Threading of various ‘U’ shaped bidentate axles into a heteroditopic macrocyclic wheel via NiII/CuII templation

Abstract

The threading of ‘U’ shaped bent axles having diverse functionalities (Axle1–Axle10) is investigated by using a heteroditopic amido–amine macrocyclic (MC) wheel via Ni^II or Cu^II metal ion templation. These bent shaped axles are the derivatives of 4,4′-substituted 2,2′-bipyridine, which are composed of various terminal groups like alkene, alkyne, bromide, hydroxyl and azide. Such metallo [2]pseudorotaxanes are well characterised by ESI-MS, EPR and FT-IR spectroscopic studies, UV-Vis absorption studies, elemental analysis and single-crystal X-ray diffraction studies wherever possible. Experimental evidence supports 1 : 1 : 1 ternary complexation between MC, the metal ion and axle. The single crystal X-ray structures of three Cu^II templated ternary complexes (PR1′, PR3′ and PR7′) show the penta-coordination arrangement around the templating metal ion. Interestingly, judicious selection of chemical functionalities in the complementary wheel and axle components enables to show the existence of various covalent and non-covalent interactions.