Article
Chemistry, Physical
Juan J. J. Aucar, Alejandro F. F. Maldonado, Juan I. I. Melo
Summary: In this work, relativistic corrections to the electric field gradient (EFG) are presented, including spin-dependent corrections for the first time. The results show that these new corrections significantly improve the performance of the existing method and are in close agreement with calculations at the four-component Dirac-Hartree-Fock (4c-DHF) level. The accuracy of the EFG values obtained with this new method allows for the analysis of the electronic origin of relativistic effects using well-known nonrelativistic operators.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Multidisciplinary
Ibon Alkorta, Rosa M. Claramunt, Dionisia Sanz, Jose Elguero, Wolfgang Holzer
Summary: This work reports the C-13 and N-15 chemical shifts of various iodopyrazoles, including both non-relativistic and relativistic calculations, and also investigates issues related to NH-pyrazoles. The manuscript aims to develop equations containing corrections for heavy atoms to predict C-13 and N-15 chemical shifts.
STRUCTURAL CHEMISTRY
(2021)
Article
Chemistry, Physical
Stefan Knecht, Michal Repisky, Hans Jorgen Aagaard Jensen, Trond Saue
Summary: The study introduces two methods to correct picture-change effects in exact two-component Hamiltonian framework, demonstrating high accuracy and computational efficiency in calculating molecular energies and properties, verified through experiments on two classes of molecules.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Nanoscience & Nanotechnology
Hamadou Hadidjatou, Olivier Holtomo, Ousmanou Motapon
Summary: This study investigates the effects of solvents on the structures and nuclear magnetic resonance spectroscopy of three pro-lithospermate molecules. The solvent effects on the geometrical parameters are found to be weak, and better results are obtained by using the B3LYP-D3BJ/6-31++G(d,p) method in DMSO for the calculation of chemical shifts.
Article
Biochemistry & Molecular Biology
Irina L. Rusakova, Yuriy Yu. Rusakov
Summary: The sensitivity of relativistic corrections to NMR shielding constants to the configuration of angular spaces of the basis sets was investigated using four-component density functional theory. The dependence of relativistic corrections to s of light nuclei on the basis set used on the light spectator atom was found to be similar to the Fermi-contact contribution to the nonrelativistic spin-spin coupling constant. The artificially saturated nonrelativistic J-oriented and s-oriented basis sets provided better accuracy than standard nonrelativistic s-oriented basis sets for calculating relativistic corrections to NMR shielding constants.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Physical
Yuriy Yu. Rusakov, Irina L. L. Rusakova
Summary: The basis sets used in quantum chemical calculations of P-31 NMR chemical shifts have a significant impact on their accuracy. Existing basis sets for phosphorus atom lack flexibility in important angular regions, leading to misassignments in P-31 NMR spectra. This study proposes new pecS-n (n = 1, 2) basis sets that demonstrate high accuracy and are useful in large-scale quantum chemical calculations of P-31 NMR chemical shifts.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Mariano T. Colombo Jofre, Karol Koziol, I Agustin Aucar, Konstantin Gaul, Robert Berger, Gustavo A. Aucar
Summary: This article investigates the physics behind the indirect spin-spin coupling tensor J in systems containing mercury nuclei. By performing calculations, it is found that the paramagnetic-like mechanism contributes over 99.98% to the total coupling tensor value. The s-type valence atomic orbitals play a dominant role in describing the coupling. Through estimation, it is discovered that quantum electrodynamics effects result in corrections ranging from 0.7% to 1.7% of the total coupling constant.
JOURNAL OF CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Renan V. Viesser, Claudio F. Tormena
Summary: The study reveals an inverse halogen dependence (IHD) in the anion series due to negative spin-orbit contribution rather than scalar paramagnetic effects. The presence of a carbon nonbonding orbital in anions allows for magnetic couplings that generate a deshielding effect on the nucleus, contradicting the classical association between delta C-13 and atomic charge.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2021)
Article
Chemistry, Inorganic & Nuclear
Iben Glent-Madsen, Anders Reinholdt, Jesper Bendix, Stephan P. A. Sauer
Summary: Carbide-bridged ruthenium platinum complexes show a linear correlation between carbide chemical shifts and platinum-carbide coupling constants, which is investigated computationally. Relativistic effects play a significant role in these complexes, affecting sigmaC and Pt-C coupling constants. The linear correlation is attributed to changes in spin-orbit coupling and trans-influence of the ligand L.
Review
Chemistry, Inorganic & Nuclear
Irina L. L. Rusakova, Yuriy Yu. Rusakov
Summary: This review summarizes computational studies on the relativistic effects on NMR chemical shifts of light nuclei in molecules containing heavy main group p-block elements. The article discusses relativistic theories and quantum chemical methods for calculating relativistic NMR chemical shifts. The main focus is on the relativistic calculations of NMR shielding constants of popular light nuclei in compounds with heavy p-elements, particularly the effects of 16th and 17th group elements. The article also considers factors influencing the behavior of relativistic effects on the chemical shifts of light atoms, including the stereochemistry of the relativistic heavy atom and the influence of spin-orbit relativistic effects on the vibrational contributions to the shielding constants of light nuclei.
Article
Physics, Nuclear
Jingyi Zhou, Vladimir Khachatryan, Igor Akushevich, Haiyan Gao, Alexander Ilyichev, Chao Peng, Stanislav Srednyak, Weizhi Xiong
Summary: This paper presents the numerical calculations of the lowest-order radiative corrections in electron-deuteron scattering for the DRad experiment and estimates the systematic uncertainty on rd arising from higher-order radiative corrections.
EUROPEAN PHYSICAL JOURNAL A
(2023)
Article
Chemistry, Inorganic & Nuclear
Dmitry O. O. Samultsev, Valentin A. A. Semenov, Leonid B. B. Krivdin
Summary: The relativistic effects on the shielding constants of various nuclei and their importance in theoretical calculations of chelate complexes were studied. The accuracy factors affecting the calculation of chemical shifts were analyzed. It was found that relativistic effects have a significant impact on the results.
Article
Chemistry, Multidisciplinary
Valentin A. Semenov, Leonid B. Krivdin
Summary: Based on the calculations of NMR chemical shifts, several spectral reassignments and corrections were made to the H-1 and C-13 NMR spectra of the large trimeric indole alkaloid strychnohexamine. New assignments of diastereotopic protons were made and the chemical shifts of unassigned carbon and protons were predicted.
MAGNETIC RESONANCE IN CHEMISTRY
(2021)
Review
Chemistry, Inorganic & Nuclear
Lyudmila I. Larina
Summary: This review discusses the stereochemical structure of functionalized azoles and related compounds obtained by NMR spectroscopy and quantum chemistry, highlighting the importance of understanding their chemical behavior and biological activity.
Article
Chemistry, Multidisciplinary
Ekaterina A. Verochkina, Nadezhda V. Vchislo, Lyudmila Larina, Evgenii A. Titov
Summary: Previously unknown derivatives of thiosemicarbazide were successfully synthesized by condensation reaction, and their corresponding complexes with copper (II) chloride were also obtained. The compounds showed good solubility and significant biological activity. The preliminary screening for acute toxicity indicated that the studied compounds have a low risk of toxicity.
IZVESTIYA VUZOV-PRIKLADNAYA KHIMIYA I BIOTEKHNOLOGIYA
(2022)
Article
Chemistry, Multidisciplinary
Elena Chirkina, Lyudmila Larina
Summary: Derivatives of 1,2,4-triazole exhibit various activities, and understanding the reaction mechanism can help control the chemical synthesis process. Quantum chemical simulation can reveal information about the elementary stages of the reaction, intermediate compounds, and transition states.
STRUCTURAL CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Lyudmila I. Larina, Alexander I. Albanov, Stanislav N. Zelinskiy, Vadim V. Annenkov, Irina L. Rusakova
Summary: Substituted acrylamides are widely used in organic and medical chemistry, and understanding their electronic structure, spectral properties, and stereochemical transformations is crucial. The structure and stereodynamic behavior of these compounds were studied using dynamic and multinuclear NMR spectroscopy. The results show that acrylamides exist in solution as Z- and E-isomers, with the E-isomer being more prevalent. The experimental values obtained for the activation energy of the isomers range from 15-17 kcal/mol, depending on the stereochemical structure.
MAGNETIC RESONANCE IN CHEMISTRY
(2023)
Article
Biochemistry & Molecular Biology
Valentin A. Semenov, Leonid B. Krivdin
Summary: Succeeding variants of SARS-CoV-2 have increased contagion. Inhibiting the binding of spike protein to the ACE2 receptor is a potential strategy to prevent COVID-19 infection. By using pharmacophore models and induced fit docking, natural compounds that could serve as inhibitors were identified. These findings will stimulate further research and drug development.
Review
Biochemistry & Molecular Biology
Lyudmila Larina
Summary: This review provides extensive data on the stereochemical structure of functionalized organophosphorus azoles and related compounds using multinuclear NMR spectroscopy and quantum chemistry. The most convenient and reliable approach to studying the phosphorus atoms and evaluating the Z/E isomerization is through P-31 NMR spectroscopy combined with high-level quantum-chemical calculations.
Article
Biochemistry & Molecular Biology
Valentin A. Semenov, Leonid B. Krivdin
Summary: H-1 and C-13 NMR chemical shifts of alasmontamine A, a tetracyclic monoterpene indole alkaloid with a molecular formula of C84H91N8O12, were calculated using DFT framework. Six lowest energy conformers and three key configurations contributing to NMR shielding constants were identified. Ambiguities in the reported assignment of NMR chemical shifts of alasmontamine A were resolved.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Organic
V. G. Fedoseeva, E. A. Verochkina, L. I. Larina, N. V. Vchislo
Summary: The condensation of 2-alkylsulfanyl-substituted 2-en-4-ynals with N,N- and N,O-binucleophiles results in the formation of the corresponding 1,3-perhydrodiazines, 1,3-imidazolidines, and 1,3-oxazolidines, maintaining the original combination of substituents.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Inorganic & Nuclear
Dmitry O. O. Samultsev, Valentin A. A. Semenov, Leonid B. B. Krivdin
Summary: The relativistic effects on the shielding constants of various nuclei and their importance in theoretical calculations of chelate complexes were studied. The accuracy factors affecting the calculation of chemical shifts were analyzed. It was found that relativistic effects have a significant impact on the results.
Review
Biochemistry & Molecular Biology
Lyudmila Larina
Summary: The review provides extensive data on the structure of C- and N-chlorophosphorylated enamines and related heterocycles obtained by multipulse multinuclear NMR spectroscopy. The use of phosphorus pentachloride enables the synthesis of various C- and N-phosphorylated products, forming promising nitrogen- and phosphorus-containing heterocyclic systems. P-31 NMR spectroscopy is a convenient and reliable method for studying organophosphorus compounds and determining their coordination numbers and isomeric forms. Alteration of the coordination number of the phosphorus atom in the phosphorylated compounds leads to a significant shift in the P-31 resonance.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Article
Chemistry, Physical
Mikhail V. Andreev, Vladimir A. Potapov, Maxim V. Musalov, Lyudmila I. Larina
Summary: An efficient method for synthesizing a novel family of (Z)-3-amino-3-oxo-1-propenyl selenocyanates was developed using KSeCN and 3-trimethylsilyl-2-propynamides in the presence of ammonium chloride. The reaction involved desilylation and exhibited regio- and stereoselective anti-addition to yield vinyl selenocyanates with a (Z)-configuration in high yields. The absence of ammonium chloride prevented the formation of the desired products.
Article
Chemistry, Physical
Mikhail V. Andreev, Vladimir A. Potapov, Maxim V. Musalov, Lyudmila I. Larina
Summary: The first examples of reactions of 3-trimethylsilyl-2-propynamides with organic diselenides were reported, leading to the synthesis of 3-alkylselanyl-2-propenamides and 3-organylselanyl-2-propynamides. The reactions showed good regio- and stereoselectivity with high yields. Additionally, unsymmetrical divinyl selenides with cyclic amide groups and a product containing multiple selanyl-2-propenamide moieties were synthesized.
Article
Chemistry, Inorganic & Nuclear
Vladimir A. Potapov, Mikhail V. Andreev, Maxim V. Musalov, Irina V. Sterkhova, Svetlana V. Amosova, Lyudmila I. Larina
Summary: The efficient syntheses of novel compounds, (Z,Z)-bis(3-amino-3-oxo-1-propenyl) selenides and diselenides, were achieved via nucleophilic addition reactions. The obtained diselenides showed superior glutathione peroxidase-like activity compared to selenides with the same substituents. Structural analysis through X-ray diffraction and Se-77-NMR data confirmed the structures of the products.
Article
Chemistry, Organic
Kseniya O. Khrapova, Anton A. Telezhkin, Pavel A. Volkov, Lyudmila I. Larina, Dmitry V. Pavlov, Nina K. Gusarova, Boris A. Trofimov
Summary: The reaction between secondary phosphine chalcogenides and primary amino alcohols can selectively deliver amides of chalcogenophosphinic acids under mild conditions, while in a similar reaction, mono-cross-coupling with aminophenols only occurs with the participation of phenolic hydroxyl to give aminophenylchalcogenophosphinic O-esters. The yields of the synthesized functional amides or esters are between 60-85%.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2021)
