Equipping metallo-supramolecular macrocycles with functional groups: assemblies of pyridine-substituted urea ligandsElectronic supplementary information (ESI) available: Experimental details and additional information on the ligands and complexes. CCDC 864202-864209. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2dt30190c

• Main Authors: Troff, Ralf W, Hovorka, Rainer, Weilandt, Torsten, Lützen, Arne, Cetina, Mario, Nieger, Martin, Lentz, Dieter, Rissanen, Kari, Schalley, Christoph A
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt30190c

A series of di-( m -pyridyl)-urea ligands were prepared and characterized with respect to their conformations by NOESY experiments and crystallography. Methyl substitution in different positions of the pyridine rings provides control over the position of the pyridine N atoms relative to the urea carbonyl group. The ligands were used to self-assemble metallo-supramolecular M 2 L 2 and M 3 L 3 macrocycles which are generated in a finely balanced equilibrium in DMSO and DMF according to DOSY NMR experiments and ESI FTICR mass spectrometry. Again, crystallography was used to characterize the assemblies. Methyl substitution in positions next to the pyridine nitrogen prevents coordination, while the other ligands form small metallo-supramolecular macrocycles. The incorporated urea carbonyl groups provide hydrogen bonding sites which converge towards the center of the assemblies. Metallo-supramolecular macrocycles with dipyridyl urea ligands that bear hydrogen bond acceptors and donors for molecular recognition are synthesized and characterized.