ABSTRACT
A novel cavity-containing porphyrin catalyst based on a previously reported clip architecture, substituted on the outer face with urea terminated tails, has been synthesized, and its properties toward the epoxidation of polybutadiene have been studied. It is shown that the presence of the urea tails provides efficient shielding of the manganese porphyrin against destruction and selectively directs the oxidation process to the inside of the catalyst cage, allowing for processive oxidation of a polymer substrate without the need of an additional axial ligand.
Subject(s)
Butadienes/chemistry , Elastomers/chemistry , Porphyrins/chemistry , Catalysis , Models, Molecular , Molecular Structure , Oxidation-Reduction , Urea/chemistryABSTRACT
The threading behavior of a zinc analogue of a previously reported processive manganese porphyrin catalyst onto a series of polymers of different lengths is reported. It is demonstrated that the speed of the threading process is determined by the opening of the cavity of the toroidal porphyrin host, which can be tuned with the help of axial ligands that coordinate to the metal center in the porphyrin.
