Self-Assembly and Host–Guest Interactions of Pd<sub>3</sub>L<sub>2</sub> Metallo-cryptophanes with Photoisomerizable Ligands
Edward Britton, Richard J. Ansell, Mark J. Howard, Michaele J. Hardie
Abstract
High Resolution Image Download MS PowerPoint Slide New photoswitchable pyridyl-azo-phenyl-decorated tripodal host ligands (L az ) that belong to the cyclotriveratrylene family have been synthesized, and their photoswitching behavior and crystal structures determined. The latter includes a remarkable 7-fold Borromean-weave entanglement of π–π stacked layers. Trigonal bipyramidal {[Pd(en)] 3 (L az ) 2 } 6+ metallo-cryptophanes (en = ethylenediamine) were formed from these and a previously known pyridyl-azo-phenyl-decorated tripodal host ligand. These coordination cages dissociate at low concentrations and are less robust to photoswitching of the L az ligands than were previously reported Ir(III)-linked metallo-cryptophanes with similar ligands, reflecting the greater lability of the Pd–N bonds. The {[Pd(en)] 3 (L az ) 2 } 6+ cages all act as hosts, binding octyl sulfate anions, or N -[2-(dimethylamino)ethyl]-1,8-naphthalimide in a dimethyl sulfoxide solution.