Our Research

Basic research at the Institute for Green Science is focused on the design, development and understanding of TAML (Tetra-Amido Macrocyclic Ligand) activators and on their chemical and environmental applications.

Nanotubes

Scientific expertise: The Institute has led world-class research in the development of homogeneous oxidation catalysis. The Institute's team and its collaborators are experts in chemical design, organic and inorganic synthesis, kinetics and mechanism, spectroscopy, and analytical chemistry. Institute scientists are grounded in sustainability ethics and are keenly aware of the major environmental challenges confronting the chemical enterprise.

Collins design strategy: Iron-TAMLs were developed using an iterative design strategy created and led by Terry Collins, the Institute's founder and the Teresa Heinz Professor of Green Chemistry at Carnegie Mellon University. It took 15 years of research before Collins and his team succeeded in using Iron-TAML catalysts to mimic the natural enzymes he had targeted. The design protocol continues to guide catalyst improvements. There are now over 20 iron-TAMLs that differ in aggressiveness and lifetimes. The prototype is being produced commercially.

Iron-TAML catalysts: Iron-TAMLs are faithful synthetic replicas of peroxidase enzymes. They work at roughly the same rates, mirror at least some of the reactive intermediates, and follow related catalytic cycles. Such enzymes in living things activate hydrogen peroxide to oxidize organic compounds in ways that are reminiscent of combustion. Reactions akin to fire in water  occur when iron-TAML catalysts combine with peroxide to produce powerfully oxidizing intermediates that readily degrade oxidizable chemicals.

Targetable substrates: Hazardous chemicals degraded by iron-TAML-driven oxidations include numerous endocrine disruptors (EDCs), many persistent chlorinated pollutants (but not all), phenols (all of the many studied to date), dyes (almost all of the many studied thus far), chemical warfare agents, thiophosphate and organochlorine pesticides (all studied thus far), the smelly and colored compounds in pulp mill effluent, and the recalcitrant sulfur compounds in diesel and gasoline (leading to their improved extractability), among other things. Iron-TAML/peroxide has excellent potential for dye transfer inhibition and stain removal in laundry products. It rapidly kills pathogens in water including anthrax-like spores. By suitable choices of the catalysts and conditions, iron-TAML/peroxide can be employed to effect some selective oxidative transformations.

Practical parameters: Iron-TAMLs function at room temperature most naturally from pH 7 to any basic pH, including greater than 14. Usually the greatest rate is around pH 10. While iron-TAMLs all work at neutral pH, the pH of maximum rate is being lowered by the design of new iron-TAML generations for better performance under neutral conditions. Variants have been designed to work at acidic pHs. Iron-TAMLs do their work efficiently at miniscule concentrations, low μM to nM; typically needing only low H2O2 concentrations, μM to low mM.

We are conducting research aimed at the following practical applications:

Industrial

  • Purifying municipal waste water
  • Cleaning waste water from the wood, pulp and paper, chemical, pharmaceutical, oil, waste management, and other industries
  • Specialty chemical applications

Household

  • Preventing fabric dyes from transferring among garments while being washed
  • Selective bleaching of stains

Medical

  • Destroying pharmaceutical wastes in water
  • Disinfecting hospital areas more safely and effectively
  • Removing persistent molecules, especially endocrine disruptors, from water and the environment

Military/Battlefield

  • Rapid killing of biological warfare agents
  • Detoxification of chemical warfare agents
  • Decontaminating buildings and hardware
  • Purifying water