Interests

Our main research project focuses on the solvothermal synthesis of metal-organic open framework materials for the applications of catalysts, water purification, ion separation, and ion exchange. We synthesize germanium-, tin- and lead-based crystals, where the cationic metals are connected by one of a variety of linking anionic groups - oxygen, oxalate, phosphate or fluoride. Our interest in this area of the periodic table stems from the structural variety possible with these main group metals. The greater diversity of building blocks made from these metals has led to our discovery of new crystal structures, never known before. We named these materials "BING-n" for our previous affiliation, where BING denotes SUNY at Binghamton, and n for a particular structure type. Now we use "SLUG-n" to name a new series of single crystals recently synthesized at University of California, Santa Cruz. Below are several examples:

Layered transition metal Phenyphosphonate, SLUG-4

“Hydrothermal Synthesis and Characterization of a Layered Cobalt Phenylphosphonate, Co(PhPO₃)(H₂O)”,
Dalton Trans., 2006, 1574-1578.

The b-projection of one layer of SLUG-4. The c-projection of one layer of SLUG-4
We report the hydrothermal synthesis and characterization of a layered cobalt phenylphosphonate. Unlike most metal phosphonates reported to date, the structure was solved by single crystal X-ray diffraction (SC-XRD). Co (II) centres are hexa-coordinated by oxygen and the octahedra corner-share into a layer. The layers are capped by phenylphosphonate groups, where the phenyl groups define a hydrophobic bilayer region. The material was also characterized by powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA) and SQUID (superconducting quantum interference device) magnetometry. The material undergoes an antiferromagnetic transition at a relatively low Néel temperature of 4.0 K, while the Curie-Weiss temperature of –76.5 K reflects the low-dimensionality of the magnetic structure. The effective magnetic moment of 5.01m_B per Co²⁺ verifies a high-spin configuration and an octahedral coordination of the metal centres. This layered material was correctly predicted in the literature from powder data, adds to the structural diversity of the cobalt phosphonates, and may be useful as an intercalation or exfoliation compound.
Cationic Materials for Anion-Based Applications --- BING-5, one of two known cationic layered structures in the world

“Pb₃F₅NO₃, A Cationic Layered Material for Anion-Exchange”, J. Am. Chem. Soc., 2002, 124, 3966-3969.

SLUG-5 catalyzes a ketal formation reaction as a Lewis acid without the need for drying the solvent before the reaction or a nonaqueous medium such as toluene. The catalyst is heterogeneous and is completely recovered after the catalysis for reapplication.