Open AccessSynthesis, structure, and properties of oligo-tridentate ligands; covalently assembled precursors of coordination arrays
Author(s) -
Garry S. Hanan,
Ulrich S. Schubert,
Dirk Volkmer,
Emmanuel Rivière,
JeanMaríe Lehn,
Nathalie Kyritsakas,
Jean Fischer
Publication year - 1997
Publication title -
canadian journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.323
H-Index - 68
eISSN - 1480-3291
pISSN - 0008-4042
DOI - 10.1139/v97-020
Subject(s) - chemistry , crystallography , supramolecular chemistry , stille reaction , moiety , ligand (biochemistry) , crystal structure , stereochemistry , polymer , organic chemistry , biochemistry , receptor
Oligo-tridentate ligands based on alternating pyridines and pyrimidines were synthesised by Stille-type carbon–carbon bond-forming reactions. The terpyridine-like sites are designed to coalign upon metal complexation, giving rise to organized and rigidly spaced metal ions. Peripheral functionalization of the basic bis-tridentate framework was explored. The heterocycles in the ligands are in an all-trans conformation about the interannular bonds as indicated by comparison of their 1 H NMR spectra. An X-ray crystal structure analysis of the nonchiral tris-tridentate ligand 2a reveals a helical structure in the solid state. The seven heterocycles form a helical structure with resulting overlap of the terminal pyridines. Their centroid-to-centroid distance is 4.523 Å with 38.8° between the planes. NMR investigations support a helical conformation in solution as well. Electrochemical and UV absorption measurements indicate that the LUMO resides on the pyrimidine moiety of the ligands. Keywords: nitrogen-containing ligands, Stille coupling, helical structure, supramolecular chemistry.