Complexation of cobalt(II) at the upper rim of two new calix[4]arene/bipyridine-based podands

Introduction of one or two 2,2'-bipyridine units at the upper rim of the ca lix[4]arene platform was performed by means of the Wittig reaction. The res ulting alkenes were hydrogenated to give two new bipyridyl-based calixarene podands, which were studied as ligands for Co-II cation. The mono-bipyridy ldichlorocobalt complex was notably fully characterised by H-1-NMR and X-ra y crystal structure analyses, which confirmed the tetrahedral coordination mode involving the bipyridyl subunit and the two chlorine atoms around the cobalt centre.