently, the binding constants of hydrogen bonds increase considerably with decreasing competition of the solvent with the receptor groups, which is given, for example, in aliphatic solvents (5). If additional weaker interactions such as -interactions or microphasesegregation (19,20) favorably contribute to the self-assembly process, then a hierarchical superstructure formation becomes likely in the solid state or even in dilute solution.…”

“…For most examples, this interaction relies on hydrogen-bonding, which is a directionalreversible interaction with adjustable binding strength (4, 5). Within the family of hydrogen-bonded systems, the association of carboxylic acids and pyridines has received special attention and includes work on defined molecular assemblies (6-9), supramolecular polymers and networks (4,5,(10)(11)(12)(13)(14), and hydrogen-bonded liquid crystals (15-18). However, the lowbinding constant between pyridines and carboxylic acids precludes high degrees of polymerization in solution between dicarboxylic acid and dipyridine building blocks, which, up to now, limited this supramolecular synthon to applications in solid-state materials.…”

“…T he current demand in highly ordered solid-state -conjugated materials for application in electronic devices, e.g., organic field-effect transistors and organic solar cells (1)(2)(3), constitutes a touchstone for supramolecular chemistry that stimulates several groups to synthesize receptor-functionalized chromophores and to control their solid-state organization by means of intermolecular forces (1)(2)(3)(4)(5). For most examples, this interaction relies on hydrogen-bonding, which is a directionalreversible interaction with adjustable binding strength (4,5).…”

“…A prerequisite for the formation of extended hydrogen-bonded polymers is an exact 1:1 stoichiometry between the precursors 1a,b and 2. Special care had to be taken in the preparation of the complexes, because even the slightest deviation from the exact stoichiometry results in low degrees of polymerization and will shift the equilibria toward short oligomers (5). Already in the course of preparing the complexes (refer to supporting information, which is published on the PNAS web site, www.pnas.org), an interesting observation was made after dissolving complex [1a⅐2] in methylcyclohexane.…”

Efficient deep-red light-emitting electrochemical cells based on a perylenediimide-iridium-complex dyad

“…[11][12][13] The solubility of the charged dyad 1 is additionally enhanced by a 2-ethylhexyl group at the terminal imide position. [14][15][16] As can be observed from density functional theory (DFT) calculations in Fig. 1 (see ESI for detailsw), the highest occupied (HOMO) and lowest unoccupied molecular orbitals (LUMO) are located on the PDI moiety, and the HOMO-LUMO energy gap (2.41 eV) is therefore dictated by the PDI unit.…”