title: Columnar liquid-crystalline dinaphthoperylenetetracarboxdiimides.
abstract: Although the double Friedel-Crafts acylation of arenes with ethyl chloroglyoxylate is hindered by the strongly deactivating effect of the first-entering glyoxylic substituent, the double reaction is successful with the reactive arene perylene under long reaction times and with concomitant ester hydrolysis. The reaction is regiospecific, giving the 3,9-regioisomer exclusively. This perylenylenediglyoxylic acid is condensed first with o-bromophenylacetic acid and then with α-branched alkylamines to yield the title compounds. Whilst the corresponding tetraalkyl esters only show monotropic mesophases, these diimides show enantiotropic columnar mesophases that can be maintained at room temperature if racemically branched alkyl chains of moderate size are used. A palladium-induced C-C bond migration during the build-up of the arene system leads to an isomeric side product of reduced symmetry that can be isolated by aggregation-controlled chromatographic separation. The HOMO and LUMO energies of the title compounds are considerably higher than those of established perylenetetracarboxdiimides.
authors: Centre de Recherche Paul Pascal, Centre National de la Recherche Scientifique and Université de Bordeaux, 115 avenue Schweitzer, 33600 Pessac (France), Fax: (+33) 556845600; Departamento de Química, Universidade Federal de Santa Catarina, 88040-900 Florianópolis, SC (Brazil).
authors: Marli
authors: M
authors: Ferreira
authors: Edivandro
authors: E
authors: Girotto
authors: Ahmed
authors: A
authors: Bentaleb
authors: Elizabeth A
authors: EA
authors: Hillard
authors: Hugo
authors: H
authors: Gallardo
authors: Fabien
authors: F
authors: Durola
authors: Harald
authors: H
authors: Bock
keywords: cyclization; fused-ring systems; liquid crystals; pi interactions; rearrangement