1
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Chiari C, Batista PR, Viesser RV, Schenberg LA, Ducati LC, Linclau B, Tormena CF. Molecular dynamics and NMR reveal the coexistence of H-bond-assisted and through-space JFH coupling in fluorinated amino alcohols. Org Biomol Chem 2024; 22:2580-2595. [PMID: 38441115 DOI: 10.1039/d4ob00049h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2024]
Abstract
The JFH coupling constants in fluorinated amino alcohols were investigated through experimental and theoretical approaches. The experimental JFH couplings were only reproduced theoretically when explicit solvation through molecular dynamics (MD) simulations was conducted in DMSO as the solvent. The combination of MD conformation sampling and DFT NMR spin-spin coupling calculations for these compounds reveals the simultaneous presence of through-space (TS) and hydrogen bond (H-bond) assisted JFH coupling between fluorine and hydrogen of the NH group. Furthermore, MD simulations indicate that the hydrogen in the amino group participates in both an intermolecular bifurcated H-bond with DMSO and in transmitting the observed JFH coupling. The contribution of TS to the JFH coupling is due to the spatial proximity of the fluorine and the NH group, aided by a combination of the non-bonding transmission pathway and the hydrogen bonding pathway. The experimental JFH coupling observed for the molecules studied should be represented as 4TS/1hJFH coupling.
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Affiliation(s)
- Cassia Chiari
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
| | - Patrick R Batista
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
| | - Renan V Viesser
- Department of Chemistry, University of Houston, Houston, TX 77024, USA
| | - Leonardo A Schenberg
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil
| | - Lucas C Ducati
- Department of Fundamental Chemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes, 748, 05508-000, São Paulo, SP, Brazil
| | - Bruno Linclau
- Department of Organic and Macromolecular Chemistry, Ghent University, Ghent 9000, Belgium
| | - Cláudio F Tormena
- Institute of Chemistry, University of Campinas - UNICAMP, P. O. Box 6154, 13083-970, Campinas, São Paulo, Brazil.
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2
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Mishra SK, Suryaprakash N. Pure shift edited NMR methodologies for the extraction of Homo- and heteronuclear couplings with ultra-high resolution. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2023; 136-137:1-60. [PMID: 37716754 DOI: 10.1016/j.pnmrs.2023.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Revised: 01/20/2023] [Accepted: 02/01/2023] [Indexed: 09/18/2023]
Abstract
The scalar couplings that result in the splitting of the signals in the NMR spectrum arise due to the interaction of the nuclear spins, whereby the spin polarization is transmitted through chemical bonds. The interaction strengths depend inter alia on the number of consecutive chemical bonds intervening between the two interacting spins and on the molecular conformation. The pairwise interaction of many spins in a molecule resulting in a complex spectrum poses a severe challenge to analyse the spectrum and hence the determination of magnitudes and signs of homo- and heteronuclear couplings. The problem is more severe in the analysis of 1H spectra than the spectra of most of the other nuclei due to the often very small chemical shift dispersion. As a consequence, the straightforward analysis and the accurate extraction of the coupling constants from the 1H spectrum of a complex spin system continues to remain a challenge, and often may be a formidable task. Over the years, the several pure shift-based one-dimensional and two-dimensional methodologies have been developed by workers in the field, which provide broadband homonuclear decoupling of proton spectra, removing the complexity but at the cost of the very informative scalar couplings. To circumvent this problem, several one-dimensional and two-dimensional NMR experiments have been developed for the determination of homonuclear and heteronuclear couplings (nJHX, where n = 1,2,3) while retaining the high resolution obtained by implementing pure shift strategies. This review attempts to summarize the extensive work reported by a large number of researchers over the years for the accurate determination of homo- and heteronuclear scalar couplings.
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Affiliation(s)
- Sandeep Kumar Mishra
- Department of Physics and NMR Research Centre, Indian Institute of Science Education and Research, Pune 411008, India.
| | - N Suryaprakash
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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3
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Michalczyk M, Zierkiewicz W, Scheiner S. Crystal Structure Survey and Theoretical Analysis of Bifurcated Halogen Bonds. CRYSTAL GROWTH & DESIGN 2022; 22:6521-6530. [PMID: 36345386 PMCID: PMC9634799 DOI: 10.1021/acs.cgd.2c00726] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/26/2022] [Indexed: 06/16/2023]
Abstract
The possibility that two Lewis bases can share a single halogen atom within the context of a bifurcated halogen bond (XB) is explored first by a detailed examination of the CSD. Of the more than 22,000 geometries that fit the definition of an XB (with X = Cl, Br, I), less than 2% are bifurcated. There is a heavy weighting of I in such bifurcated arrangements as opposed to Br, which prefers monofurcated bonds. The conversion from mono to bifurcated is associated with a smaller number of short contact distances, as well as a trend toward lesser linearity. The two XBs within a bifurcated system are somewhat symmetrical: the two lengths generally differ by less than 0.05 Å, and the two XB angles are within several degrees of one another. Quantum calculations of model systems reflect the patterns observed in crystals and reinforce the idea that the negative cooperativity within a bifurcated XB weakens and lengthens each individual bond.
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Affiliation(s)
- Mariusz Michalczyk
- Faculty
of Chemistry, Wrocław University of
Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Wiktor Zierkiewicz
- Faculty
of Chemistry, Wrocław University of
Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Steve Scheiner
- Department
of Chemistry and Biochemistry, Utah State
University Logan, Logan, Utah 84322-0300, United States
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4
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Shen J, Roy A, Joshi H, Samineni L, Ye R, Tu YM, Song W, Skiles M, Kumar M, Aksimentiev A, Zeng H. Fluorofoldamer-Based Salt- and Proton-Rejecting Artificial Water Channels for Ultrafast Water Transport. NANO LETTERS 2022; 22:4831-4838. [PMID: 35674810 DOI: 10.1021/acs.nanolett.2c01137] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Here, we report on a novel class of fluorofoldamer-based artificial water channels (AWCs) that combines excellent water transport rate and selectivity with structural simplicity and robustness. Produced by a facile one-pot copolymerization reaction under mild conditions, the best-performing channel (AWC 1) is an n-C8H17-decorated foldamer nanotube with an average channel length of 2.8 nm and a pore diameter of 5.2 Å. AWC 1 demonstrates an ultrafast water conduction rate of 1.4 × 1010 H2O/s per channel, outperforming the archetypal biological water channel, aquaporin 1, while excluding salts (i.e., NaCl and KCl) and protons. Unique to this class of channels, the inwardly facing C(sp2)-F atoms being the most electronegative in the periodic table are proposed as being critical to enabling the ultrafast and superselective water transport properties by decreasing the channel's cavity and enhancing the channel wall smoothness via reducing intermolecular forces with water molecules or hydrated ions.
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Affiliation(s)
- Jie Shen
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| | - Arundhati Roy
- Department of Pharmacy, Ludwig Maximilian University Munich Butenandtstraße 5-13, Munich 81377, Germany
| | - Himanshu Joshi
- Department of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Laxmicharan Samineni
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Ruijuan Ye
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
| | - Yu-Ming Tu
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Woochul Song
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Matthew Skiles
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Manish Kumar
- McKetta Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
- Department of Civil, Architectural and Environmental Engineering, The University of Texas at Austin, Austin, Texas 78712, United States
| | - Aleksei Aksimentiev
- Department of Physics and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Huaqiang Zeng
- School of Chemistry and Chemical Engineering, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, China
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5
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Tiwari S, Arya N, Mishra SK, Suryaprakash N. Competing HB acceptors: an extensive NMR investigations corroborated by single crystal XRD and DFT calculations. RSC Adv 2021; 11:15195-15202. [PMID: 35424030 PMCID: PMC8698242 DOI: 10.1039/d1ra02538d] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 04/11/2021] [Indexed: 11/21/2022] Open
Abstract
A series of N-benzoylanthranilamide derivatives have been synthesized with the substitution of competitive HB acceptors and investigated by NMR spectroscopy and single crystal XRD. The interesting rivalry for HB acceptance between [double bond splayed left]C[double bond, length as m-dash]O and X (F or OMe) is observed in the investigated molecules which leads to an unusual increase in the electron density at the site of one of the NH protons, reflecting in the high field resonance in the 1H NMR spectrum. The NMR experimental findings and single crystal XRD are further reinforced by the DFT studies.
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Affiliation(s)
- Surbhi Tiwari
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560012 India +91 80 23601550 +91 80 23607344 +91 80 22933300 +91 98 45124802
| | - Neeru Arya
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560012 India +91 80 23601550 +91 80 23607344 +91 80 22933300 +91 98 45124802
| | - Sandeep Kumar Mishra
- Department of Physics and NMR Research Centre, Indian Institute of Science Education and Research Pune 411008 India
| | - N Suryaprakash
- NMR Research Centre and Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560012 India +91 80 23601550 +91 80 23607344 +91 80 22933300 +91 98 45124802
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6
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Scheiner S. Comparison of Bifurcated Halogen with Hydrogen Bonds. Molecules 2021; 26:molecules26020350. [PMID: 33445461 PMCID: PMC7827642 DOI: 10.3390/molecules26020350] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 01/30/2023] Open
Abstract
Bifurcated halogen bonds are constructed with FBr and FI as Lewis acids, paired with NH3 and NCH bases. The first type considered places two bases together with a single acid, while the reverse case of two acids sharing a single base constitutes the second type. These bifurcated systems are compared with the analogous H-bonds wherein FH serves as the acid. In most cases, a bifurcated system is energetically inferior to a single linear bond. There is a larger energetic cost to forcing the single σ-hole of an acid to interact with a pair of bases, than the other way around where two acids engage with the lone pair of a single base. In comparison to FBr and FI, the H-bonding FH acid is better able to participate in a bifurcated sharing with two bases. This behavior is traced to the properties of the monomers, in particular the specific shape of the molecular electrostatic potential, the anisotropy of the orbitals of the acid and base that interact directly with one another, and the angular extent of the total electron density of the two molecules.
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Affiliation(s)
- Steve Scheiner
- Department of Chemistry and Biochemistry, Utah State University, Logan, UT 84322-0300, USA
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7
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Li C, Cao Y, Hu B, Li Y. Unraveling the effect of fluorine substitution on the hydrogen bonding interaction in the complexes of fluorosubstituted pyridines and acetic acid. J PHYS ORG CHEM 2020. [DOI: 10.1002/poc.4151] [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]
Affiliation(s)
- Chaozheng Li
- School of Mechanical and Electrical Engineering Henan Institute of Science and Technology Xinxiang China
| | - Yonghua Cao
- School of Mechanical and Electrical Engineering Henan Institute of Science and Technology Xinxiang China
| | - Bo Hu
- School of Mechanical and Electrical Engineering Henan Institute of Science and Technology Xinxiang China
| | - Yongfeng Li
- School of Mechanical and Electrical Engineering Henan Institute of Science and Technology Xinxiang China
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8
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Amabili P, Calvaresi M, Martelli G, Orena M, Rinaldi S, Sgolastra F. Imidazolidinone-Tethered α-Hydrazidopeptides - Synthesis and Conformational Investigation. European J Org Chem 2019. [DOI: 10.1002/ejoc.201801427] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Paolo Amabili
- Department of Life and Environmental Sciences; Polytechnic University of Marche; Via Brecce Bianche 60131 Ancona Italy
| | - Matteo Calvaresi
- Department of Chemistry “G. Ciamician”; Alma Mater Studiorum University of Bologna; Via Selmi 2 40126 Bologna Italy
| | - Gianluca Martelli
- Department of Life and Environmental Sciences; Polytechnic University of Marche; Via Brecce Bianche 60131 Ancona Italy
| | - Mario Orena
- Department of Life and Environmental Sciences; Polytechnic University of Marche; Via Brecce Bianche 60131 Ancona Italy
| | - Samuele Rinaldi
- Department of Life and Environmental Sciences; Polytechnic University of Marche; Via Brecce Bianche 60131 Ancona Italy
| | - Federica Sgolastra
- Department of Life and Environmental Sciences; Polytechnic University of Marche; Via Brecce Bianche 60131 Ancona Italy
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9
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Arya N, Mishra SK, Suryaprakash N. Intramolecular hydrogen bond directed distribution of conformational populations in the derivatives of N′-benzylidenebenzohydrazide. NEW J CHEM 2019. [DOI: 10.1039/c9nj03071a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The extensive NMR investigations reveal the presence of E-isomers in the derivative of N′-benzylidenebenzohydrazide. The different conformer populations are controlled by the strength of intramolecular hydrogen bonds.
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Affiliation(s)
- Neeru Arya
- NMR Research Centre and Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore 560012
- India
| | - Sandeep Kumar Mishra
- NMR Research Centre and Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore 560012
- India
| | - N. Suryaprakash
- NMR Research Centre and Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore 560012
- India
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10
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Patel AK, Mishra SK, Krishnamurthy K, Suryaprakash N. Retention of strong intramolecular hydrogen bonds in high polarity solvents in binaphthalene–benzamide derivatives: extensive NMR studies. RSC Adv 2019; 9:32759-32770. [PMID: 35529738 PMCID: PMC9073135 DOI: 10.1039/c9ra07299c] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 10/07/2019] [Indexed: 11/21/2022] Open
Abstract
Advanced multidimensional NMR techniques have been employed to investigate the intramolecular hydrogen bonds (HBs) in a series of N,N′-([1,1′-binaphthalene]-2,2′-diyl)bis(benzamide) derivatives, with the site-specific substitution of different functional groups. The existence of intramolecular HBs and the elimination of any molecular aggregation and possible intermolecular HBs are ascertained by various experimental NMR techniques, including solvent polarity dependent modifications of HB strengths. In the fluorine substituted derivative, direct evidence for the engagement of organic fluorine in HB is obtained by the detection of heteronuclear through-space correlation and the coupling between two NMR active nuclei where the transmission of spin polarization is mediated through HBs (1hJFH). The extent of reduction in the strength of 1hJFH on dilution with high polarity solvents directly provided the qualitative measure of HB strength. The HB, although becoming weakened, does not get nullified even in pure high polarity solvent, which is attributed to the structural constraints. The rate of exchange of a labile hydrogen atom with the deuterium of the solvent permitted the measurement of their half-lives, that are correlated to the relative strengths of HBs. The experimental NMR findings are further validated by XRD and DFT-based theoretical computations, such as, NCI and QTAIM. NMR studies reveal very strong hydrogen bond unbreakable even in high polarity solvents.![]()
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Affiliation(s)
- Arun Kumar Patel
- Solid State and Structural Chemistry Unit and NMR Research Centre
- Indian Institute of Science
- Bangalore 560012
- India
- NMR Research Centre
| | | | | | - N. Suryaprakash
- Solid State and Structural Chemistry Unit and NMR Research Centre
- Indian Institute of Science
- Bangalore 560012
- India
- NMR Research Centre
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11
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Dhanishta P, Sai Siva Kumar P, Mishra SK, Suryaprakash N. Intramolecular hydrogen bond directed stable conformations of benzoyl phenyl oxalamides: unambiguous evidence from extensive NMR studies and DFT-based computations. RSC Adv 2018; 8:11230-11240. [PMID: 35541562 PMCID: PMC9079047 DOI: 10.1039/c8ra00357b] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 03/09/2018] [Indexed: 12/02/2022] Open
Abstract
A number of benzoyl phenyl oxalamide derivatives have been synthesized and characterized by the extensive utility of one- and two-dimensional NMR experimental techniques. The manifestation of intramolecular hydrogen bonds in all of the synthesized molecules, convincingly established using NMR studies, governs the stable conformations of the molecules. In the fluorine substituted molecules, the coupling between two NMR active nuclei mediated through hydrogen bonds has been detected. The measured chemical shift difference of an NH proton has been employed to calculate the energy of the HBs. NMR analysis revealed the electrostatic nature of the hydrogen bonds in all of the molecules. The NMR experimental findings have been validated using Density Functional Theory (DFT)-based Non Covalent Interactions (NCIs) and Quantum Theory of Atoms In Molecules (QTAIM) computations.
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Affiliation(s)
- P Dhanishta
- NMR Research Centre, Indian Institute of Science Bangalore 560 012 India +91-80-23601550 +91-80-23607344 +91-80-22933300 +91-9845124802
- Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560 012 India
| | | | - Sandeep Kumar Mishra
- NMR Research Centre, Indian Institute of Science Bangalore 560 012 India +91-80-23601550 +91-80-23607344 +91-80-22933300 +91-9845124802
- Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560 012 India
| | - N Suryaprakash
- NMR Research Centre, Indian Institute of Science Bangalore 560 012 India +91-80-23601550 +91-80-23607344 +91-80-22933300 +91-9845124802
- Solid State and Structural Chemistry Unit, Indian Institute of Science Bangalore 560 012 India
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12
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Dhanishta P, Mishra SK, Suryaprakash N. Intramolecular HB Interactions Evidenced in Dibenzoyl Oxalamide Derivatives: NMR, QTAIM, and NCI Studies. J Phys Chem A 2017; 122:199-208. [DOI: 10.1021/acs.jpca.7b10598] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- P. Dhanishta
- NMR Research Centre, Solid
State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Sandeep Kumar Mishra
- NMR Research Centre, Solid
State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - N. Suryaprakash
- NMR Research Centre, Solid
State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
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13
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Piltan M, Farshadfar K, Roe SM. Halogen Bonds Involved in Copper(I) Complexes: A Study Based on the Electronic Charge Density. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201700369] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Mohammad Piltan
- Department of Chemistry Faculty of Science, Sanandaj Branch Islamic Azad University Sanandaj Iran
| | - Kaveh Farshadfar
- Department of Chemistry Faculty of Science, Sanandaj Branch Islamic Azad University Sanandaj Iran
| | - S. Mark Roe
- Department of Chemistry School of Life Sciences University of Sussex BN1 9QJ Brighton UK
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14
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Pregosin PS. Applications of NMR diffusion methods with emphasis on ion pairing in inorganic chemistry: a mini-review. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:405-413. [PMID: 26888228 DOI: 10.1002/mrc.4394] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 11/05/2015] [Accepted: 11/11/2015] [Indexed: 06/05/2023]
Abstract
This mini-review provides a brief overview of the use of NMR diffusion methods in connection with estimating molecular weights in solution, recognizing hydrogen bonding and encapsulation processes and, primarily, identifying and estimating the varying degrees of ion pairing. Copyright © 2016 John Wiley & Sons, Ltd.
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Affiliation(s)
- Paul S Pregosin
- Laboratorium für Anorganische Chemie, ETHZ HCI, Hönggerberg, CH-8093, Zürich, Switzerland
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15
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Mishra SK, Suryaprakash N. Intramolecular Hydrogen Bonding Involving Organic Fluorine: NMR Investigations Corroborated by DFT-Based Theoretical Calculations. Molecules 2017; 22:E423. [PMID: 28272370 PMCID: PMC6155419 DOI: 10.3390/molecules22030423] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 03/02/2017] [Indexed: 01/24/2023] Open
Abstract
The combined utility of many one and two dimensional NMR methodologies and DFT-based theoretical calculations have been exploited to detect the intramolecular hydrogen bond (HB) in number of different organic fluorine-containing derivatives of molecules, viz. benzanilides, hydrazides, imides, benzamides, and diphenyloxamides. The existence of two and three centered hydrogen bonds has been convincingly established in the investigated molecules. The NMR spectral parameters, viz., coupling mediated through hydrogen bond, one-bond NH scalar couplings, physical parameter dependent variation of chemical shifts of NH protons have paved the way for understanding the presence of hydrogen bond involving organic fluorine in all the investigated molecules. The experimental NMR findings are further corroborated by DFT-based theoretical calculations including NCI, QTAIM, MD simulations and NBO analysis. The monitoring of H/D exchange with NMR spectroscopy established the effect of intramolecular HB and the influence of electronegativity of various substituents on the chemical kinetics in the number of organic building blocks. The utility of DQ-SQ technique in determining the information about HB in various fluorine substituted molecules has been convincingly established.
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Affiliation(s)
- Sandeep Kumar Mishra
- NMR Research Centre, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
| | - N Suryaprakash
- NMR Research Centre, Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India.
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16
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Mishra SK, Lokesh N, Suryaprakash N. Clean G-SERF an NMR experiment for the complete eradication of axial peaks and undesired couplings from the complex spectrum. RSC Adv 2017. [DOI: 10.1039/c6ra25617a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Clean-G-SERF spectrum is free from axial peaks and undesired couplings and is very useful in the measurement of proton–proton couplings.
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Affiliation(s)
- Sandeep Kumar Mishra
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012
- India
| | - N. Lokesh
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012
- India
| | - N. Suryaprakash
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012
- India
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17
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Mishra SK, Suryaprakash N. Organic fluorine involved intramolecular hydrogen bonds in the derivatives of imides: NMR evidence corroborated by DFT based theoretical calculations. RSC Adv 2015. [DOI: 10.1039/c5ra19537c] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The rare occurrence of intramolecular hydrogen bonds (HBs) of the type N–H⋯F–C is detected in the derivatives of imides in a low polarity solvent by using multi-dimensional and multinuclear NMR experiments.
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Affiliation(s)
- Sandeep Kumar Mishra
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012
- India
| | - N. Suryaprakash
- NMR Research Centre
- Solid State and Structural Chemistry Unit
- Indian Institute of Science
- Bangalore-560012
- India
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