Dinuclear triple-stranded helicates from rigid oligo-p-phenylene ligands:: Self-assembly and ligand self-recognition

The rigid rod oligo-p-phenylene type dicatechol ligands 1-3H(4) form dinuclear triple-stranded helicates M-4[(1-3)(3)Ti-2] in the presence of appropriate counterions (M = Li, Na, K, or NH4). Studies on the self-recognition ability of the ligands show that self-recognition takes place if mixtures of ligands with significantly different sizes (1/2) are used in coordination studies, or if ligands are used which do not match for geometric reasons (1/4). Mixtures of ligands with a similar geometric preference (2/5) do not lead to self-recognition, but instead give mixtures of hetero- and homoleptic complexes. ((C) Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002).