Self-association of branched and dendritic aromatic amides

Several branched and dendritic aromatic amides have been obtained by reacting tris(4-aminophenyl)methane 3 either with aryl iodide 1 in a Pd-catalysed carbonylation or with carboxylic acids in the presence of the coupling agent triphenyl phosphite. Nonpolar aromatic substituents and solubilising groups at the periphery ensured that the resulting oligoamides were soluble in chloroform, whereas amide groups in the structural centre of the molecules accounted for strong self-association through hydrogen bonding in solution as evidenced by H-1 NMR and vapour-pressure osmometry data. An alternative approach towards branched aramides is also presented which was based on the self-assembly of 1,3,5-tris(4,5-dihydroimidazol-2-yl)benzene 12 and various (amido)carboxylic acids.