A New Quadruply Bound Heterodimer DDAD·AADA and Investigations into the Association Process

Abstract

DDAD·AADA heterodimers based on the structures 8 and 9 have been synthesised and characterised. Solubility problems have been overcome through the introduction of a 2,6-dimethylphenyl substituent (8c), and association constants Kass have been determined by 1H NMR titrations. The Kass values obtained could be confirmed by osmometry, as could the association constants for other heterodimers. The Kass value increases when the acidity of participating N−H hydrogen atoms is enhanced. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)