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Sánchez-Sanz G, Alkorta I, Elguero J. Low Valence Triel (I) Systems as Hydrogen Bond Acceptors and their Stability with Respect to Triel (III) Compounds. Chemphyschem 2024; 25:e202400308. [PMID: 38963877 DOI: 10.1002/cphc.202400308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/28/2024] [Accepted: 07/03/2024] [Indexed: 07/06/2024]
Abstract
A theoretical study of the complexes formed by carbene like Al(I), Ga(I), In(I) and Tl(I) compounds with hydrogen bond donors (HBD), XH (HCCH, HSH,HOH, HCN, HCl, HBr, HF, and HNC) have been carried out at MP2 computational level. The isolated triel(I) compounds show a negative region of the molecular electrostatic potential region associated with the triel atom suitable to interact with electron deficient groups. This region is associated to a lone pair based on the ELF analysis and to the location of the HOMO orbital. The complexes are similar to those found in nitrogen heterocyclic carbenes (NHC) with HBD. In addition, the oxidative addition reactions of those complexes to yield the corresponding valence III compounds have been characterized. The Al(III) compounds are much more stable than the corresponding Al(I) complexes. However, the stability of the triel(III) compounds decreases with the size of the triel atom and for the thallium derivatives, the Tl(I) complexes are more stable than the Tl(III) compounds in accordance with the number of the structures found in the CSD. The barrier of the TS connecting the triel(I) and triel(III) systems increases with the size of the triel atoms.
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Affiliation(s)
- Goar Sánchez-Sanz
- Research IT, Kilburn Building, The University of Manchester, Oxford Rd, M13 9PL, Manchester, UK
| | - 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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2
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Ferrer M, Elguero J, Alkorta I, Azofra LM. Understanding the coupling of non-metallic heteroatoms to CO 2 from a Conceptual DFT perspective. J Mol Model 2024; 30:201. [PMID: 38853233 PMCID: PMC11162977 DOI: 10.1007/s00894-024-05992-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2024] [Accepted: 05/23/2024] [Indexed: 06/11/2024]
Abstract
CONTEXT A Conceptual DFT (CDFT) study has been carry out to analyse the coupling reactions of the simplest amine (CH3NH2), alcohol (CH3OH), and thiol (CH3SH) compounds with CO2 to form the corresponding adducts CH3NHCO2H, CH3OCO2H, and CH3SCO2H. The reaction mechanism takes place in a single step comprising two chemical events: nucleophilic attack of the non-metallic heteroatoms to CO2 followed by hydrogen atom transfer (HAT). According to our calculations, the participation of an additional nucleophilic molecule as HAT assistant entails important decreases in activation electronic energies. In such cases, the formation of a six-membered ring in the transition state (TS) reduces the angular stress with respect to the non-assisted paths, characterised by four-membered ring TSs. Through the analysis of the energy and reaction force profiles along the intrinsic reaction coordinate (IRC), the ratio of structural reorganisation and electronic rearrangement for both activation and relaxation energies has been computed. In addition, the analysis of the electronic chemical potential and reaction electronic flux profiles confirms that the highest electronic activity as well as their changes take place in the TS region. Finally, the distortion/interaction model using an energy decomposition scheme based on the electron density along the reaction coordinate has been carried out and the relative energy gradient (REG) method has been applied to identify the most important components associated to the barriers. METHODS The theoretical calculation were performed with Gaussian-16 scientific program. The B3LYP-D3(BJ)/aug-cc-pVDZ level was used for optimization of the minima and TSs. IRC calculations has also been carried out connecting the TS with the associated minima. Conceptual-DFT (CDFT) calculations have been carried out with the Eyringpy program and in-house code. The distortion/interaction model along the reaction coordinate have used the decomposition scheme of Mandado et al. and the analysis of the importance of each components have been done with the relative energy gradient (REG) method.
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Affiliation(s)
- Maxime Ferrer
- Instituto de Química Médica, CSIC, Juan de La Cierva,3, 28006, Madrid, Spain
- PhD Program in Theoretical Chemistry and Computational Modelling, Doctoral School, Universidad Autónoma de Madrid, 28049, Madrid, Spain
| | - José Elguero
- Instituto de Química Médica, CSIC, Juan de La Cierva,3, 28006, Madrid, Spain
| | - Ibon Alkorta
- Instituto de Química Médica, CSIC, Juan de La Cierva,3, 28006, Madrid, Spain.
| | - Luis Miguel Azofra
- Instituto de Estudios Ambientales y Recursos Naturales (iUNAT), Universidad de Las Palmas de Gran Canaria (ULPGC), Campus de Tafira, 35017, Las Palmas de Gran Canaria, Spain.
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3
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Shekhovtsov NA, Vorob'eva S, Nikolaenkova EB, Ryadun AA, Krivopalov VP, Gourlaouen C, Bushuev MB. Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms. Inorg Chem 2023; 62:16734-16751. [PMID: 37781777 DOI: 10.1021/acs.inorgchem.3c02036] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
A rare example of pyrimidine-based ESIPT-capable compounds, 2-(2-hydroxyphenyl)-4-(1H-pyrazol-1-yl)-6-methylpyrimidine (HLH), was synthesized (ESIPT─excited state intramolecular proton transfer). Its reactions with zinc(II) salts under basic or acidic conditions afforded a dinuclear [Zn2LH2Cl2] complex and an ionic (H2LH)4[ZnCl4]2·3H2O solid. Another ionic solid, (H2LH)Br, was obtained from the solution of HLH acidified with HBr. In both ionic solids, the H+ ion protonates the same pyrimidinic N atom that accepts the O-H···N intramolecular hydrogen bond in the structure of free HLH, which breaks this hydrogen bond and switches off ESIPT in these compounds. This series of compounds which includes neutral HLH molecules and ionic (LH)- and (H2LH)+ species allowed us to elucidate the impact of protonation and coordination coupled deprotonation of HLH on the photoluminescence response and on altering the emission mechanism. The neutral HLH compound exhibits yellow emission as a result of the coexistence of two radiative decay channels: (i) T1 → S0 phosphorescence of the enol form and (ii) anti-Kasha S2 → S0 fluorescence of the keto form, which if feasible due to the large S2-S1 energy gap. However, owing to the efficient nonradiative decay through an energetically favorable conical intersection, the photoluminescence quantum yield of HLH is low. Protonation or deprotonation of the HLH ligand results in the significant blue-shift of the emission bands by more than 100 nm and boosts the quantum efficiency up to ca. 20% in the case of [Zn2LH2Cl2] and (H2LH)4[ZnCl4]2·3H2O. Despite both (H2LH)4[ZnCl4]2·3H2O and (H2LH)Br have the same (H2LH)+ cation in the structures, their emission properties differ significantly, whereas (H2LH)Br shows dual emission associated with two radiative decay channels: (i) S1 → S0 fluorescence and (ii) T1 → S0 phosphorescence, (H2LH)4[ZnCl4]2·3H2O exhibits only fluorescence. This difference in the emission properties can be associated with the external heavy atom effect in (H2LH)Br, which leads to faster intersystem crossing in this compound. Finally, a huge increase in the intensity of the phosphorescence of (H2LH)Br on cooling leads to pronounced luminescence thermochromism (violet emission at 300 K, sky-blue emission at 77 K).
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Affiliation(s)
- Nikita A Shekhovtsov
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Sofia Vorob'eva
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Elena B Nikolaenkova
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, 9, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Alexey A Ryadun
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Viktor P Krivopalov
- N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences, 9, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
| | - Christophe Gourlaouen
- Laboratoire de Chimie Quantique, Institut de Chimie, UMR 7177 CNRS-Université de Strasbourg, 4 rue Blaise Pascal, Strasbourg Cedex 67070, France
| | - Mark B Bushuev
- Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Sciences, 3, Acad. Lavrentiev Ave., Novosibirsk 630090, Russia
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4
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Claramunt RM, Elguero J, Alkorta I. A theoretical study of dynamic processes observed in trimethylsilyl-1H-pyrazoles: prototropy and silylotropy. Theor Chem Acc 2022. [DOI: 10.1007/s00214-022-02936-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
AbstractThe 1H, 13C, 15N and 29Si chemical shifts of three trimethylsilyl-1H-pyrazoles were calculated and compared with literature results; the calculations were carried out at the GIAO/B3LYP/6–311 + + G(d,p) level resulting in a very good agreement that allows to predict with confidence the missing experimental values. The prototropic barrier of 4-trimethylsilyl-1H-pyrazole (1) as well as the silylotropic barriers of 1-trimethylsilyl-1H-pyrazole (2) and 1-trimethylsilyl-4-methyl-1H-pyrazole (3) were also calculated and the mechanism was established, the accordance with the experimental values being satisfactory.
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Liu J, Xuan D, Chai J, Guo D, Huang Y, Liu S, Chew YT, Li S, Zheng Z. Synthesis and Thermal Properties of Resorcinol-Furfural Thermosetting Resin. ACS OMEGA 2020; 5:10011-10020. [PMID: 32391489 PMCID: PMC7203984 DOI: 10.1021/acsomega.0c00365] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2020] [Accepted: 04/07/2020] [Indexed: 06/11/2023]
Abstract
A mild and effective synthesis of resorcinol-furfural (RF) thermosetting resin was proposed with ethanol as a distinctive solvent, which, as a usually neglected factor, was shown to not only help form a homogeneous reaction system but also observably reduce the energy barriers between the early intermediates and transition states in addition reactions by explicit solvent effects, drawn from theoretical calculation conclusions. Besides, the para-additions on aromatic rings were more dominant than ortho-additions with the same reactants, which affected the final link types of monomers verified by Fourier transform infrared spectroscopy and two-dimensional nuclear magnetic resonance tests. The prepared resin can be assigned to a relatively fast gel speed and a high residual mass (65.25%) after pyrolysis in a N2 atmosphere by adjusting the molar ratios of F to R, and the curing of that was a complex reaction, with a curing temperature around 149 °C and an activation energy of about 49.11 kJ mol-1 obtained by the Kissinger method.
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Affiliation(s)
- Jie Liu
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
| | - Dipan Xuan
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
| | - Jing Chai
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
| | - Diandian Guo
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
| | - Yuanbo Huang
- Fujian
Provincial Key Laboratory of Clean Energy Utilization and Development,
School of Mechanical and Energy Engineering, Jimei University, Xiamen 361021, P.R. China
| | - Shouqing Liu
- National
Local Joint Engineering Research Center for Efficient Utilization
of Forest Biomass Resources; Key Laboratory for Highly-Efficient Utilization
of Forest Biomass Resources in the Southwest China, National Forestry
and Grassland Administration; College of Chemical Engineering, Southwest Forestry University, Kunming 650224, P.R. China
| | - Yi Tong Chew
- School
of Energy and Chemical Engineering, Xiamen
University Malaysia, Sepang, Selangor Darul Ehsan 43900, Malaysia
| | - Shuirong Li
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
| | - Zhifeng Zheng
- Fujian
Engineering and Research Center of Clean and High-valued Technologies
for Biomass; Xiamen Key Laboratory for High-valued conversion Technology
of Agricultural Biomass; College of Energy, Xiamen University, Xiamen 361102, P.R. China
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Secrieru A, O’Neill PM, Cristiano MLS. Revisiting the Structure and Chemistry of 3(5)-Substituted Pyrazoles. Molecules 2019; 25:molecules25010042. [PMID: 31877672 PMCID: PMC6982847 DOI: 10.3390/molecules25010042] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/13/2019] [Accepted: 12/19/2019] [Indexed: 11/16/2022] Open
Abstract
Pyrazoles are known as versatile scaffolds in organic synthesis and medicinal chemistry, often used as starting materials for the preparation of more complex heterocyclic systems with relevance in the pharmaceutical field. Pyrazoles are also interesting compounds from a structural viewpoint, mainly because they exhibit tautomerism. This phenomenon may influence their reactivity, with possible impact on the synthetic strategies where pyrazoles take part, as well as on the biological activities of targets bearing a pyrazole moiety, since a change in structure translates into changes in properties. Investigations of the structure of pyrazoles that unravel the tautomeric and conformational preferences are therefore of upmost relevance. 3(5)-Aminopyrazoles are largely explored as precursors in the synthesis of condensed heterocyclic systems, namely pyrazolo[1,5-a]pyrimidines. However, the information available in the literature concerning the structure and chemistry of 3(5)-aminopyrazoles is scarce and disperse. We provide a revision of data on the present subject, based on investigations using theoretical and experimental methods, together with the applications of the compounds in synthesis. It is expected that the combined information will contribute to a deeper understanding of structure/reactivity relationships in this class of heterocycles, with a positive impact in the design of synthetic methods, where they take part.
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Affiliation(s)
- Alina Secrieru
- Center of Marine Sciences, CCMAR, Gambelas Campus, University of Algarve, UAlg, 8005-139 Faro, Portugal;
- Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK;
- Department of Chemistry and Pharmacy, Faculty of Sciences and Technology, FCT, Gambelas Campus, University of Algarve, UAlg, 8005-139 Faro, Portugal
| | | | - Maria Lurdes Santos Cristiano
- Center of Marine Sciences, CCMAR, Gambelas Campus, University of Algarve, UAlg, 8005-139 Faro, Portugal;
- Department of Chemistry and Pharmacy, Faculty of Sciences and Technology, FCT, Gambelas Campus, University of Algarve, UAlg, 8005-139 Faro, Portugal
- Correspondence: ; Tel.: +351-289-800-953
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7
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Introduction to "Intramolecular Hydrogen Bonding 2018". Molecules 2019; 24:molecules24162858. [PMID: 31394716 PMCID: PMC6720798 DOI: 10.3390/molecules24162858] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Accepted: 08/06/2019] [Indexed: 01/14/2023] Open
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8
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Alkorta I, Elguero J. Prototropic tautomerism of the addition products of N-heterocyclic carbenes to CO2, CS2, and COS. Struct Chem 2019. [DOI: 10.1007/s11224-019-01381-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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9
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Ge K, Wu Y, Wang T, Wu J. Humidity swing adsorption of H2S by fibrous polymeric ionic liquids (PILs). Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.02.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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10
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Araya-Sibaja AM, Urgellés M, Vásquez-Castro F, Vargas-Huertas F, Vega-Baudrit JR, Guillén-Girón T, Navarro-Hoyos M, Cuffini SL. The effect of solution environment and the electrostatic factor on the crystallisation of desmotropes of irbesartan. RSC Adv 2019; 9:5244-5250. [PMID: 35514656 PMCID: PMC9060688 DOI: 10.1039/c8ra10146a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Accepted: 02/04/2019] [Indexed: 12/22/2022] Open
Abstract
The experimental conditions necessary for stabilising irbesartan (IBS) tautomers in solution and selectively obtaining the desmotropic crystal forms are presented herein. 1H and 2H tautomers were stabilized in specific solution conditions and the 2H-tetrazole⋯imidazole interaction was confirmed by solution-state NMR. The results showed that highly polar and polarisable solvents (higher values of the electrostatic factor (EF)) lead to the crystallisation of IBS form B. Furthermore, the variations of pH in methanol, in turn, determined the crystallisation of desmotropes A and/or B. The experimental conditions necessary for stabilising irbesartan (IBS) tautomers in solution and selectively obtaining the desmotropic crystal forms are presented herein.![]()
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Affiliation(s)
- Andrea M Araya-Sibaja
- Laboratorio Nacional de Nanotecnología LANOTEC-CeNAT-CONARE 1174-1200 Pavas San José Costa Rica.,Centro de Investigación y Extensión en Materiales, Escuela de Ciencia e Ingeniería de los Materiales, Tecnológico de Costa Rica Cartago 159-7050 Costa Rica.,Escuela de Química, Universidad de Costa Rica San Pedro de Montes de Oca 2060 San José Costa Rica
| | - Mariola Urgellés
- Laboratorio Nacional de Nanotecnología LANOTEC-CeNAT-CONARE 1174-1200 Pavas San José Costa Rica.,Escuela de Ingeniería Química, Universidad de Costa Rica San Pedro de Montes de Oca 2060 San José Costa Rica
| | - Felipe Vásquez-Castro
- Escuela de Química, Universidad de Costa Rica San Pedro de Montes de Oca 2060 San José Costa Rica
| | - Felipe Vargas-Huertas
- Escuela de Química, Universidad de Costa Rica San Pedro de Montes de Oca 2060 San José Costa Rica
| | - José Roberto Vega-Baudrit
- Laboratorio Nacional de Nanotecnología LANOTEC-CeNAT-CONARE 1174-1200 Pavas San José Costa Rica.,Laboratorio de Investigación y Tecnología de Polímeros POLIUNA, Escuela de Química, Universidad Nacional de Costa Rica Heredia 86-3000 Costa Rica
| | - Teodolito Guillén-Girón
- Centro de Investigación y Extensión en Materiales, Escuela de Ciencia e Ingeniería de los Materiales, Tecnológico de Costa Rica Cartago 159-7050 Costa Rica
| | - Mirtha Navarro-Hoyos
- Escuela de Química, Universidad de Costa Rica San Pedro de Montes de Oca 2060 San José Costa Rica
| | - Silvia L Cuffini
- Instituto de Ciência e Técnica, Universidade Federal de São Paulo São Paulo São José dos Campos Brazil
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Abstract
A theoretical study of the substituent and solvent effects on the reaction of phosphines with CO2 has been carried out by means of Møller-Plesset (MP2) computational level calculations and continuum polarizable method (PCM) solvent models. Three stationary points along the reaction coordinate have been characterized, a pre-transition state (TS) assembly in which a pnicogen bond or tetrel bond is established between the phosphine and the CO2 molecule, followed by a transition state, and leading finally to the adduct in which the P–C bond has been formed. The solvent effects on the stability and geometry of the stationary points are different. Thus, the pnicogen bonded complexes are destabilized as the dielectric constant of the solvent increases while the opposite happens within the adducts with the P–C bond and the TSs trend. A combination of the substituents and solvents can be used to control the most stable minimum.
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12
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Campesato L, Marforio TD, Giacinto P, Calvaresi M, Bottoni A. A Full QM Computational Study of the Catalytic Mechanism of α-1,4-Glucan Lyases. Chemphyschem 2018; 19:1514-1521. [DOI: 10.1002/cphc.201701332] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Indexed: 12/16/2022]
Affiliation(s)
- Lara Campesato
- Dipartimento di Chimica “Giacomo Ciamician”; Alma Mater Studiorum - Università di Bologna; via Francesco Selmi 2 40126 Bologna Italy
| | - Tainah Dorina Marforio
- Dipartimento di Chimica “Giacomo Ciamician”; Alma Mater Studiorum - Università di Bologna; via Francesco Selmi 2 40126 Bologna Italy
| | - Pietro Giacinto
- Dipartimento di Chimica “Giacomo Ciamician”; Alma Mater Studiorum - Università di Bologna; via Francesco Selmi 2 40126 Bologna Italy
| | - Matteo Calvaresi
- Dipartimento di Chimica “Giacomo Ciamician”; Alma Mater Studiorum - Università di Bologna; via Francesco Selmi 2 40126 Bologna Italy
| | - Andrea Bottoni
- Dipartimento di Chimica “Giacomo Ciamician”; Alma Mater Studiorum - Università di Bologna; via Francesco Selmi 2 40126 Bologna Italy
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13
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Tahan A. Theoretical study addressing the effects of tautomerism and explicit/implicit water molecules on NQR and NMR parameters of tetrazole-5-thione. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:606-618. [PMID: 27930819 DOI: 10.1002/mrc.4560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Revised: 11/24/2016] [Accepted: 11/30/2016] [Indexed: 06/06/2023]
Abstract
DFT/B3LYP calculations were employed to study the effects of tautomerism and explicit/implicit water molecules on Nuclear Quadrupole Resonance (NQR) and Nuclear Magnetic Resonance (NMR) tensors of nitrogen nuclei in tetrazole-5-thione structure. The obtained results revealed that nuclear quadrupole coupling constant (χ) and isotropic chemical shielding (σiso ) values of nitrogen nuclei in tetrazole ring of five possible tautomeric forms of tetrazole-5-thione, i.e. two thione forms called tautomers A and E and three thiol forms called tautomers B, C, and D, were functions of resonance energy(E2 ) values of nitrogen lone pairs. Furthermore, it was observed that by increasing participation of lone pairs of nitrogen atoms in the ring resonance interactions, the σiso values around them were increased, while their χ and qzz values were decreased. However, the results indicated that with exception of tautomer B, the order of qzz and χ values of nitrogen nuclei in tetrazole ring was exactly opposite of the order of resonance energy values for the same nitrogen nuclei in all tautomers and their mono-hydrated complexes. In addition, a significant decrease was noticed in χ and qzz values when a water molecule was put in different positions near the tetrazole ring in tautomers A-E. The mentioned result can be attributed to hydrogen bond formation between nitrogen nuclei and the oxygen of water. In mono-hydrated complexes, the σiso values around nitrogen atoms acting as hydrogen donors in hydrogen bond formation (N-H….OH2 ) were decreased, while its values were increased for nitrogen atoms acting as hydrogen acceptors in hydrogen bond formation(N….H-OH). Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Arezoo Tahan
- Semnan Branch, Islamic Azad University, Semnan, Iran
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14
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Hajipour AR, Karimzadeh M, Ghorbani S, Farrokhpour H, Najafi Chermahini A. A comparative MP2 study between water- and acid-assisted proton transfer: allophanic acid as a case of study. Struct Chem 2016. [DOI: 10.1007/s11224-016-0753-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Prasanthkumar KP, Alvarez-Idaboy JR, Kumar PV, Singh BG, Priyadarsini KI. Contrasting reactions of hydrated electron and formate radical with 2-thio analogues of cytosine and uracil. Phys Chem Chem Phys 2016; 18:28781-28790. [DOI: 10.1039/c6cp04483b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
2-thiocytosine (TC) and 2-thiouracil (TU) were found to react with formate radical via reductive and oxidative pathways simultaneously.
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Affiliation(s)
| | - Juan R. Alvarez-Idaboy
- Departamento de Física y Química Teórica
- Facultad de Química
- Universidad Nacional Autónoma de México
- México D. F
- Mexico
| | - Pavitra V. Kumar
- Radiation and Photochemistry Division
- Chemistry Group
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - Beena G. Singh
- Radiation and Photochemistry Division
- Chemistry Group
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
| | - K. Indira Priyadarsini
- Radiation and Photochemistry Division
- Chemistry Group
- Bhabha Atomic Research Centre
- Mumbai 400085
- India
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16
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Guasch L, Peach ML, Nicklaus MC. Tautomerism of Warfarin: Combined Chemoinformatics, Quantum Chemical, and NMR Investigation. J Org Chem 2015; 80:9900-9. [PMID: 26372257 PMCID: PMC7724503 DOI: 10.1021/acs.joc.5b01370] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Warfarin, an important anticoagulant drug, can exist in solution in 40 distinct tautomeric forms through both prototropic tautomerism and ring-chain tautomerism. We have investigated all warfarin tautomers with computational and NMR approaches. Relative energies calculated at the B3LYP/6-311G++(d,p) level of theory indicate that the 4-hydroxycoumarin cyclic hemiketal tautomer is the most stable tautomer in aqueous solution, followed by the 4-hydroxycoumarin open-chain tautomer. This is in agreement with our NMR experiments where the spectral assignments indicate that warfarin exists mainly as a mixture of cyclic hemiketal diastereomers, with an open-chain tautomer as a minor component. We present a diagram of the interconversion of warfarin created taking into account the calculated equilibrium constants (pK(T)) for all tautomeric reactions. These findings help with gaining further understanding of proton transfer and ring closure tautomerization processes. We also discuss the results in the context of chemoinformatics rules for handling tautomerism.
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Affiliation(s)
- Laura Guasch
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, United States
| | - Megan L. Peach
- Basic Science Program, Chemical Biology Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, Maryland 21702, United States
| | - Marc C. Nicklaus
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Frederick, Maryland 21702, United States
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