Rybak-Akimova Research Group

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Department
Tufts U.

Introduction:

The main theme of our research is understanding the selectivity of small molecule binding and activation with transition metal complexes. The group focuses on two approaches to this problem which are inspired by nature: (1) introducing specific substrate binding sites into transition metal platforms, thus mimicking selective substrate binding at the active sites of the enzymes (design of transition metal containing molecular tweezers for selective binding and activation of polyfunctional substrates); (2) investigating the detailed mechanisms of small molecule activation at the metal centers in synthetic complexes that model the active sites of metalloenzymes, and specific reactivities of transient metal-containing intermediates formed in these processes. Additionally, a novel macroscopic phenomenon in dioxygen chemistry, spatial pattern formation in catalytic oxidation of substrates with dioxygen at a liquid/gas interface, is being investigated.

The research projects encompass the fields of coordination chemistry, bioinorganic chemistry, and supramolecular chemistry. The potential applications of our results include design of new selective reagents and catalysts, design of selective receptors for sensors and separation processes, drug design, and design of new materials via self-assembly and self-organization.

The students are trained in synthetic methods (organic and inorganic synthesis), including manipulation of air-sensitive compounds, as well as in a variety of physical methods of characterization of organic and coordination compounds (NMR, EPR, IR, UV-Vis spectroscopy, X-Ray crystallography), and in thermodynamic and kinetic measurements. Molecular modeling is also used in our research.

Selective (multipoint) binding (and activation) of polyfunctional substrates:

Metal ion containing multicenter receptors offer several advantages over purely organic hosts, such as: (1) metal ions affect binding, improving selectivity; (2) metal ions are reactive sites, allowing for selective substrate transformations; (3) reactivity of the metal center can be altered, e.g., by changing the oxidation states; (4) the shape of the receptor molecule can be regulated via reversible reactions at the metal center.

Molecular Tweezers

Dinuclear metallocomplexes

Investigations on the detailed mechanisms of oxygen and peroxide activation at the metal centers

Kinetic and mechanistic studies

Mononuclear iron(II) complexes with pentadentate macrocycles

Activation of nitrous oxide with coordinatively unsaturated molybdenum complexes

Spontaneous pattern formation in reaction-diffusion systems containing dioxygen