Research in our laboratories is focussed in three main areas. The synthesis of analogs for certain metal cluster, active sites, important in enzymatic catalysis. The design and synthesis of supramolecular assemblies for use as molecular devices. The discovery and use of metal complexes in medicine and particularly cancer treatment. The enzyme nitrogenase uses a unique cluster, with a Fe7MoS9 core, to catalyze the life sustaining , multielectron, reduction of atmospheric dinitrogen to ammonia. We are actively pursuing research that involves the synthesis , structural characterization and reactivity of synthetic Fe/Mo/S clusters designed as models for nitrogenase. To date we have obtained a multitude of new clusters, some of which are catalytically active in the reduction of nitrogenase substrates. The ultimate aim of this research is to develop synthetic, nitrogen-fixing catalysts that function at ambient temperatures and pressure and may be applied directly to crops in the field to produce ammonia in situ. Ammonia is a very important fertilizer and presently is obtained commercially by the energy demanding, environmentally unfriendly Haber-Bosch process.
The second major area of research we have been developing in recent years concerns the synthesis of inorganic supramolecules. A special class of such molecules are certain ditopic receptors that are capable of transporting biologically important molecules (aminoacids, oligopeptides and neurotransmitters) across lipid membranes. These molecules are expected to be very useful in the delivery of certain drugs across membranes. At present, drug delivery is one of the major concerns of the pharmaceutical industry. In addition to carriers other supramolecules are sought that contain specific subunits and will serve as elementary molecular devices. Such devices hold promise as chemical sensors, as facilitators of photochemically induced charge separation, electron storage and multisite molecule activation.
The tetrathiomolybdate anion, MoS42-, has been found a copper antagonist and consequently a very effective antitumor agent. Ongoing research with this molecule, which presently is being evaluated by the FDA, is aimed at an understanding of the mode of action and subsequently the design and synthesis of other similarly effective, cancer-curing, complexes.
Smith M.C.; Xiao, Y.; Wang, H.; George S.J.; Coucouvanis, Koutmos, M.; Sturhan , W.; Alp, E.E.; Zhao, J.' Cramer, S.P. . Normal Mode Analysis of FeCl4 and Fe2S2Cl4- via vibrational Moessbauer Resonance Raman and FT- I R Spectroscopy. Inorg. Chem.
Markos FeMoCu clusters. "Metal Clusters as Ligands II" Inorg. Chem. 2006, 43, in Press Han, J.; Coucouvanis D. Synthesis and structure of the organometallic Mfe 2 (m 3 -S) 2 clusters (M=Mo or Fe). J. Chem. Soc. Dalton Trans 2005
Quagraine, E.K.; Coucouvanis, D.; Georgakaki, I. Cu antagonism and the angiostatic Function of the MoS 4 2- Ligand. Reactivity and Kinetic Studies of (NH4 )2 MoS4 in acidic Aqueous Solution in the Presence and Absence of Cu2+ J. Inorg. Biochem.
Kalyvas, H.; Coucouvanis, D. Synthesis and reactivity of a new octanuclear iron-sulfur nitrosyl cluster. Inorg. Chem.
Yuming Xiao, Markos Koutmos, David A. Case, Dimitri Coucouvanis, Hongxin Wang and Stephen P. Cramer Dynamics of an [Fe 4 S 4 (SPh) 4 ]2- cluster explored via IR, Raman, and nuclear resonance vibrational spectroscopy (NRVS)-analysis using 36s substitution, DFT calculations, and empirical force fields , Dalton Trans., 2006