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Updated: Aug 21, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Protonation behaviour of chiral tetradentate polypyridines derived from alpha-pinene
Mathias Düggeli1, Tobias Christen, Alexander von Zelewsky
1Department of Chemistry, University of Fribourg, Pérolles, 1700 Fribourg, Switzerland.
Abstract:
Detailed protonation experiments of the [5,6]-pinenebipyridine molecule and the unsubstituted [4,5]- and [5,6]-CHIRAGEN[0] ligands in various solvents indicate a variety of structures of the protonated species. UV-visible and NMR measurements (including (15)N chemical shifts) show the transition from trans to cis conformation of [5,6]-pinenebipyridine upon protonation. The [4,5]-CHIRAGEN[0] ligand, in which the protonation sites of the nitrogen atom donors are at opposite sides of the molecule, behave essentially like two independent bipyridine moieties; this behaviour was monitored by UV-visible, CD and NMR spectroscopy (including (15)N data). In the case of the [5,6]-CHIRAGEN[0], a pocket of donor atoms provides a chiral environment for two protons per ligand.
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