University of Texas, El Paso

September 6, 2019 – Fall Seminar

Time and Location: 12 Noon in Meyerhoff Chemistry Building, Room 120

Host: Dr. Zeev Rosenzweig

Fullerene Nanocontainers that Stabilize Unusual Atoms and Clusters Inside

Luis EchegoyenUniversity of Texas at El Paso, 500 Univ. Ave., El Paso Texas, 79968, USA Principal Author’s Principal echegoyen@utep.edu

For the past two years we have been involved in the synthesis and characterization of new Uranium-based endohedral fullerenes and have obtained X-Ray crystal structures for several of these compounds. Some are mono-uranium species, U@C_2n, while some are di-uranium compounds (see structure at the left), U₂@C_2n.¹ Very recently we isolated two new mono-uranium compounds that violate the Isolated Pentagon Rule  (IPR) with a C₇₆ and a C₈₀ cage possessing fused five-membered rings (pentalenes) on their surfaces.² Still other endohedral structures are much more interesting and totally unanticipated, with formula U₂X@C_2n, where X= C, O, S or N and 2n= 72, 78 or 80, which reveal interesting metal-cage interactions and totally unprecedented clusters trapped inside. Some of the carbide compounds have been crystallized and the encapsulated U₂C cluster (in U=C=U@C₈₀) exhibits unprecedented bonding with totally unanticipated properties (see structure to the right).³

Finally, we have found that bis-porphyrin capsules exhibit exquisitely selective supramolecular binding for several of these uranium-based endohedral fullerene compounds.⁴

The synthesis, purification and characterization of these interesting endohedral fullerenes will be presented and discussed, along with very recent results about uranium-based endohedrals.