Ilya G. Shenderovich
Main scientific interest: Hydrogen bond and proton transfer:
H-bond is a specific interaction involving two (in some cases three) electronegative atoms and a proton. A moderate strength (up to 200 kJ/mol, that is intermediate between the covalent and van der Waals interactions) and the directionality are the main features of H-bond responsible for a variety of phenomena in physics, chemistry and biology. Among these phenomena are boiling and melting points of water, structure of ice, hydrophobic/hydrophilic interactions, proton transfer, molecular recognition and enzymatic catalysis.
Fundamental aspects of H-bond in condensed matter:
Understanding geometry of intramolecular and intermolecular H-bonds and proton transfer in model systems is a mandatory step before getting success in application relevant cases. In collaboration with our colleagues we combine advantages of different spectroscopic and quantum mechanical methods to go ahead.
H-bond networks are of great importance for all kinds of polymers. Although amorphous, polymers possess a short-range order and often contain local crystallinity. The local structure and overall mechanical properties, water content and proton conducting are affected by H-bond networks in polymers. H-bond networks in active sites of enzymes define the catalytic activity. Depending on specific problem we use either isotopically enriched polymers or probe-molecules.
Towards NMR of nanostructures:
Morphology and chemical reactivity of nanostructures are a challenge to study. We care studying high-ordered silica based porous materials of SBA and MCM type. In contrast to polymers, these materials are short-range disordered but possess a long-range order. The surface reactivity, the dynamics of adsorbed molecules and the local structure are the key problems we are interesting in.
Isotopically enriched species and materials:
Synthesis of problem-oriented isotopically enriched probe-molecules and materials does more than just save money. It helps us to ask and answer new questions.
Specific scientific interests:
“Isolated” H-bonded clusters in condensed matter
In the simplest case one deals with a few H-bonds forming an “isolated” cluster. Varying the medium, counterion and using H/D isotope substitution one describes the H-bonds and their mutual interactions in details.
H-bond networks in polymers
If medium effect on geometry of an “isolated” cluster is known, one uses the cluster as a probe to inspect H-bond networks in complex systems. The short-order structure and proton transfer are the main research problems.
Functional H-bonds in the active sites of enzymes
Isotopically enriched NMR-sensors are used to study the catalytic mechanisms of enzymes.
H-bond on a solid surface
Surface chemistry is often affected by surface hydroxyl groups. The potential chemical reactivity of these groups, their density and distribution are of the main interest. These data provide information about the local surface structure and the bulk structure.
Encapsulation of polymers into mesopores
Inspired by prospects of engineering novel materials for bio- and nanotechnology using the immobilization of polymers, and proteins on solid surfaces, we propose a strategy intended to facilitate the application of NMR for the analysis of host-guest interactions in such systems at the molecular level. In order to overcome the major weakness of NMR – its intrinsically low sensitivity as compared to many other analytical techniques – we are aiming to elaborate two independent, complementary approaches consisted in doping of either the guest or the host with NMR-sensors sensitive to noncovalent interactions.
Main research methods:
NMR in liquefied gases down to 100 K
CDF3/CDClF2 mixture remains liquid down to 100 K. Water precipitates from the mixture at 170 K leaving a perfectly aprotic solvent suitable to study “isolated” H-bonded clusters. The dielectric constant of the mixture increases from 20 to 40 upon cooling from 170 K to 100 K. That makes possible to simulate the medium effect on the H-bond structure.
Temperature variable NMR in the solid state
Whether X-ray or NMR suits more to elucidate the structure of crystals is a debatable question. For amorphous materials NMR is out of competition. 1H and 15N NMR under magic angle spinning and static conditions are employed to inspect H-bonds in crystalline and amorphous solids.
Qualitative analysis using DFT methods
One can hardly overestimate advantages provided by quantum mechanical methods for studying molecular interactions. One can easily overestimate the validity and precision of the obtained results.