1
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Ai S, Huang Z, Yu W, Huang C. Efficient dissolution of cellulose in slow-cooling alkaline systems and interacting modes between alkali and urea at the molecular level. Carbohydr Res 2024; 536:109054. [PMID: 38350405 DOI: 10.1016/j.carres.2024.109054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Revised: 02/02/2024] [Accepted: 02/08/2024] [Indexed: 02/15/2024]
Abstract
The dissolution of microcrystalline cellulose (MCC) in a urea-NaOH system is beneficial for its mechanical processing. The apparent MCC solubility was greatly improved to 14 wt% under a slow-cooling condition with a cooling rate of -0.3 °C/min. The cooling curve or thermal history played a crucial role in the dissolution process. An exotherm (-54.7 ± 3 J/g MCC) was detected by DSC only under the slow-cooling condition, and the cryogenic dissolution of MCC was attributed to the exothermic interaction between MCC and solvent. More importantly, the low cooling rate promoted the dissolution of MCC by providing enough time for the diffusion of OH- and urea into MCC granules at higher temperatures. The Raman spectral data showed that the intramolecularly and intermolecularly hydrogen bonds in cellulose were cleaved by NaOH and urea, respectively. XPS and solid-state 13C NMR results showed that hydrogen bonds were generated after dissolution, and a dual-hydrogen-bond binding mode between urea and cellulose was confirmed by DFT calculations. Both the decrease of enthalpy and increase of entropy dominated the spontaneity of MCC dissolution, and that is the reason for the indispensability of cryogenic environment. The high apparent solubility of MCC in the slow-cooling process and the dissolution mechanism are beneficial for the studies on cellulose modification and mechanical processing.
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Affiliation(s)
- Shuo Ai
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China.
| | - Zhenhua Huang
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
| | - Wanguo Yu
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China.
| | - Chengdu Huang
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology, Liuzhou, 545006, China
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2
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Zhang M, Li P, Wang Q, Huang L, Lin K. Production of Polyhalogenated Carbazoles in Marine Red Alga Corallina officinalis: A Possible Natural Source. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:6673-6681. [PMID: 37053377 DOI: 10.1021/acs.est.3c00311] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Polyhalogenated carbazoles (PHCZs) have been increasingly detected in the environment as a result of anthropogenic and natural origin. However, it is unclear how PHCZs are naturally produced. In this study, the formation of PHCZs from bromoperoxidase (BPO)-mediated halogenation of carbazole was investigated. A total of six PHCZs were identified in reactions under different incubation conditions. The presence of Br- significantly influenced the formation of PHCZs. The products were first dominated by 3-bromocarbazole and then 3,6-dibromocarbazole as the reactions proceeded. Both bromo- and chlorocarbazoles were identified in the incubations with trace Br-, suggesting the co-occurrence of BPO-catalyzed bromination and chlorination. However, BPO-catalyzed chlorination of carbazole was much weaker than that of bromination. The formation of PHCZs could be attributable to the halogenation of carbazole by reactive halogen species generated from BPO-catalyzed oxidation of Br- and Cl- by H2O2. The halogenation was found to follow a successive substitution order of C-3, C-6, and C-1 on the carbazole ring, forming 3-, 3,6-, and 1,3,6-isomers. Similar to the incubation experiments, six PHCZs were for the first time detected in red algal samples collected from the South China Sea, China, suggesting the biogenesis of PHCZs in marine red algae. Given the widespread distribution of red algae in the marine environment, BPO-catalyzed halogenation of carbazole may be a natural origin for PHCZs.
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Affiliation(s)
- Meng Zhang
- Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Peng Li
- Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Qifang Wang
- Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Lingfeng Huang
- Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
| | - Kunde Lin
- Fujian Provincial Key Laboratory for Coast Ecology and Environmental Studies, College of the Environment and Ecology, Xiamen University, Xiamen 361102, China
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3
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Krivdin LB. Computational 1 H and 13 C NMR in structural and stereochemical studies. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:733-828. [PMID: 35182410 DOI: 10.1002/mrc.5260] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2021] [Revised: 02/14/2022] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
Present review outlines the advances and perspectives of computational 1 H and 13 C NMR applied to the stereochemical studies of inorganic, organic, and bioorganic compounds, involving in particular natural products, carbohydrates, and carbonium ions. The first part of the review briefly outlines theoretical background of the modern computational methods applied to the calculation of chemical shifts and spin-spin coupling constants at the DFT and the non-empirical levels. The second part of the review deals with the achievements of the computational 1 H and 13 C NMR in the stereochemical investigation of a variety of inorganic, organic, and bioorganic compounds, providing in an abridged form the material partly discussed by the author in a series of parent reviews. Major attention is focused herewith on the publications of the recent years, which were not reviewed elsewhere.
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Affiliation(s)
- Leonid B Krivdin
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
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4
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A 13C chemical shifts study of iodopyrazoles: experimental results and relativistic and non-relativistic calculations. Struct Chem 2021. [DOI: 10.1007/s11224-021-01755-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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5
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Núñez Alonso D, Pérez-Torralba M, Claramunt RM, Torralba MC, Delgado-Martínez P, Alkorta I, Elguero J, Roussel C. Regiospecific Synthesis and Structural Studies of 3,5-Dihydro-4 H-pyrido[2,3- b][1,4]diazepin-4-ones and Comparison with 1,3-Dihydro-2 H-benzo[ b][1,4]diazepin-2-ones. ACS OMEGA 2020; 5:25408-25422. [PMID: 33043221 PMCID: PMC7542844 DOI: 10.1021/acsomega.0c03843] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/10/2020] [Indexed: 05/12/2023]
Abstract
Nine 3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-ones (17-25), some of which contain fluoro-substituents, have been regiospecifically prepared by reaction of 2,3-diaminopyridines with ethyl aroylacetates. In two cases, open intermediates have been isolated and these are related to the reaction pathway. The X-ray crystal structure of 1-methyl-4-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (23) has been solved (formula, C15H13N3O; crystal system, monoclinic; space group, C2/c). This is an asymmetric unit constituted by a single nonplanar molecule and its conformational enantiomer due to the presence of the seven-membered diazepin-2-one moiety, which introduces a certain degree of torsion in the adjacent pyridine ring. The 1H, 13C, 15N, and 19F NMR spectra were obtained and the chemical shifts, together with those of the previously published 1,3-dihydro-2H-benzo[b][1,4]diazepin-2-ones (1-16), i.e., a total of 544 values, were successfully compared with the chemical shifts calculated at the gauge invariant atomic orbital (GIAO)/Becke, three-parameter, Lee-Yang-Parr (B3LYP)/6-311++G(d,p) level. The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido[2,3-b][1,4]diazepin-4-one (25) was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values. This allowed the determination of several structural effects. The rotation about the exocyclic N1-CR bond was also calculated and its dynamic properties were discussed.
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Affiliation(s)
- David Núñez Alonso
- Departamento
de Química Orgánica y Bio-Orgánica, Facultad
de Ciencias, UNED, Paseo Senda del Rey, 9, E-28040 Madrid, Spain
| | - Marta Pérez-Torralba
- Departamento
de Química Orgánica y Bio-Orgánica, Facultad
de Ciencias, UNED, Paseo Senda del Rey, 9, E-28040 Madrid, Spain
| | - Rosa M. Claramunt
- Departamento
de Química Orgánica y Bio-Orgánica, Facultad
de Ciencias, UNED, Paseo Senda del Rey, 9, E-28040 Madrid, Spain
| | - M. Carmen Torralba
- Departamento
de Química Inorgánica, Facultad de Ciencias Químicas, UCM, Avda. Complutense s/n, E-28040 Madrid, Spain
| | - Patricia Delgado-Martínez
- Unidad
de Difracción de Rayos X−CAI Técnicas Físicas
y Químicas, Facultad de Ciencias Químicas, UCM, Avda. Complutense s/n, E-28040 Madrid, Spain
| | - Ibon Alkorta
- Instituto
de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain
| | - José Elguero
- Instituto
de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain
| | - Christian Roussel
- Aix-Marseille
Univ., CNRS, Centrale Marseille, iSm2, 13397 Marseille, France
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6
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Vı́cha J, Novotný J, Komorovsky S, Straka M, Kaupp M, Marek R. Relativistic Heavy-Neighbor-Atom Effects on NMR Shifts: Concepts and Trends Across the Periodic Table. Chem Rev 2020; 120:7065-7103. [DOI: 10.1021/acs.chemrev.9b00785] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jan Vı́cha
- Centre of Polymer Systems, Tomas Bata University in Zlı́n, tř. Tomáše Bati 5678, CZ-76001 Zlı́n, Czechia
| | - Jan Novotný
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
| | - Stanislav Komorovsky
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84536 Bratislava, Slovakia
| | - Michal Straka
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, CZ-16610 Prague, Czechia
| | - Martin Kaupp
- Institute of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Radek Marek
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
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7
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Krivdin LB. Computational 1 H NMR: Part 1. Theoretical background. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:897-914. [PMID: 30963636 DOI: 10.1002/mrc.4873] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2019] [Revised: 03/31/2019] [Accepted: 04/01/2019] [Indexed: 06/09/2023]
Abstract
This is the first one of the three closely interrelated reviews to be published in Magnetic Resonance in Chemistry dealing with accordingly theoretical background, chemical applications, and biochemical studies of and by means of computational 1 H NMR. Presented in the first part of the review is a general outline of the modern theoretical methods and accuracy factors of computational 1 H NMR involving locally dense basis set schemes, solvent effects, vibrational corrections, and relativistic effects performed at the density functional theory and/or nonempirical levels. This review is dedicated to Prof. Stephan Sauer in view of his invaluable contribution to the field of computational nuclear magnetic resonance.
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Affiliation(s)
- Leonid B Krivdin
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
- Angarsk State Technical University, Angarsk, Russia
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8
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Alkorta I, Elguero J, Fruchier A. Theoretical study of some λ 5 -phosphinines and their NMR spectra. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:975-981. [PMID: 31339596 DOI: 10.1002/mrc.4926] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/08/2019] [Accepted: 07/17/2019] [Indexed: 06/10/2023]
Affiliation(s)
- Ibon Alkorta
- Instituto de Química Médica (CSIC), Madrid, Spain
| | - José Elguero
- Instituto de Química Médica (CSIC), Madrid, Spain
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9
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Sousa JLC, Silva AMS, Alkorta I, Elguero J. Assignment of 1 H and 13 C NMR data for three pairs of diastereomers of 4'-X benzo[1,3]cyclopropa[1,2-b]chromene-4,5-diones (X = H, OCH 3 , and Cl). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:512-521. [PMID: 31134669 DOI: 10.1002/mrc.4892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Joana L C Sousa
- Department of Chemistry & QOPNA, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Artur M S Silva
- Department of Chemistry & QOPNA, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Ibon Alkorta
- Instituto de Química Médica (IQM-CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain
| | - José Elguero
- Instituto de Química Médica (IQM-CSIC), Juan de la Cierva, 3, E-28006, Madrid, Spain
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10
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Kupka T, Gajda Ł, Stobiński L, Kołodziej Ł, Mnich A, Buczek A, Broda MA. Local aromaticity mapping in the vicinity of planar and nonplanar molecules. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:359-372. [PMID: 31034627 DOI: 10.1002/mrc.4880] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
We report on nucleus-independent magnetic shielding (NICS) scans over the centers of six- and five-membered rings in selected metal phthalocyanines (MPc) and fullerene C60 for more accurate characterization of local aromaticity in these compounds. Detailed tests were conducted on model aromatic molecules including benzene, pyrrole, indole, isoindole, and carbazole and subsequently applied to H2 Pc, ZnPc, Al(OH)Pc, and CuPc. Similar behavior of three selected magnetic probes, Bq, 3 He, and 7 Li+ , approaching perpendicularly the ring centers, was observed. For better visualization of shielding zone over the centers of aromatic rings, we introduced a simple mathematical procedure: the first and second derivatives of scan curves with respect to magnetic probe position enabled their additional examination. It allowed an easier localization of curve minimum and discrimination between areas in space varying by the magnetic field magnitude and to illustrate local aromaticity of two different kinds of rings in MPc with better resolution. Our results supported earlier reports on very low aromaticity indexes of pyrrole ring incorporated into MPc and significant aromaticity of the central macrocycle. No direct dependence between harmonic oscillator model of aromaticity and NICS was observed. Instead, a correlation between position of scan curve minimum and its magnitude were observed. In addition, the NICS values and 3 He chemical shifts in the middle of neutral C60 and C606- anion agreed well with the reported experimental NMR values for He@C60 and He@C606- .
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Affiliation(s)
- Teobald Kupka
- Faculty of Chemistry, University of Opole, Opole, Poland
| | - Łukasz Gajda
- Faculty of Chemistry, University of Opole, Opole, Poland
| | - Leszek Stobiński
- Faculty of Process and Chemical Engineering, Warsaw University of Technology, 1, Waryńskiego Street, 00-645, Warsaw, Poland
- nanoMAT Ltd., Waryńskiego 1 (FL. 4, RM. 401), 00-645, Warsaw, Poland
| | | | - Adrianna Mnich
- Faculty of Chemistry, University of Opole, Opole, Poland
| | - Aneta Buczek
- Faculty of Chemistry, University of Opole, Opole, Poland
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11
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Marín-Luna M, Claramunt RM, Nieto CI, Alkorta I, Elguero J, Reviriego F. A theoretical NMR study of polymorphism in crystal structures of azoles and benzazoles. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:275-284. [PMID: 30604430 DOI: 10.1002/mrc.4824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 12/07/2018] [Accepted: 12/25/2018] [Indexed: 06/09/2023]
Abstract
The NMR chemical shifts of two azoles and one benzazole whose crystal structures present polymorphism have been computed using the GIPAW approach. 15 N and 13 C nuclei have been studied. Statistical analysis of the computed 13 C and 15 N chemical shifts indicates that the GIPAW chemical shifts reproduce with a high degree of accuracy those experimentally reported. This methodology can be used to identify other polymorphic crystal structures.
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Affiliation(s)
- Marta Marín-Luna
- Departamento de Química Orgánica, Universidad de Vigo, Vigo, 36310, Spain
| | - Rosa M Claramunt
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED, Paseo Senda del Rey, 9, Madrid, E-28040, Spain
| | - Carla I Nieto
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED, Paseo Senda del Rey, 9, Madrid, E-28040, Spain
| | - Ibon Alkorta
- Instituto de Química Médica, CSIC, Juan de la Cierva, 3, Madrid, E-28006, Spain
| | - José Elguero
- Instituto de Química Médica, CSIC, Juan de la Cierva, 3, Madrid, E-28006, Spain
| | - Felipe Reviriego
- Instituto de Ciencia y Tecnología de Polímeros, CSIC, Juan de la Cierva, 3, Madrid, E-28006, Spain
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12
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Krivdin LB. Computational protocols for calculating 13C NMR chemical shifts. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 112-113:103-156. [PMID: 31481156 DOI: 10.1016/j.pnmrs.2019.05.004] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2019] [Revised: 05/19/2019] [Accepted: 05/20/2019] [Indexed: 06/10/2023]
Abstract
The most recent results dealing with the computation of 13C NMR chemical shifts in chemistry (small molecules, saturated, unsaturated and aromatic compounds, heterocycles, functional derivatives, coordination complexes, carbocations, and natural products) are reviewed, paying special attention to theoretical background and accuracy, the latter involving solvent effects, vibrational corrections, and relativistic effects.
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Affiliation(s)
- Leonid B Krivdin
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russia.
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13
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Kapusta K, Voronkov E, Okovytyy S, Korobov V, Leszczynski J. Reconstruction of STO-3G Family Basis Set for the Accurate Calculation of Magnetic Properties. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2019. [DOI: 10.1134/s0036024418130174] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Rusakov YY, Rusakova IL. Relativistic heavy atom effect on 13 C NMR chemical shifts initiated by adjacent multiple chalcogens. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2018; 56:716-726. [PMID: 29412478 DOI: 10.1002/mrc.4720] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 01/21/2018] [Accepted: 01/23/2018] [Indexed: 06/08/2023]
Abstract
In this paper, we have investigated the cumulative peculiarity of the "heavy atom on light atom" effect on the 13 C NMR chemical shifts, initiated by the adjacent chalcogens. For this purpose, the most accurate hybrid computational scheme for the calculation of chemical shifts of carbon nuclei, directly bonded with several heavy chalcogens, is introduced and attested on the representative series of molecules. The best hybrid scheme combines the nonrelativistic coupled cluster-based approach with the different types of corrections, including vibrational, solvent, and relativistic. The dependences of the total relativistic corrections to carbon shielding constants in 2 series of model compounds, namely, X═13 C═Y (X, Y = O, S, Se, Te) and C(XH)m (YH)n (ZH)p (QH)s H1-m H1-n H1-p H1-s (X, Y, Z, Q = S, Se, Te and m, n, p, s = 0, 1), on the total atomic number of the adjacent chalcogens have been obtained.
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Affiliation(s)
- Yu Yu Rusakov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia
| | - I L Rusakova
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033, Irkutsk, Russia
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15
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Rusakov YY, Rusakova IL, Krivdin LB. On the significant relativistic heavy atom effect on 13C NMR chemical shifts of β- and γ-carbons in seleno- and telluroketones. Mol Phys 2017. [DOI: 10.1080/00268976.2017.1350292] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- Yuriy Yu. Rusakov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
| | - Irina L. Rusakova
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
| | - Leonid B. Krivdin
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russian Federation
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16
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Kupka T, Stachów M, Stobiński L, Kaminský J. DFT study of zigzag (n, 0) single-walled carbon nanotubes: 13C NMR chemical shifts. J Mol Graph Model 2016; 67:14-9. [DOI: 10.1016/j.jmgm.2016.04.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 04/14/2016] [Accepted: 04/19/2016] [Indexed: 10/21/2022]
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17
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Radula-Janik K, Kupka T, Ejsmont K, Daszkiewicz Z, Sauer SPA. DFT and experimental studies on structure and spectroscopic parameters of 3,6-diiodo-9-ethyl-9H-carbazole. Struct Chem 2015. [DOI: 10.1007/s11224-015-0711-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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18
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Jankowska M, Kupka T, Stobiński L, Kaminský J. DFT studies on armchair (5, 5) SWCNT functionalization. Modification of selected structural and spectroscopic parameters upon two-atom molecule attachment. J Mol Graph Model 2015; 55:105-14. [DOI: 10.1016/j.jmgm.2014.11.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/19/2014] [Accepted: 11/07/2014] [Indexed: 12/01/2022]
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19
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Molecular modeling and experimental studies on structure and NMR parameters of 9-benzyl-3,6-diiodo-9H-carbazole. Struct Chem 2015. [DOI: 10.1007/s11224-014-0554-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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20
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Radula-Janik K, Kopka K, Kupka T, Ejsmont K. Substituent Effect of Nitro Group on Aromaticity of Carbazole Rings. Chem Heterocycl Compd (N Y) 2014. [DOI: 10.1007/s10593-014-1586-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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21
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Abarca B, Ballesteros R, Adam R, Ballesteros-Garrido R, Leroux FR, Colobert F, Alkorta I, Elguero J. A theoretical and experimental study of the racemization process of hexaaza[5]helicenes. Tetrahedron 2014. [DOI: 10.1016/j.tet.2014.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Nieto CI, Cabildo P, García MÁ, Claramunt RM, Alkorta I, Elguero J. An experimental and theoretical NMR study of NH-benzimidazoles in solution and in the solid state: proton transfer and tautomerism. Beilstein J Org Chem 2014; 10:1620-9. [PMID: 25161719 PMCID: PMC4142846 DOI: 10.3762/bjoc.10.168] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 06/18/2014] [Indexed: 11/23/2022] Open
Abstract
This paper reports the 1H, 13C and 15N NMR experimental study of five benzimidazoles in solution and in the solid state (13C and 15N CPMAS NMR) as well as the theoretically calculated (GIAO/DFT) chemical shifts. We have assigned unambiguously the "tautomeric positions" (C3a/C7a, C4/C7 and C5/C6) of NH-benzimidazoles that, in some solvents and in the solid state, appear different (blocked tautomerism). In the case of 1H-benzimidazole itself we have measured the prototropic rate in HMPA-d18.
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Affiliation(s)
- Carla I Nieto
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED Senda del Rey 9, E-28040 Madrid, Spain
| | - Pilar Cabildo
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED Senda del Rey 9, E-28040 Madrid, Spain
| | - M Ángeles García
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED Senda del Rey 9, E-28040 Madrid, Spain
| | - Rosa M Claramunt
- Departamento de Química Orgánica y Bio-Orgánica, Facultad de Ciencias, UNED Senda del Rey 9, E-28040 Madrid, Spain
| | - Ibon Alkorta
- Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain
| | - José Elguero
- Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain
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