International Tomography Center
Siberian Branch of Russian Academy of Sciences

Main achievements

Kiryutin, A. S., Sauer, G., Tietze, D., Brodrecht, M., Knecht, S., Yurkovskaya, A. V., Ivanov, K. L., Avrutina, O., Kolmar, H., Buntkowsky, G., Cover Feature: Ultrafast Single-Scan 2D NMR Spectroscopic Detection of a PHIP-Hyperpolarized Protease Inhibitor (Chem. Eur. J. 16/2019). Chemistry – A European Journal 2019, 25, 3966-3966.

Zhukov, I. V., Kiryutin, A. S., Yurkovskaya, A. V., Grishin, Y. A., Vieth, H.-M., Ivanov, K. L., Field-cycling NMR experiments in ultra-wide magnetic field range: relaxation and coherent polarization transfer. Phys. Chem. Chem. Phys. 2018, 20, 12396-12405. PCCP inside cover

Morozova, O. B., Ivanov, K. L., Time-resolved CIDNP of biologically important molecules. ChemPhysChem 2018, 20, 197-215.   Cover review

Pravdivtsev, A. N., Kiryutin, A. S., Yurkovskaya, A. V., Vieth, H.-M., Ivanov, K. L., Robust conversion of singlet spin order in coupled spin-1/2 pairs by adiabatically ramped RF-fields. J. Magn. Reson. 2016, 273, 56-64. Cover

Korchak, S. E., Ivanov, K. L., Yurkovskaya, A. V., Vieth, H.-M., Para-hydrogen induced polarization in multi-spin systems studied at variable magnetic field. Phys. Chem. Chem. Phys. 2009, 11, 11146-11156. Cover

The study of radical reactions that simulate the chemical path of DNA repair

In addition to the relatively slow enzymatic DNA repair processes to protect the genetic code, electronic vacancies in DNA can presumably be filled by transferring an electron from the protein environment. Such a “chemical pathway” of DNA protection can effectively prevent the formation of modified DNA segments. The radical radical reactions of guanine, the most easily oxidized base of the purine base, which simulate the process of "chemical repair" of DNA consisting in transferring an electron from aromatic amino acids tryptophan (Trp) and tyrosine to oxidized guanosine-5 'monophosphate (GMP) in four different protonated compounds States at pH values ​​from 1.3 to 13.3. The nucleotide radicals were generated photochemically, and radical reactions were detected by chemically induced polarization polarization of the nuclei (CIDNP) with a time resolution. It has been established that the reduction of GMP radicals by tryptophan proceeds more efficiently than tyrosine. The electron transfer rate constants were determined for all four possible forms of the GMP radical, from the radical dication to the radical anion, which differ in the degree of protonation of the purine base.

Determination of HFI constants 1H and 13C for short-lived radicals based on the detection of geminal spectra of CIDNP with microsecond time resolution

For the first time, a 13C spectrum was registered in the geminal recombination of the tryptophan radical cation in the photoreaction of electron transfer with a series of triplet-excited molecules in aqueous solutions for the first time using the CIDNP method with a microsecond time resolution. It is established that the electron spin density is localized mainly in the five-membered ring on carbon atoms C2, C3 and C9. The proposed method for determining the HFI constants from the CIDNP geminal spectra has been successfully tested on 1N and 13C. The CIDNP for photoreactions of reactions involving the neutral tyrosine radical with known HFI proton constants and some of the HFI 13C constants. The obtained values ​​of the HFI constants 1H and 13С for the neutral tyrosine radical and the tryptophan radical cation are consistent with the results of quantum mechanical calculations using the density function theory method for the optimized geometry of the indole ring, taking into account 35 water molecules in the first solvation shell.

Determination of magnetic resonance parameters of short-lived radicals from the spectra of geminal CIDNP and establishment of conditions for a linear relationship between the amplitude of CIDNP and the magnitude of HFI

A simple proportionality ratio between the amplitudes of the geminal CIDNP in diamagnetic products of radical reactions and their hyperfine interaction constants (HFI) at the radical stage of the reaction is theoretically derived. The limits of applicability of this relation are established; it is shown that it is quite accurate even with a small difference in the g-factors of the radical partners if the number of magnetic nuclei is sufficiently large.

Published: Kiryutin A.S., Ivanov K.L., Morozova OB, Yurkovskaya A.V., Fit H.-M., Pirogov Yu. A., Sagdeev R.Z. “The time-resolved CIDN method as a tool for the quantitative analysis of hyperfine interactions in short-lived radicals, ”Dokl. AN, 2009, 428 (3), 342-348.

Study of the effect of scalar interaction on coherent transfer of parahydrogen-induced nuclear polarization in an arbitrary magnetic field

Within the framework of the theoretical approach, the dependence of the effects of PHIP on the magnetic field was considered to describe the effects of parapolyhydrogen-induced nuclear polarization (IPHIP). Comparison of calculations with experimental data for PHIP of ethylbenzene, which occurs during the catalytic para-hydrogenation of styrene, has been carried out. For ethylbenzene, ideal agreement between theory and experiment was found, both for CH2 and CH3 protons, and for relatively weakly polarized aromatic protons. Calculations taking into account the real profile of the switching of the magnetic field and 10 coupled spins simulating the proton system of the ethylbenzene molecule showed perfect agreement with the experiment, while the calculations in the approximation of a sudden and adiabatic switching of the field did not agree well with the experimental data.

The results of studies of the dependence of the hyperpolarization of nuclear spins in hydrogenation with parahydrogen on the magnetic field were published in the journal Physical Chemistry Chemical Physics, where the article received the status of “Hot Paper”. The figure illustrating the content of this article is on the cover of the magazine.

Together with the Theoretical Spin Chemistry Laboratory, programs have been developed for the selection and optimization of parameters in experiments on the creation of long-lived singlet states by methods of adiabatic passage spin order conversion (APSOC) by radio frequency pulses.

The programs and their descriptions are available here

APG (Adiabatic Pulse Generator)