1. Department of Chemical Engineering and Center for Molecularly Engineered Materials, University of Notre Dame, Notre Dame, Indiana 46556, Materials Characterization and Catalysis Technology Group, ExxonMobil Research and Engineering, PO Box 480, Paulsboro, New Jersey 08066, and Corporate Strategic Research, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, New Jersey 08801