Phenanthroline-containing rotaxanes

Molecular motion based on the electrochemical-induced ligand substitution reaction has been reported in a copper(I) rotaxane (Figure 37). This rotaxane is composed of a 2,9-diphenyl-l,10-phenanthroline-containing cyclic poly ether ring, a tetraphenylmethane-stoppered molecular string that contains another 2,9-disubstitnted phenanthroline chelate... 

The Cu / phenanthroline strategy to prepare novel supramolecular architectures, as exemplified by the synthesis of a simple catenane. Sau vage, J.-P. "Transition Metal-Containing Rotaxanes and Catenanes in Motion Toward Molecular Machines and Motors." Acc. Chem. Res., 31,611-619 (1998). 

Figure 232. Copper(I)-templated synthesis of Cu(I)-complexed [2]-rotaxane 96 whose thread contains a terpyridine and a phenanthroline chelate.

The rotaxane 13 + [the nomenclature of the rotaxanes described here is 13W n+, where N refers to the coordination number of the metal (4 or 5) and n to its charge] synthesized herein is composed of two subunits a macrocycle and a molecular thread (Fig. 11). The 33-membered macrocycle Mt33 [18, 19] contains two different coordinating sites a terpyridine moiety and a 1, 10-phenanthroline one. 

Photochemically controlled shuttling of the macrocycle component by a sacrificial mechanism has also been obtained in a rotaxane containing a phenanthroline and a terpyridine unit in its dumbbell-shaped component, a phenanthroline ligand in the macrocycle, and a Cu(I) center coordinated by... 

Zn was selected because its geometrical requirements are approximately those of Cu, but its higher charge will alter more the n-accepting ability of the complexed phenanthrolines. Thus metal free [2]-rotaxane 15 (PF5 ) was reacted with Zn(0Ac)2<2H20 and after chromatographic purification the zinc(II) [2]-rotaxane (183+(PF5")3) was obtained in 35% yield. As shown by ES-MS, this material contained traces of copper rotaxane 122+(PF6 )2 and free rotaxane 15 (PF6 ) which could not be removed by chromatography. 

---