Rybak-Akimova Research Group

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Dinuclear metallocomplexes

While attaching receptor sites to transition metal complexes might be synthetically challenging, another entryway into ditopic substrate binding is provided by self-assembled dinuclear complexes. In this case, coordination of the substrate to two metal ions accounts for strong and selective recognition. As an example, an unusual bidentate urea binding to oxo-bridged bis-iron(III) complex has been demonstrated. This type of urea coordination yields strong complexes (K=650 M^-1 in aqueous acetonitrile) and is accompanied by significant changes in visible spectra, which opens up the possibilities for selective detection of biomolecules containing urea fragments (nucleic bases, biotin, uric acid, etc.). Collaborative studies with F. Meyer (University of Göttingen, Germany) on mechanisms of urea binding to a dinuclear nickel model complex reveal relatively weak (K=4 M-1), fast and reversible coordination of urea to both nickel(II) ions.

Our recent results on urea binding modes also contribute to understanding the mechanism of urea hydrolysis by a bis-nickel enzyme urease. Although this is one of the most efficient enzymes, its mechanism is still poorly understood. In addition to model studies, we are currently studying the kinetics of urease enzyme, in order to identify mechanistically important substrates and inhibitors.