Non-covalent Interactions Laboratory

Research

Non-covalent Interactions

Non-covalent interaction is the common name for interactions the formation of which does not result in the sharing of the electron density. The energy of non-covalent interactions is much less than the energy of covalent interactions. However, due to their prevalence, non-covalent interactions play a fundamental role in synthesis, catalysis, crystal engineering, electrochemistry, molecular recognition, biology, materials science, etc. For example, many catalytic processes can go through transition states and intermediate stages stabilized by non-covalent interactions determine the selectivity and further direction of the reactions. In addition, reactions catalyzed by metal complexes often occur due to non-bonded interactions between the initial material and the catalyst. Thus, understanding the nature of these weak interactions may turn out to be an important step in the development of new effective synthetic catalysts.

All known to date non-covalent interactions can be classified into four groups: electrostatic, Van-der-Waals, hydrophobic, and π-interaction.

Electrostatic interactions include hydrogen bonding, σ-hole interactions (halogen, pnictogen, halcogen, aerogen, tetrel etc.), agnostic interactions and ionic interactions.

• Hydrogen bondingoccurs when a hydrogen atom bonded to a electronegative atom (fluorine, oxygen, nitrogen, etc.) comes to proximity with another electronegative atom. These bonds are usually stronger than normal dipole-dipole and dispersion forces, but weaker than true covalent and ionic bonds. Hydrogen bonding largely determines the properties of such biologically important molecules as proteins and nucleic acids. In particular, secondary structure (e.g., α-helices, β-folds) and tertiary structure in proteins, RNA, and DNA molecules are stabilized by hydrogen bonds.

• Halogen bonding occurs due to an attractive interaction between the electrophilic region of the halogen atom (the so-called σ-hole) and the nucleophilic region (such as an unshared electron pair) in another molecule. This interaction is widely used in such fields as supramolecular chemistry, crystallography, and liquid crystal fabrication.

• Agostic interaction is the interaction of a coordinationally unsaturated transition metal with the C-H bond, when the two electrons involved in the C-H bond move to the empty d-orbital of the transition metal, resulting in the formation of a three-center two-electron bond. Many catalytic transformations, such as oxidative addition and reductive elimination, presumably involve agostic interactions.

• Ionic interaction is realized by electrostatic attraction between anions and cations. The most important features of ionic bonding from other types of chemical bonding are its non-directional and non-saturated nature. That is why crystals formed by ionic bonding tend to have various dense packings of the corresponding ions.

Van-der-Waals interactions include dipole-dipole, dipole-induced dipole, and dispersive interactions.

• Dipole-dipole interactions occur when two polar molecules interact with each other through space. In this case, the partially negative part of one of the polar molecules is attracted to the partially positive part of the second polar molecule.

• The interaction between a dipole and an induced dipole occurs when a polar molecule induces a dipole in an atom or in a non-polar molecule, disturbing the arrangement of electrons in the non-polar member.

• Dispersion interaction is caused by the interaction of atoms and molecules with each other due to their own or mutually induced dipole moments. The instantaneous charge distribution of one atom or molecule, characterized by an instantaneous dipole moment, induces an instantaneous dipole moment in another atom or molecule

Hydrophobic interactions are the attraction between non-polar particles in water (or other polar solvents), which is caused by the thermodynamic disadvantage of water contact with non-polar substances. Hydrophobic interaction takes part in the formation of the tertiary structure of proteins and provides molecular recognition in some supramolecular guest-host complexes. It manifests itself in the formation of micelles and other structures in surfactant solutions.

π-interactions are a type of non-covalent interactions in which an electron-rich π-system can interact with a cation, anion or other π-system. Non-covalent interactions with π-systems are crucial for biological processes such as protein-ligand recognition.

Projects

Organometallic Chemistry

Although lithium derivatives of 1,8-bis(dimethylamino)naphthalene (DMAN) have been used for quite a long time as a tool for the creation of new supebases of proton sponges series, the specifics of their formation, structure, and reactivity remain poorly understood. At the same time, DMAN derivatives of other metals are not known at all. In order to fill such an unfortunate gap in the chemistry of superbases, the following projects are being implemented in our laboratory:

• Direct lithiation of DMAN and related compounds in order to synthesize their hardly available meta- and peri-derivatives.

Antonov, Yakubenko Synthesis 2020	Antonov et al. J. Organomet. Chem. 2020

• Synthesis and reactivity of organocopper and organoboron derivatives of DMAN.
• Steric activation of dimethylamino group in the synthesis of fused heterocycles.

Antonov et al. Molecules 2020

Today, special attention is paid to the development of functional materials, in particular polymers with superbasic properties. Within this direction our laboratory implements the following projects:

• Development of superbasic polymeric materials with different kinetic basicity - polymeric catalysts and proton conducting polymers.
• The production of materials based on hydride sponges for the storage of hydrogen.

The modern approach to the study of non-covalent interactions requires the development of methods for the synthesis of novel donors and acceptors, which will make it possible to understand the periodicity of changes in the interaction strength depending on the nature of the elements that make up the binding participants, as well as allow the use of new, more sensitive methods of study. Within the framework of this direction our laboratory implements the following projects:

• Development of methods for the synthesis of organic acids, oxides and selenides of group 15 elements.
• Preparation of chiral selenophosphoric acids and study of their catalytic activity (in collaboration with the University of Regensburg).

Quantum Chemistry

Quantum chemistry methods are based on the principles of quantum mechanics applied to molecular systems. The solution of the quantum chemical problem is reduced to the numerical solution of the Schrödinger equation using various approximations. Modern methods require significant computational resources, therefore calculations are carried out using powerful computational clusters.

Spectroscopy (IR, NMR) and quantum chemistry methods are complement each other. Calculations are used to explain experimentally observed phenomena, to predict experimental results, or to model impossible experiments.

In our laboratory, we solve the problem of finding correlations between the spectral parameters of complexes with hydrogen bonds and their geometry and energy.

Tupikina et al. J. Comput. Chem. 2019	Tupikina et al. Phys. Chem. Chem. Phys. 2020	Tupikina et al. J. Comput. Chem. 2021

We have proposed a new method for quantum-chemical diagnostics of the features of the outer electronic shell of atoms, molecules and complexes with hydrogen bonds. The keystone of this approach is usage of the ³He atom as a probe particle. Our method allows visualization of both proton-acceptor and proton-donor properties of molecular systems and has advantages over conventional methods (MESP, ELF).

Tupikina et al. J. Phys. Chem. A 2017	Tupikina et al. J. Comput. Chem. 2018	Tupikina et al. J. Comput. Chem. 2020

One of the directions of quantum-chemical research in our laboratory is the study of the features of the electronic shells of fragments of biological molecules (amino acids, proteins, enzymes). In particular, prediction of possible directions of nucleophilic attack, study of the influence of additional hydrogen bonds with solvent molecules or side chains of a biological molecule on its reactivity.

NMR Spectroscopy

The nuclear magnetic resonance technique (NMR) is based on the registration of resonant absorption of radio frequency energy by a sample placed in a uniform magnetic field. Radiation is absorbed by nuclei with a nonzero magnetic moment (¹H, ¹³C, ¹⁹F, ³¹P, etc.). NMR spectroscopy is the most important method for determining the structure of organic molecules.

In our laboratory, experimental NMR spectroscopy is used to study the properties of various systems with hydrogen and halogen bonds. In particular, we are working on the development of a methodology for interpreting the experimental values of ³¹P chemical shifts as descriptors of the energy and geometry of the hydrogen bond. Establishing quantitative relationships between the ³¹P chemical shift is complicated (and therefore becomes more curious :)) due to the fact that the phosphorus nucleus is extremely sensitive to many additional factors.

Tupikina et al. J. Phys. Chem. A 2017	Tupikina et al. J. Comput. Chem. 2018	Tupikina et al. J. Comput. Chem. 2020

To obtain high-resolution NMR spectra at low temperatures (up to 100 K), we use and refine a unique technique — we use mixtures of liquefied freon gases as solvents. Under such conditions, the processes of proton and molecular exchange are slowed down and signals of complexes of various stoichiometric and isotopic compositions are resolved on the NMR spectra.

Mulloyarova et al. Phys. Chem. Chem. Phys. 2018

Our grants

• RFBR grant 20-03-00231 «Media effects on proton position in hydrogen bond: local field and specific solvation» (Prof. Dr. P. Tolstoy).
• RFBR grant 20-33-70205 «Sterically assisted activation of dialkylamino group in the synthesis of fused nitrogen heterocyles: experimental and theoretical challenge» (Prof. Dr. A. Antonov).

Publications

Selected publications 2019–2020

E.Yu. Tupikina, P.M. Tolstoy, A.A. Titova, M.A. Kostin, G.S. Denisov, “Estimations of FH···X hydrogen bond energies from IR intensities: Iogansen's rule revisited”, J. Comput. Chem. 41 (2021) published online. DOI: 10.1002/jcc.26482

In this work the possibility of using the IR intensity of the stretching vibration ν_s of proton donor group for estimation of hydrogen bond strength was investigated. For a set of complexes with FH···X (X = F, N, O) hydrogen bonds in the wide range of energies (0.1–49.2 kcal/mol) vibrational frequencies ν_s and their intensities A were calculated (CCSD at complete basis set limit). The validity of the previously proposed linear proportionality between the intensification of the stretching vibration ν_s in IR spectra and hydrogen bond enthalpy –ΔH = 12.2· (A.V.Iogansen, Spectrochimica Acta A 1999) was examined. It is shown that for a range of similar hydrogen bond types with complexation energies ∆E < 15 kcal/mol the ∆E() function remains similar to that proposed in the Iogansen’s work, while upon strengthening this dependency becomes significantly non-linear. We examined two other parameters ( and ) related to IR intensity as descriptors of hydrogen bond strength which are proportional to transition dipole moment matrix element and mass-independent dipole moment derivative. It was found that the dependency ∆E() stays linear in the whole studied range of complexation energies and it can be used for evaluation of ∆E from infrared spectral data with the accuracy about 2 kcal/mol. The mass-independent product is an appropriate descriptor for sets of complexes with various hydrogen bond types. Simple equations proposed in this work can be used for estimations of hydrogen bond strength in various systems, where experimental thermodynamic methods or direct calculations are difficult or even impossible.

A.S. Antonov, V.V. Karpov, E.Yu. Tupikina, P.M. Tolstoy, M.A. Vovk, “Aggregation Behavior of Lithionaphthalenes in Solution: Experimental and Theoretical Study”, Organometallics 2020, 39, 3705. DOI: 10.1021/acs.organomet.0c00524.

The aggregation of a series of mono- and dilithionaphthalenes in THF solutions in the presence of tetramethylethylenediamine (TMEDA) and pentamethyldiethylenetriamine (PMDTA) was studied by NMR spectroscopy and quantum chemical calculations. The stability of dimeric species in diluted solutions as well as reasons of their disaggregation in some cases has been discussed. For the lithioderivatives of 1,8-bis(dimethylamino)naphthalene (DMAN) the possibility of NMe₂ group coordination to the lithium atom in ortho-position of naphthalene core under steric pressure of substituents was demonstrated by quantum chemical calculations. For the first time, dilithionaphthalenes were studied by ¹H, ¹³C, and ⁷Li NMR spectroscopy. It was shown that while β-dilithionaphthalenes form oligomeric aggregates in solutions, α-dilithionaphthalenes exist as solely monomeric species with each lithium atom coordinated to both peri-positions.

E.Yu. Tupikina, K.G. Tokhadze, V.V. Karpov, G.S. Denisov, P.M. Tolstoy, “Stretching force constants as descriptors of energy and geometry of F···HF hydrogen bonds”, Spectrochim. Acta A 2020, 241, 118677. DOI: 10.1016/j.saa.2020.118677.

In this work applicability of proton donor group stretching vibration force constants k_s and intermolecular stretching force constants k_σ for evaluations of hydrogen bond strength and geometry are discussed. For a set of 30 complexes with F···HF hydrogen bonds in a wide range 0.5–48 kcal/mol by means of quantum chemical calculations equilibrium geometries, complexation energies, vibrational frequencies and corresponding force constants were calculated (MP2/aug-cc-pVTZ). It is shown, that properties of a hydrogen bond are more strictly correlated with the values of force constants than with vibrational frequencies. Easy-to-use equations for estimations of hydrogen bond energy ∆E and geometry (r_FH, r_FF) based on k_s and k_σ values are proposed.

A.S. Mazur, M.A. Vovk, P.M. Tolstoy, “Solid-state NMR of carbon nanostructures (graphite, graphene, carbon nanotubes, nanodiamonds, fullerene) in 2000-2019: a mini-review”, Fuller. Nanotub. Car. N. 2020, 28(3), 202-213. DOI: 10.1080/1536383X.2019.1686622.

A brief overview is given of the papers published over the last two decades on the subject of solid-state ¹³C NMR spectra of such carbon nanostructures as milled graphite and its oxide, graphene, graphene oxide, carbon nanotubes, nanodiamonds, fullerenes and their derivatives. The main focus is put on the characteristic values of experimental isotropic ¹³C NMR chemical shifts and their interpretation in terms of local chemical environments of carbon nuclei.

V.V. Mulloyarova, D.O. Ustimchuk, A. Filarowski, P.M. Tolstoy, “H/D Isotope Effects on ¹H NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids”, Molecules 2020, 25, 1907. DOI: 10.3390/molecules25081907

Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) ¹H-NMR and ³¹P-NMR using liquefied gases CDF₃/CDF₂Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.

A.S. Ostras’, D.M. Ivanov, A.S. Novikov, P.M. Tolstoy, “Phosphine oxides as spectroscopic halogen bond descriptors: IR and NMR correlations with interatomic distances and complexation energy”, Molecules 2020, 25, 1406. DOI: 10.3390/molecules25061406

An extensive series of 128 halogen-bonded complexes formed by trimethylphosphine oxide and various F-, Cl-, Br-, I- and At-containing molecules, ranging in energy from 0 to 124 kJ/mol, is studied by DFT calculations in vacuum. The results reveal correlations between R–X···O=PMe₃ halogen bond energy ∆E, X···O distance r, halogen’s σ-hole size, QTAIM parameters at halogen bond critical point and changes of spectroscopic parameters of phosphine oxide upon complexation, such as ³¹P NMR chemical shift, ∆δ_P, and P=O stretching frequency, ∆ν. Some of the correlations are halogen-specific, i.e., different for F, Cl, Br, I and At, such as ∆E(r), while others are general, i.e., fulfilled for the whole set of complexes at once, such as ∆E(∆δ_P). The proposed correlations could be used to estimate the halogen bond properties in disordered media (liquids, solutions, polymers, glasses) from the corresponding NMR and IR spectra.

E.Yu. Tupikina, G.S. Denisov, P.M. Tolstoy, “Lone Pairs Mapping by Laplacian of ³He NMR Chemical Shift”, J. Comput. Chem. 2020, 41, 1194-1199. DOI: 10.1002/jcc.26166.

Results of approbation of a new quantum mechanical approach of lone pairs visualization, its optimization and testing on a range of model molecules are presented. The main idea of proposed methodology is using ³He atom as a probe for investigating electronic shells of species with lone pairs. As model objects we consider “classical” examples of hydrogen cyanide, methanimine, ammonia, phosphine, formaldehyde, water and hydrogen sulfide. It is shown, that lone pairs can be visualized by means of 3D maps of Laplacian of ³He chemical shift Ѳδ_He. NMR calculations could be performed using level of theory as low as B3LYP/6-31G, allowing for the reduction of computational time without significant loss of quality. Advantages of our approach are discussed in comparison with usual methods of lone pairs visualization (ELF, MESP).

E. Yu. Tupikina, G. S. Denisov, A. S. Antonov, P. M. Tolstoy, “Unusual behaviour of the spin-spin coupling constant ¹J_CH upon formation of CH···X hydrogen bond”, Phys. Chem. Chem. Phys. 2020, 22, 1994-2000. DOI: 10.1039/C9CP05964D

One-bond coupling constants ¹J_XY are usually used as a measure of corresponding X…Y interatomic distances. However the physical nature of this correlation is not well understood and in some cases a conterintuitive behaviour of ¹J_XY upon hydrogen bonded complex formation has been reported. In this work the behavior of 1JCH upon formation and strengthening of complexes with CH···X hydrogen bonds and upon proton transfer process is investigated by means of ¹H NMR spectroscopy and quantum chemical calculations. ¹H NMR spectra of 1,1-dinitroethane solution at room temperature in various solvents (carbon tetrachloride, chloroform, dichloromethane, acetone, dimethylformamide and dimethyl sulfoxide) illustrate the increase of ¹J_CH by several Hz upon increase of the complex strength. Computational results (MP2/aug-cc-pVDZ) reproduce this observation and allow one to conclude that the increase of ¹J_CH is mainly caused by the change of the carbon hybridization (an increase of s-character), rather than by the change in interatomic distance r_CH. The behavior of ¹J_CH was also examined computationally in a wide range of CH···X hydrogen bonds’ energies and geometries. For this purpose quantum-chemical modeling of the partial proton transfer process for complexes formed by 1,1-dinitroethane and trinitromethane as hydrogen bond donors with acetone, pyridine and fluoride anion as hydrogen bond acceptors was performed. Obtained results have confirmed the abovementioned idea – for rather weak complexes the dominant impact on the change of ¹J_CH magnitude is the increase of the s-character of carbon atom hybridization, while for complexes with a significantly transferred proton the exponential decrease of the Fermi-contact term dominates.

A.A. Antonov, A.A. Yakubenko, “Noncovalent Li···H Interaction in the Synthesis of peri-Disubstituted Naphthalene Proton Sponges”, Synthesis 2020; 52, 98-104. DOI: 10.1055/s-0039-1690230

Noncovalent Li···H interaction was utilised as a tool for the second lithiation of 4-lithio-1,8-bis(dimethylamino)naphthalene with n-BuLi in the presence of TMEDA in hexane. Metallation proceeds with 100% selectivity in the second peri-position and with up to 90% yield. A series of 4,5-disubstituted derivatives of 1,8-bis(dimethylamino)naphthalene has been prepared in good to excellent yield after quenching the reaction mass with different electrophiles.

V. Mikshiev, A.F. Pozharskii, A. Filarowski, A.S. Novikov, A.S. Antonov, P.M. Tolstoy. M.A. Vovk, O.V. Khoroshilova, “How strong is hydrogen bonding to amide nitrogen?”, Chem. Phys. Chem. 2020, 21, 651-658. DOI: 10.1002/cphc.201901104.

The protonation of the carboxamide nitrogen atom is an essential part of in vivo and in vitro processes (cis‐trans isomerization, amides hydrolysis etc). This phenomenon is well studied in geometrically strongly distorted amides, although there is little data concerning the protonation of undistorted amides. In the latter case, the participation of amide nitrogen in hydrogen bonding (which can be regarded as the incipient state of a proton transfer process) is less well‐studied. Thus, it would be a worthy goal to investigate the enthalpy of this interaction. We prepared and investigated a set of peri‐substituted naphthalenes containing the protonated dimethylamino group next to the amide nitrogen atom (“amide proton sponges”), which could serve as models for the study of an intramolecular hydrogen bond with the amide nitrogen atom. X‐Ray analysis, NMR spectra, basicity values as well as quantum chemical calculations revealed the existence of a hydrogen bond with the amide nitrogen, that should be attributed to the borderline between moderate and weak intramolecular hydrogen bonds (2–7 kcal·mol‒1).

A.S. Antonov, V.G. Bardakov, V.V. Mulloyarova, “Sterically facilitated meta-lithiation of arenes, containing electron-donating groups”, J. Org. Chem. 2020, 906, 121068. DOI: 10.1016/j.jorganchem.2019.121068

The influence of the bulky trimethylsilyl substituent on the selectivity of metallation of dimethylaniline, anisole and 1-dimethylaminonaphthalene is studied. The neighboring SiMe3 group forces dimethylamino and methoxy groups to occupy a conformation with an unshared electron pair turned towards silicon atom. This forced conformation prevents NMe2 and OMe groups from providing the DOM-effect, thus facilitating meta-metallation with the use of bulky LiCKOR. While the inverted NMe2 group completely suppresses ortho-metallation, the less bulky and more electron withdrawing OMe group demonstrates more rotation freedom allowing selective ortho-metallation with smaller reagents such as n-BuLi or tert-BuLi.

V.V. Mulloyarova, I.S. Giba, G.S. Denisov, A.S. Ostras’, P.M. Tolstoy, “Conformational Mobility and Proton Transfer in Hydrogen-Bonded Dimers and Trimers of Phosphinic and Phosphoric Acids”, J. Phys. Chem. A. 2019, 123, 6761−6771. DOI: 10.1021/acs.jpca.9b05184.

The monomers, H-bonded cyclic dimers, and trimers of five acids were studied by density functional theory calculations, such as hypophosphorous acid (H₂POOH, 1), dimethylphosphinic acid (Me₂POOH, 2), phenylphosphinic acid (PhHPOOH, 3), dimethylphosphoric acid ((MeO)₂POOH, 4), and diphenylphosphoric acid ((PhO)₂POOH, 5). Particular attention was paid to the conformational manifold existing due to the internal degrees of freedom: proton transfer (PT), puckering (“twist”) within the ring of H-bonds, and mobility of the substituents
(namely, −Ph, −OMe, and −OPh rotations). The energy barriers for the transitions between conformers are rather low (<6 kcal/mol for PTs, <2.5 kcal/mol for puckerings, and ca. <3 kcal/mol for rotations of substituents), such that the fast exchange regime in the NMR timescale and subsequent δP averaging are expected. Correlations are proposed linking the change of average δP with the H-bond energy, showing the slope of ca. 4 ppm per kcal/mol. The sensitivity of δP to the OPO angle and the OPOH dihedral angle and the geometries of both H-bonds formed by the POOH moiety are analyzed.

E.Yu. Tupikina, M.Sigalov, I.G. Shenderovich, V.V. Mulloyarova, G.S. Denisov, P.M. Tolstoy, “Correlations of NHN hydrogen bond energy with geometry and 1H NMR chemical shift difference of NH protons for aniline complexes”, J. Chem. Phys. 2019, 150, 114305/1–10. DOI 10.1063/1.5090180.

In this computational work we propose to use the NMR chemical shift difference of NH₂ protons for 1:1 complexes formed by aniline and nitrogen-containing proton acceptors for the estimation of the hydrogen bond energy and geometry (N…H and N…N distances). The proposed correlations could be applied to other aromatic amines as well, in a gas phase, a solution or a solid state, both for inter- and intramolecular hydrogen bonds. We considered a set of 21 complexes with NHN hydrogen bond without proton transfer, including hydrogen bonds from weak to medium strong ones (2–21 kcal/mol), with neutral or anionic bases, with sp³ and sp² hybridized nitrogen proton acceptor. For each complex apart of direct hydrogen bond energy calculation we have tested several other ways to estimate the energy: a) using a correlation between NH stretching band intensity and hydrogen bond energy and b) using correlations between electron density properties at (3, –1) bond critical point (QTAIM analysis) and hydrogen bond energy. Besides for the studied type of complexes we obtained refined linear correlations linking the local electron kinetic (G) and potential (V) energies densities with the hydrogen bond energy.

E.Yu. Tupikina, G.S. Denisov, P.M. Tolstoy, “Anticooperativity of FH···Cl^– hydrogen bonds in [(FH)_nCl]^– clusters (n = 1…6)”, J. Comput. Chem. 2019, 40, 2858-2867. DOI: 10.1002/jcc.26066.

The change of cooperativity of FH···Cl^– hydrogen bonds upon sequential addition of up to six FH molecules to the Cl^– first coordination sphere is investigated. The geometry of clusters [(FH)_nCl]^– (n = 1…6) was calculated (CCSD/aug-cc-pVDZ) and compared with [(FH)_nF]^– clusters. The geometry is determined by the symmetry-driven electrostatic requirements and also by the fact that formation of each new FH···Cl^– bond creates a depression in the chlorine’s electron cloud on the opposite side of Cl^– (s-hole), which limits the range of directions available for subsequent H-bond formation. The mutual influence of FH···Cl^– hydrogen bonds is anticooperative – the addition of each FH molecule weakens H-bonds by 23–16% and decreases their covalent character (as seen by LMO-EDA decomposition and QTAIM analysis). Anticooperativity effects could be tracked by spectroscopic parameters (frequency of local HF mode ν_FH, chemical shift δ_H, spin-spin coupling constants ¹J_FH, ^1hJ_HCl, ^2hJ_FCl and nuclear quadrupolar constants χ_18F, χ_2H and χ_35Cl.

A. F. Pozharskii, V. A. Ozeryanskii, V. Y. Mikshiev, A. V. Chernyshev, A. V. Metelitsa, A. S. Antonov, “Proton-induced fluorescence in modified quino[7,8-h]quinolines: dual sensing for protons and π-donors”, Org. Biomol. Chem., 2019, 17, 8221-8233. DOI: 10.1039/C9OB01391A.

The synthesis, as well as spectral, structural and photoluminescence properties of dipyrido[3,2-e:2′,3′-h]acenaphthene 5 and quinazolino[7,8-h]quinazolines 6 as representatives of the bidentate –N/–N superbases, are reported. These nitrogen bases being more rigid (5) or π-extended (6) analogs of optically-mute quino[7,8-h]quinoline are both active in terms of fluorescence with quantum yields up to ϕ = 0.71–0.77. At the same time, their luminescence behavior is opposite to that of peri-NMe2/NMe2 naphthalene proton sponges and their hybrid NMe2/–N analogs. Although 5 and 6 exhibit visible region emission upon protonation, for the hybrid systems the fluorescence is manifested only for bases. The most remarkable observation is that the fluorescence of compound 5 can be switched on not only by means of organic or inorganic acids, but also through the formation of chelate complexes with such weak H-donors as water and primary alcohols. It was disclosed that water is present in the complex as a cluster comprising 8 interconnected H₂O molecules. Overall, the studied compounds demonstrate a previously unobserved type of dual mode optical response, H-sensing (emission enhancement in 5 and 6 on protonation) and π-sensing (emission quenching in 5H+ and 6H+ on coordination with π-donors). This work seems to be an important contribution to areas such as chemosensorics, the creation of new ligands, hydrogen transfer and some other phenomena representing different types of supramolecular interactions.

I.S. Giba, V.V. Mulloyarova, G.S. Denisov, P.M. Tolstoy, “Influence of Hydrogen Bonds in 1:1 Complexes of Phosphinic Acids with Substituted Pyridines on ¹H and ³¹P NMR Chemical Shifts”, J. Phys. Chem. A., 2019, 123, 2252-2260. DOI: 10.1021/acs.jpca.9b00625.

Two series of 1:1 complexes with strong OHN hydrogen bonds formed by dimethylphosphinic and phenylphosphinic acids with 10 substituted pyridines were studied experimentally by liquid state NMR spectroscopy at 100 K in solution in a low-freezing polar aprotic solvent mixture CDF₃/CDClF₂. The hydrogen bond geometries were estimated using previously established correlations linking ¹H NMR chemical shifts of bridging protons with the O...H and H...N interatomic distances. A new correlation is proposed allowing one to estimate the interatomic distance within the OHN bridge from the displacement of ³¹P NMR signal upon complexation. We show that the values of ³¹P NMR chemical shifts are affected by an additional CH···O hydrogen bond formed between the P=O group of the acid and ortho-CH proton of the substituted pyridines. Breaking of this bond in case of 2,6-disubstituted bases shifts the ³¹P NMR signal by ca. 1.5 ppm to the high field.

2021

1. E.Yu. Tupikina, P.M. Tolstoy, A.A. Titova, M.A. Kostin, G.S. Denisov, “Estimations of FH···X hydrogen bond energies from IR intensities: Iogansen's rule revisited”, J. Comput. Chem. 2021, 41. DOI: 10.1002/jcc.26482
2. I.S. Giba, V.V. Mulloyarova, G.S. Denisov, P.M. Tolstoy, “Sensitivity of ³¹P NMR chemical shifts to hydrogen bond geometry and molecular conformation for complexes of phosphinic acids with pyridines”, Magn. Reson. Chem. 2020, accepted. DOI: 10.1002/mrc.5123.
3. V. Rozentsvet, N. Sablina, D. Ulyanova, S. Kostjuk, P. Tolstoy, “Structure of terminal units of polybutadiene synthesized via anionic mechanism”, Polym. Bull. 2021, accepted

2020

1. K. Sotiriadis, P. Mácová, A.S. Mazur, A. Viani, P.M. Tolstoy, S. Tsivilis, “Long-term thaumasite sulfate attack on Portland-limestone cement concrete: A multi-technique analytical approach for assessing phase assemblage”, Cement and Concrete Research 2020, 130, 105995. DOI: 10.1016/j.cemconres.2020.105995.
2. N.M. Kuznetsov, S.I. Belousov, A.V. Bakirov, S.N. Chvalun, R.A. Kamyshinsky, A.A. Mikhutkin, A.L. Vasiliev, P.M. Tolstoy, A.S. Mazur, E.D. Eidelman, E.B. Yudina, A.Ya. Vul', “Unique rheological behavior of detonation nanodiamond hydrosols: the nature of sol-gel transition”, Carbon 2020, 161, 486-494. DOI: 10.1016/j.carbon.2020.01.054.
3. A.Yu. Baranov, A.S. Berezin, D.G. Samsonenko, A.S. Mazur, P.M. Tolstoy, V.F. Plyusnin, I.E. Kolesnikov, A.V. Artem'ev, “New Cu(I) halide complexes showing TADF combined with room temperature phosphorescence: the balance tuned by halogens”, Dalton Trans. 2020, 49, 3155-3163. DOI: 10.1039/D0DT00192A.
4. I. Kritskiy, T. Volkova, S. Ivanov, A. Mazur, P. Tolstoy, I. Terekhova, “Methotrexate-Loaded Metal-Organic Frameworks on the Basis of γ-Cyclodextrin: Design, Characterization, in Vitro and in Vivo Investigation”, Materials Science and Engineering C 2020, 111, 10774. DOI: 10.1016/j.msec.2020.110774.
5. V.А. Rozentsvet, N.А. Sablina, D.M. Ulyanova, P.M. Tolstoy, S.N. Smirnov, I.A. Novakov, “Identification of the structure of polybutadiene terminal units by NMR spectroscopy with T2-filter”, Doklady Phys. Chem. 2020, 491, 40-42. DOI: 10.1134/S0012501620040028.
6. V. Rozentsvet, N. Sablina, D. Ulyanova, M. Kuznetsova, S. Kostjuk, P. Tolstoy, “A new approach towards investigation of structure of terminal units of poly(1,3-pentadiene) using T2-filtered NMR spectroscopy”, Macromol. Chem. Phys. 2020, 2000168. DOI: 10.1002/macp.202000168.
7. A.S. Antonov, V.V. Karpov, E.Yu. Tupikina, P.M. Tolstoy, M.A. Vovk, “Aggregation Behavior of Lithionaphthalenes in Solution: Experimental and Theoretical Study”, Organometallics 2020, 39, 3705. DOI: 10.1021/acs.organomet.0c00524.
8. A.S. Antonov, E.Yu. Tupikina, V.V. Karpov, V.V. Mulloyarova, V.G. Bardakov, “Sterically Facilitated Intramolecular Nucleophilic NMe2 Group Substitution in the Synthesis of Fused Isoxazoles: Theoretical Study”, Molecules, 2020, 25, 5977. DOI: 10.3390/molecules25245977.
9. A.S. Antonov, V.G. Bardakov, V.V. Mulloyarova, “Sterically facilitated meta-lithiation of arenes, containing electron-donating groups”, J. Org. Chem. 2020, 906, 121068. DOI: 10.1016/j.jorganchem.2019.121068
10. A.A. Antonov, A.A. Yakubenko, “Noncovalent Li···H Interaction in the Synthesis of peri-Disubstituted Naphthalene Proton Sponges”, Synthesis 2020; 52, 98-104. DOI: 10.1055/s-0039-1690230
11. E. Yu. Tupikina, G. S. Denisov, A. S. Antonov, P. M. Tolstoy, “Unusual behaviour of the spin-spin coupling constant 1JCH upon formation of CH•••X hydrogen bond”, Phys. Chem. Chem. Phys. 2020, 22, 1994-2000. DOI: 10.1039/C9CP05964D
12. E. Yu. Tupikina, K. G. Tokhadze, G. S. Denisov, P. M. Tolstoy, “Lone pairs mapping by Laplacian of ³He NMR chemical shift”, J. Comput. Chem. 2020, 41, 1194-1199. DOI: 10.1002/jcc.26166.
13. E.Yu. Tupikina, K.G. Tokhadze, V.V. Karpov, G.S. Denisov, P.M. Tolstoy, “Stretching force constants as descriptors of energy and geometry of F···HF hydrogen bonds”, Spectrochim. Acta A 2020, 241, 118677. DOI: 10.1016/j.saa.2020.118677.
14. A.S. Mazur, M.A. Vovk, P.M. Tolstoy, “Solid-state NMR of carbon nanostructures (graphite, graphene, carbon nanotubes, nanodiamonds, fullerene) in 2000-2019: a mini-review”, Fuller. Nanotub. Car. N. 2020, 28(3), 202-213. DOI: 10.1080/1536383X.2019.1686622.
15. A.S. Ostras’, D.M. Ivanov, A.S. Novikov, P.M. Tolstoy, “Phosphine oxides as spectroscopic halogen bond descriptors: IR and NMR correlations with interatomic distances and complexation energy”, Molecules 2020, 25, 1406. DOI: 10.3390/molecules25061406.
16. V.Y. Mikshiev, A.F. Pozharskii, A. Filarowski, A.S. Novikov, A.S. Antonov, P.M. Tolstoy, M.A. Vovk, O.V. Khoroshilova, “ How strong hydrogen bond with amide nitrogen atom is?”, ChemPhysChem, 2020, 21, 651-658. DOI: 10.1002/cphc.201901104.
17. V.V. Mulloyarova, D.O. Ustimchuk, A. Filarowski, P.M. Tolstoy, «H/D Isotope Effects on ¹H NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids», Molecules 2020, 25, 1907. DOI: 10.3390/molecules25081907.
18. K. Jóźwiak, A. Jezierska, J.J. Panek, E.A. Goremychkin, P.M. Tolstoy, I.G. Shenderovich, A. Filarowski, “Inter- vs. intra-molecular hydrogen bond patterns and proton dynamics in phthalic acid associates”, Molecules 2020, 25, 4720. DOI: 10.3390/molecules25204720.
19. V. Torres-Barthelemy, N. Pérez-Hernández, I.G. Shenderovich, P.M. Tolstoy, G.S. Denisov, H.-H. Limbach, “NMR-detected Host-Guest Proton Exchange as a novel Tool to study Surface/Volume Ratios and Filling of Cavities of mesoporous Solids”, J. Phys. Chem. C 2020, 124(40), 22082-22095. DOI: 10.1021/acs.jpcc.0c04889.
20. P. Piękoś, A. Jezierska, J. Panek, E.A. Goremychkin, A. Pozharskii, A. Antonov, P. Tolstoy, A. Filarowski, “Symmetry/asymmetry of NHN hydrogen bond in protonated 1,8-bis(dimethylamino)naphthalene”, Symmetry 2020, 12, 1924. DOI: 10.3390/sym12111924.
21. S.N. Yunusova, D.S. Bolotin, M.A. Vovk, P.M. Tolstoy, V.Yu. Kukushkin, “Tetrabromomethane as an Organic Catalyst: a Kinetic Study of CBr₄-Catalyzed Schiff Condensation”, Eur. J. Org. Chem. 2020, 6763-6769. DOI: 10.1002/ejoc.202001180.
22. D.L. Melnikova, Z.F. Badrieva, M.A. Kostin, C. Maller, M. Stas, A. Buczek, M.A. Broda, T. Kupka, A.-M. Kelterer, P.M. Tolstoy, V.D. Skirda, “On Complex Formation Between 5-Fluorouracil and beta-Cyclodextrin in Solution and in the Solid State: IR Markers and Detection of Short-Lived Complexes by Diffusion NMR”, Molecules 2020, 25, 5706. DOI: 10.3390/molecules25235706.

2019

1. V.A. Rozentsvet, V.G. Kozlov, O.A. Stotskaya, S.N. Smirnov, P. M. Tolstoy, “New approach to the study of the structure of polyisoprene obtained by cationic polymerization”, Russ. Chem. Bul., 2019, 68(1), 116-120. DOI: 10.1007/s11172-019-2425-3.
2. M. Shevtsov, S. Stangl, B. Nikolaev, L. Yakovleva, Y. Marchenko, R. Tagaeva, W. Sievert, E. Pitkin, A. Mazur, P. Tolstoy, O. Galibin, V. Ryzhov, K. Steiger, W. Khachatryan, K.A. Chester, G. Multhoff, “Granzyme B functionalized nanoparticles targeting membrane Hsp70-positive tumors for multimodal cancer theranostics”, Small, 2019, 15, 1900205. DOI: 10.1002/smll.201900205.
3. V.E. Eremyashev, A.S. Mazur, P.M. Tolstoi, L.M. Osipova, “Structure of Rubidium Borosilicate Glasses Studied by Nuclear Magnetic Resonance Spectroscopy”, Inorganic Materials, 2019, 55, 500-505. DOI: 10.1134/S0020168519050054.
4. N.N. Sheveleva, D.A. Markelov, M.A. Vovk, M.E. Mikhailova, I.I. Tarasenko, P.M. Tolstoy, I.M. Neelov, E. Lähderanta, “Poly-L-lysine dendrimer with side arginine segments”, RSC Adv., 2019, 9, 18018. DOI: 10.1039/c9ra02461a.
5. D. Lenz, B. Koeppe, P.M. Tolstoy, H.-H. Limbach, “An Efficient Perkin Synthesis of 13C-Labelled Cinnamic Acids From Acetic Acid as the Source of the Rare Isotope”, J. Label. Compd. Radiopharm., 2019, 62, 298-300. DOI: 10.1002/jlcr.3753.
6. I.S. Giba, V.V. Mulloyarova, G.S. Denisov, P.M. Tolstoy, “Influence of Hydrogen Bonds in 1:1 Complexes of Phosphinic Acids with Substituted Pyridines on ¹H and ³¹P NMR Chemical Shifts”, J. Phys. Chem. A 2019, 123, 2252-2260. DOI: 10.1021/acs.jpca.9b00625.
7. E.Yu. Tupikina, M. Sigalov, I.G. Shenderovich, V.V. Mulloyarova, G.S. Denisov, P.M. Tolstoy, “Correlations of NHN hydrogen bond energy with geometry and ¹H NMR chemical shift difference of NH protons for aniline complexes”, J. Chem. Phys. 2019, 150, 114305. DOI: 10.1063/1.5090180.
8. V.V. Mulloyarova, I.S. Giba, G.S. Denisov, P.M. Tolstoy, “Conformational mobility and proton transfer in hydrogen-bonded dimers and trimers of phosphinic and phosphoric acids”, J. Phys. Chem A 2019, 123, 6761-6771. DOI: 10.1021/acs.jpca.9b05184.
9. E.Yu. Tupikina, G.S. Denisov, P.M. Tolstoy, “Anticooperativity of FH···Cl^– hydrogen bonds in [(FH)_nCl]^– clusters (n = 1…6)”, J. Comput. Chem. 2019, 40, 2858-2867. DOI: 10.1002/jcc.26066.
10. A. Jezierska, P. Tolstoy, J. Panek, A. Filarowski, “Intramolecular hydrogen bonds in selected aromatic compounds: recent developments”, Catalysts 2019, 9, 909. DOI: 10.3390/catal9110909.
11. M.L. Khkhlov, A.E. Miroslavov, E.K. Legin, N.A. Korsakova, A.I. Kostylev, V.V. Gurzhiy, A.Yu. Ivanov, P.M. Tolstoi, “Tris(methyltrihydroborato)(tetrahydrofuran) ytterbium(iii) complex: structure and volatility”, Mendeleev Comm., 2019, 29, 696-697. DOI: 10.1016/j.mencom.2019.11.032.

Information for students

We invite bachelor students and 1^st year master students to perform investigations for their qualification works in our laboratory in the following areas:

• NMR spectroscopy (Prof. Dr. Peter M. Tolstoy, room 2150, This email address is being protected from spambots. You need JavaScript enabled to view it.)
• Organometallic chemistry (Prof. Dr. Alexander S. Antonov, room 2123, This email address is being protected from spambots. You need JavaScript enabled to view it.)
• Quantum chemistry (Dr. Elena Yu. Tupikina, room 2123, This email address is being protected from spambots. You need JavaScript enabled to view it.)