1
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McGinness K, Minton K, White K, Bond MR. Bis(2-chloro- N, N-di-methyl-ethan-1-aminium) tetra-chlorido-cobaltate(II) and tetra-chlorido-zincate(II). Acta Crystallogr E Crystallogr Commun 2024; 80:577-581. [PMID: 38845718 PMCID: PMC11151309 DOI: 10.1107/s2056989024003955] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2024] [Accepted: 04/30/2024] [Indexed: 06/09/2024]
Abstract
The few examples of structures containing the 2-chloro-N,N-di-methyl-ethan-1-aminium or 3-chloro-N,N-di-methyl-propan-1-aminium cations show a compet-ition between gauche and anti conformations for the chloro-alkyl chain. To explore further the conformational landscape of these cations, and their possible use as mol-ecular switches, the title salts, (C4H11ClN)2[CoCl4] and (C4H11ClN)2[ZnCl4], were prepared and structurally characterized. Details of both structures are in close agreement. The inorganic complex exhibits a slightly flattened tetra-hedral geometry that likely arises from bifurcated N-H hydrogen bonds from the organic cations. The alkyl chain of the cation is disordered between gauche and anti conformations with the gauche conformation occupancy refined to 0.707 (2) for the cobaltate. The gauche conformation places the terminal Cl atom at a tetra-hedral face of the inorganic complex with a contact distance of 3.7576 (9) Å to the Co2+ center. The anti conformation places the terminal Cl atom at a contact distance to a neighboring anti conformation terminal Cl atom that is ∼1 Å less than the sum of the van der Waals radii. Thus, if the anti conformation is present at a site, then the nearest neighbor must be gauche. DFT geometry optimizations indicate the gauche conformation is more stable in vacuo by 0.226 eV, which reduces to 0.0584 eV when calculated in a uniform dielectric. DFT geometry optimizations for the unprotonated mol-ecule indicate the anti conformation is stabilized by 0.0428 eV in vacuo, with no strongly preferred conformation in uniform dielectric, to provide support to the notion that this cation could function as a mol-ecular switch via deprotonation.
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Affiliation(s)
- Katelyn McGinness
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
| | - Kim Minton
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
| | - Katelyn White
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
| | - Marcus R. Bond
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
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2
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TOYOTA S. Discovery of internal rotation and conformers of 1,2-dichloroethane: the dawn of the concept of conformation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2024; 100:101-113. [PMID: 38346751 PMCID: PMC10978969 DOI: 10.2183/pjab.100.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Accepted: 10/13/2023] [Indexed: 02/15/2024]
Abstract
In 1932, Mizushima and Higasi reported the dependence of the dipole moments of 1,2-dichloroethane on both temperature and solvent in the Proceedings of the Imperial Academy, Japan. This report was followed by their first proposal of the existence of conformers that exchanged by internal rotation about a C-C single bond based on experimental data. Their monumental work marked the beginning of the essential concept of conformation in modern stereochemistry. Their proposal was later confirmed by the direct observation of the anti and gauche conformers of 1,2-dichloroethane by Raman spectroscopy, and further supported by other experimental and theoretical methods. The relative stabilities of the anti and gauche conformers of 1,2-dichloroethane and other 1,2-disubstituted ethanes were discussed in terms of steric, electrostatic, and stereoelectronic effects based on analysis of calculated data. Those studies influenced the development of subsequent research in organic chemistry, such as the conformational analysis of cyclohexane derivatives and the isolation of chiral gauche conformers.
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Affiliation(s)
- Shinji TOYOTA
- Department of Chemistry, School of Science, Tokyo Institute of Technology, Tokyo, Japan
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3
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Stylianakis I, Zervos N, Lii JH, Pantazis DA, Kolocouris A. Conformational energies of reference organic molecules: benchmarking of common efficient computational methods against coupled cluster theory. J Comput Aided Mol Des 2023; 37:607-656. [PMID: 37597063 PMCID: PMC10618395 DOI: 10.1007/s10822-023-00513-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 06/03/2023] [Indexed: 08/21/2023]
Abstract
We selected 145 reference organic molecules that include model fragments used in computer-aided drug design. We calculated 158 conformational energies and barriers using force fields, with wide applicability in commercial and free softwares and extensive application on the calculation of conformational energies of organic molecules, e.g. the UFF and DREIDING force fields, the Allinger's force fields MM3-96, MM3-00, MM4-8, the MM2-91 clones MMX and MM+, the MMFF94 force field, MM4, ab initio Hartree-Fock (HF) theory with different basis sets, the standard density functional theory B3LYP, the second-order post-HF MP2 theory and the Domain-based Local Pair Natural Orbital Coupled Cluster DLPNO-CCSD(T) theory, with the latter used for accurate reference values. The data set of the organic molecules includes hydrocarbons, haloalkanes, conjugated compounds, and oxygen-, nitrogen-, phosphorus- and sulphur-containing compounds. We reviewed in detail the conformational aspects of these model organic molecules providing the current understanding of the steric and electronic factors that determine the stability of low energy conformers and the literature including previous experimental observations and calculated findings. While progress on the computer hardware allows the calculations of thousands of conformations for later use in drug design projects, this study is an update from previous classical studies that used, as reference values, experimental ones using a variety of methods and different environments. The lowest mean error against the DLPNO-CCSD(T) reference was calculated for MP2 (0.35 kcal mol-1), followed by B3LYP (0.69 kcal mol-1) and the HF theories (0.81-1.0 kcal mol-1). As regards the force fields, the lowest errors were observed for the Allinger's force fields MM3-00 (1.28 kcal mol-1), ΜΜ3-96 (1.40 kcal mol-1) and the Halgren's MMFF94 force field (1.30 kcal mol-1) and then for the MM2-91 clones MMX (1.77 kcal mol-1) and MM+ (2.01 kcal mol-1) and MM4 (2.05 kcal mol-1). The DREIDING (3.63 kcal mol-1) and UFF (3.77 kcal mol-1) force fields have the lowest performance. These model organic molecules we used are often present as fragments in drug-like molecules. The values calculated using DLPNO-CCSD(T) make up a valuable data set for further comparisons and for improved force field parameterization.
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Affiliation(s)
- Ioannis Stylianakis
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece
| | - Nikolaos Zervos
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece
| | - Jenn-Huei Lii
- Department of Chemistry, National Changhua University of Education, Changhua City, Taiwan
| | - Dimitrios A Pantazis
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Antonios Kolocouris
- Department of Medicinal Chemistry, Faculty of Pharmacy, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, 15771, Athens, Greece.
- Laboratory of Medicinal Chemistry, Section of Pharmaceutical Chemistry, Department of Pharmacy, National and Kapodistrian University of Athens, Panepistimiopolis-Zografou, 15771, Athens, Greece.
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Emenike BU, Farshadmand A, Zeller M, Roman AJ, Sevimler A, Shinn DW. Electrostatic CH-π Interactions Can Override Fluorine Gauche Effects To Exert Conformational Control. Chemistry 2023; 29:e202203139. [PMID: 36286329 DOI: 10.1002/chem.202203139] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Indexed: 11/07/2022]
Abstract
Fluorine gauche effects are conformational properties of 2-fluoroethanes often applied in modern molecular designs. However, the physical origins of fluorine gauche effects are not well understood, with the consensus favoring the established hyperconjugation theory over an emerging electrostatic model. Using a series of model systems, we show that a shift to fluorine gauche effects can be influenced by intramolecular CH⋅⋅⋅π aromatic interactions, a through-space event. Modulating the π-ring (forming the aromatic interaction) with substituent groups resulted in a linear Hammett relationship, thus indicating that the CH⋅⋅⋅π interaction has electrostatic features. For instance, attaching a nitro group (an electron-withdrawing substituent) to the π-ring weakened the CH⋅⋅⋅π interaction and led to a gauche preference, whereas an anti conformer is preferred with amine as substituent. The experimental results performed by using proton NMR spectroscopy are corroborated by gas-phase DFT calculations and solid-state X-ray crystallography.
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Affiliation(s)
- Bright U Emenike
- Department of Chemistry & Physics, State University of New York, Old Westbury, 223 Store Hill Road, Old Westbury, NY 11568, USA
| | - Amiel Farshadmand
- Department of Chemistry & Physics, State University of New York, Old Westbury, 223 Store Hill Road, Old Westbury, NY 11568, USA
| | - Matthias Zeller
- Department of Chemistry, Purdue University, West Lafayette, IN 47907-2084, USA
| | - Armando J Roman
- Department of Chemistry & Physics, State University of New York, Old Westbury, 223 Store Hill Road, Old Westbury, NY 11568, USA
| | - Arzu Sevimler
- Department of Chemistry & Physics, State University of New York, Old Westbury, 223 Store Hill Road, Old Westbury, NY 11568, USA
| | - David W Shinn
- Department of Mathematics and Science, United States Merchant Marine Academy, 300 Steamboat Road, Kings Point, NY 11024, USA
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Armstrong BI, Willans M, Pearson EL, Becker T, Hackett MJ, Raiteri P. Revisiting the Conformational Isomerism of Dihaloethanes: A Hybrid Computational and Experimental Laboratory for the Undergraduate Curriculum. ACS PHYSICAL CHEMISTRY AU 2023; 3:157-166. [PMID: 36968445 PMCID: PMC10037444 DOI: 10.1021/acsphyschemau.2c00055] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 01/13/2023]
Abstract
The conformational isomerism of disubstituted ethanes is a well-known concept that is part of every chemistry curriculum. Due to the species' simplicity, studying the (free) energy difference between the gauche and anti isomers has been the testing ground of experimental and computational techniques, such as Raman and IR spectroscopy, quantum chemistry, and atomistic simulations. While students normally receive formal training in spectroscopic techniques during their early undergraduate years, computational methods often receive less attention. In this work, we revisit the conformational isomerism of 1,2-dichloroethane and 1,2-dibromoethane and design a hybrid computational and experimental laboratory for our undergraduate chemistry curriculum with a focus on introducing computational techniques as a complementary research tool to experimentation. We show how commonly available Raman spectrometers and atomistic simulations performed on desktop computers can be combined to study the conformational isomerism of disubstituted ethanes while discussing the advantages and limitations of the different approaches.
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Affiliation(s)
- Blake I. Armstrong
- School of Molecular and Life Sciences and Curtin Institute for Computation, Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
| | - Meg Willans
- School of Molecular and Life Sciences and Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
| | - Emma L. Pearson
- School of Molecular and Life Sciences and Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
| | - Thomas Becker
- School of Molecular and Life Sciences and Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
| | - Mark J. Hackett
- School of Molecular and Life Sciences and Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
| | - Paolo Raiteri
- School of Molecular and Life Sciences and Curtin Institute for Computation, Curtin University, PO Box U1987, Perth, Western Australia6845, Australia
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6
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Bond MR, Silwal S. 3-Chloro- N, N-di-methyl-propan-1-aminium chloride. IUCRDATA 2023; 8:x230015. [PMID: 36794055 PMCID: PMC9912320 DOI: 10.1107/s2414314623000159] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
The organic cation in the title mol-ecular salt, C5H13NCl+·Cl-, exhibits the gauche effect with a C-H bond of the C atom β to the chloro group donating electrons to the anti-bonding orbital of the C-Cl bond to stabilize the gauche conformation [Cl-C-C-C = -68.6 (6)°], as confirmed by DFT geometry optimizations that show a lengthening of the C-Cl bond relative to that of the anti conformation. Of further inter-est is the higher point group symmetry of the crystal (), compared that of the that of the mol-ecular cation, which arises from a supra-molecular head-to-tail square arrangement of four mol-ecular cations that circulate in a counterclockwise direction when viewed down the tetra-gonal c axis.
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Affiliation(s)
- Marcus R. Bond
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
| | - Sajan Silwal
- Department of Chemistry and Physics, Southeast Missouri State University, Cape Girardeau, MO 63701, USA
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7
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Kil YS, Baral A, Jeong BS, Laatikainen P, Liu Y, Han AR, Hong MJ, Kim JB, Choi H, Park PH, Nam JW. Combining NMR and MS to Describe Pyrrole-2-Carbaldehydes in Wheat Bran of Radiation. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2022; 70:13002-13014. [PMID: 36167496 DOI: 10.1021/acs.jafc.2c04771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) are indispensable analytical tools to provide chemical fingerprints in metabolomics studies. The present study evaluated radiation breeding wheat lines for chemical changes by non-targeted NMR-based metabolomics analysis of bran extracts. Multivariate analysis following spectral binning suggested pyrrole-2-carbaldehydes as chemical markers of four mutant lines with distinct NMR fingerprints in a δH range of 9.28-9.40 ppm. Further NMR and MS data analysis, along with chromatographic fractionation and synthetic preparation, aimed at structure identification of marker metabolites and identified five pyrrole-2-carbaldehydes. Quantum-mechanical driven 1H iterative full spin analysis (QM-HiFSA) on synthetic pyrrole-2-carbaldehydes provided a precise description of complex peak patterns. Biological evaluation of pyrrole-2-carbaldehydes was performed with nine synthetic products, and six compounds showed hepatoprotective effects via modulation of reactive oxygen species production. Given that three out of five identified in wheat bran of radiation were described for hepatoprotective activity, the value of radiation mutation to greatly enhance pyrrole-2-carbaldehyde production was supported.
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Affiliation(s)
- Yun-Seo Kil
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
| | - Ananda Baral
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
- Research Institute of Cell Culture, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
| | - Byeong-Seon Jeong
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
| | | | - Yang Liu
- Product Quality & Analytical Method Department, United States Pharmacopeial Convention, Rockville, Maryland 20852, United States
| | - Ah-Reum Han
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 56212, South Korea
| | - Min-Jeong Hong
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 56212, South Korea
| | - Jin-Baek Kim
- Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup-si, Jeollabuk-do 56212, South Korea
| | - Hyukjae Choi
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
- Research Institute of Cell Culture, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
| | - Pil-Hoon Park
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
| | - Joo-Won Nam
- College of Pharmacy, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
- Research Institute of Cell Culture, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do 38541, South Korea
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8
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Martins FA, de Azevedo Santos L, Rodrigues Silva D, Fonseca Guerra C, Bickelhaupt FM, Freitas MP. Iodine Gauche Effect Induced by an Intramolecular Hydrogen Bond. J Org Chem 2022; 87:11625-11633. [PMID: 35984736 DOI: 10.1021/acs.joc.2c01258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The gauche conformer in 1-X,2-Y-disubstituted ethanes, that is, the staggered orientation in which X and Y are in closer contact, is only favored for relatively small substituents that do not give rise to large X···Y steric repulsion. For more diffuse substituents, weakly attractive orbital interactions between antiperiplanar bonds (i.e., hyperconjugation) cannot overrule the repulsive forces between X and Y. Our quantum chemical analyses of the rotational isomerism of XCH2CH2Y (X = F, OH; Y = I) at ZORA-BP86-D3(BJ)/QZ4P reveal that indeed the anti conformer is generally favored due to a less destabilizing I···F and I···O-H steric repulsion. The only case when the gauche conformer is preferred is when the hydroxyl hydrogen is oriented toward the iodine atom in the 2-iodoethanol. This is because of the significantly stabilizing covalent component of the I···H-O intramolecular hydrogen bond. Therefore, we show that strong intramolecular interactions can overcome the steric repulsion between bulky substituents in 1,2-disubstituted ethanes and cause the gauche effect. Our quantum chemical computations have guided nuclear magnetic resonance experiments that confirm the increase in the gauche population as X goes from F to OH.
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Affiliation(s)
- Francisco A Martins
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
| | - Lucas de Azevedo Santos
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Daniela Rodrigues Silva
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Matheus P Freitas
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900 Lavras, Minas Gerais, Brazil
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9
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Martins FA, Chagas P, Thomasi SS, Oliveira LCA, Diniz R, Freitas MP. Theoretical and X-ray evidence of electrostatic phosphonium anti and gauche effects. Chemphyschem 2022; 23:e202100856. [PMID: 34995018 DOI: 10.1002/cphc.202100856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 12/21/2021] [Indexed: 11/12/2022]
Abstract
Sulfur, not phosphorus, is the only known third-row element capable of experiencing an electrostatic gauche effect with fluorine. Some six-membered rings containing an endocyclic phosphorus atom and a β-fluorine substituent that can interconvert to axial ( gauche relative to phosphorus) and equatorial positions were then analysed. While phosphines do not establish an electrostatic attraction between fluorine and phosphorus, some oxidised forms exhibit surprising stability for the sterically disfavoured axial orientation. Because the nature of this behaviour was not obvious, since an intramolecular hydrogen bond can appear, a phosphonium derivative was further studied and its axial conformation was found to be highly stable. A preference for the gauche arrangement appears even for the acyclic and sterically hindered (2-fluoroethyl)triphenylphosphonium cation. On the other hand, (ethane-1,2-diyl)bis(phosphonium) cations are exclusively in anti conformation due to an (+/+)-electrostatic repulsion between the positively charged phosphonium groups.
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Affiliation(s)
- Francisco A Martins
- Federal University of Lavras: Universidade Federal de Lavras, Chemistry, Av. Lagoa Azul, Casa, Lavras, 37200-900, Lavras, BRAZIL
| | | | - Sérgio S Thomasi
- Federal University of Lavras: Universidade Federal de Lavras, Chemistry, BRAZIL
| | | | - Renata Diniz
- Universidade Federal de Minas Gerais, Chemistry, BRAZIL
| | - Matheus P Freitas
- Federal University of Lavras, Department of Chemsitry, Campus UFLA, CP 3037, 37200-000, Lavras, BRAZIL
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10
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Fernandes DDS, Lago ADF, Thomasi SS, Freitas MP. Conformational analysis of halobenzaldehydes: A theoretical and spectroscopic study. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2021.131005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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de Azevedo Santos L, Cesario D, Vermeeren P, van der Lubbe SCC, Nunzi F, Fonseca Guerra C. σ-Electrons Responsible for Cooperativity and Ring Equalization in Hydrogen-Bonded Supramolecular Polymers. Chempluschem 2021; 87:e202100436. [PMID: 34709769 DOI: 10.1002/cplu.202100436] [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: 09/29/2021] [Revised: 10/18/2021] [Indexed: 11/08/2022]
Abstract
We have quantum chemically analyzed the cooperative effects and structural deformations of hydrogen-bonded urea, deltamide, and squaramide linear chains using dispersion-corrected density functional theory at BLYP-D3(BJ)/TZ2P level of theory. Our purpose is twofold: (i) reveal the bonding mechanism of the studied systems that lead to their self-assembly in linear chains; and (ii) rationalize the C-C bond equalization in the ring moieties of deltamide and squaramide upon polymerization. Our energy decomposition and Kohn-Sham molecular orbital analyses reveal cooperativity in all studied systems, stemming from the charge separation within the σ-electronic system by charge transfer from the carbonyl oxygen lone pair donor orbital of one monomer towards the σ* N-H antibonding acceptor orbital of the neighboring monomer. This key orbital interaction causes the C=O bonds to elongate, which, in turn, results in the contraction of the adjacent C-C single bonds that, ultimately, makes the ring moieties of deltamide and squaramide to become more regular. Notably, the π-electron delocalization plays a much smaller role in the total interaction between the monomers in the chain.
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Affiliation(s)
- Lucas de Azevedo Santos
- Department of Theoretical Chemistry, Amsterdam Institute for Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081, HV Amsterdam, The Netherlands
| | - Diego Cesario
- Department of Theoretical Chemistry, Amsterdam Institute for Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081, HV Amsterdam, The Netherlands
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, I-06123, Perugia, Italy
| | - Pascal Vermeeren
- Department of Theoretical Chemistry, Amsterdam Institute for Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081, HV Amsterdam, The Netherlands
| | - Stephanie C C van der Lubbe
- Department of Theoretical Chemistry, Amsterdam Institute for Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081, HV Amsterdam, The Netherlands
| | - Francesca Nunzi
- Department of Chemistry, Biology and Biotechnology, University of Perugia, Via Elce di Sotto 8, I-06123, Perugia, Italy
- Istituto di Scienze e Tecnologie Chimiche "Giulio Natta" (CNR-SCITEC), Via Elce di Sotto 8, 06123, Perugia, Italy
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute for Molecular and Life Sciences (AIMMS) Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081, HV Amsterdam, The Netherlands
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Einsteinweg 55, 2333, CC Leiden, The Netherlands
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12
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Rodrigues Silva D, de Azevedo Santos L, Hamlin TA, Bickelhaupt FM, P Freitas M, Fonseca Guerra C. Dipolar repulsion in α-halocarbonyl compounds revisited. Phys Chem Chem Phys 2021; 23:20883-20891. [PMID: 34528039 PMCID: PMC8479779 DOI: 10.1039/d1cp02502c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The concept of dipolar repulsion has been widely used to explain several phenomena in organic chemistry, including the conformational preferences of carbonyl compounds. This model, in which atoms and bonds are viewed as point charges and dipole moment vectors, respectively, is however oversimplified. To provide a causal model rooted in quantitative molecular orbital theory, we have analyzed the rotational isomerism of haloacetaldehydes OHC–CH2X (X = F, Cl, Br, I), using relativistic density functional theory. We have found that the overall trend in the rotational energy profiles is set by the combined effects of Pauli repulsion (introducing a barrier around gauche that separates minima at syn and anti), orbital interactions (which can pull the anti minimum towards anticlinal to maximize hyperconjugation), and electrostatic interactions. Only for X = F, not for X = Cl–I, electrostatic interactions push the preference from syn to anti. Our bonding analyses show how this trend is related to the compact nature of F versus the more diffuse nature of the heavier halogens. Beyond point charges! The point charge concept within dipolar repulsion model is valid for compact atoms like fluorine. This model breaks down for larger halogens, for which the electrostatic attraction between nuclei and charge densities dominates.![]()
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Affiliation(s)
- Daniela Rodrigues Silva
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. .,Departamento de Química, Instituto de Ciências Naturais, Universidade Federal de Lavras, 37200-900, Lavras, MG, Brazil.
| | - Lucas de Azevedo Santos
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. .,Departamento de Química, Instituto de Ciências Naturais, Universidade Federal de Lavras, 37200-900, Lavras, MG, Brazil.
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
| | - F Matthias Bickelhaupt
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. .,Institute for Molecules and Materials (IMM), Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Matheus P Freitas
- Departamento de Química, Instituto de Ciências Naturais, Universidade Federal de Lavras, 37200-900, Lavras, MG, Brazil.
| | - Célia Fonseca Guerra
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands. .,Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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13
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Port VC, Cormanich RA. There and back again: the role of hyperconjugation in the fluorine gauche effect. Phys Chem Chem Phys 2021; 23:17329-17337. [PMID: 34346435 DOI: 10.1039/d1cp02806e] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The origin of the fluorine gauche effect has been debated for decades and recently different interpretations have been raised in the scientific community as new computational methods emerged and were applied to rationalize 1,2-difluoroethane (DFE) gauche preference. In this context, we revisited 1,2-difluoroethane (DFE) and its chlorine and bromine derivative conformational preferences through a comparative approach: the conformational behavior and hyperconjugative, steric and electrostatic contributions for the internal rotational barrier of DFE were compared with several analogue backbones, such as peroxides, disulfides and ammonia boranes. By using the Natural Bond Orbital (NBO) analysis it was found that hyperconjugation is the driving force of the conformational preference in DFE and its chlorine and bromine analogues. Electrostatics was found to be negligible and steric effects played a minor role in general, but are important in ClCH2CH2Cl and BrCH2CH2Br to counterbalance gauche stabilization by hyperconjugation and for the preference of the anti conformer.
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Affiliation(s)
- Vinicius C Port
- University of Campinas, Chemistry Institute, Monteiro Lobato Street, Campinas, Sao Paulo 13083-862, Brazil.
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14
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Martins FA, Freitas MP. An examination of the relationship between molecular dipole moment and blood-gas partition for common anaesthetic gases. Org Biomol Chem 2021; 19:6665-6670. [PMID: 34271574 DOI: 10.1039/d1ob01067k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The solubility of inhalational anaesthetics in the bloodstream is related to the minimum alveolar concentration (MAC), which is an indicator of anaesthetic gas potency. The blood-gas partition coefficient (Kbg) is a measure of how much anaesthetics bind to plasma proteins in the blood compared to air. Just like the octanol-water partition coefficient, the Kbg may be related to the molecular dipole moment (μ), which can be modulated by the molecular conformation. Our quantum-chemical calculations demonstrated that subtle stereoelectronic interactions, namely those responsible for the anomeric and gauche effects, control the conformational equilibrium of some widely used volatile fluorinated anaesthetics and, consequently, of their molecular dipole moments. Since a remarkable correlation between empirical Kbg and calculated μ was found for these anaesthetics, the average molecular dipole moments may be used to predict the anaesthetic gas potency and other properties, such as lipid solubility, of inhalational anaesthetic analogs.
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Affiliation(s)
- Francisco A Martins
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900, Lavras, MG, Brazil.
| | - Matheus P Freitas
- Department of Chemistry, Institute of Natural Sciences, Federal University of Lavras, 37200-900, Lavras, MG, Brazil.
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15
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Datta S, Limpanuparb T. Steric effects vs. electron delocalization: a new look into the stability of diastereomers, conformers and constitutional isomers. RSC Adv 2021; 11:20691-20700. [PMID: 35479364 PMCID: PMC9033979 DOI: 10.1039/d1ra02877d] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 05/24/2021] [Indexed: 01/22/2023] Open
Abstract
A quantum chemical investigation of the stability of compounds with identical formulas was carried out on 23 classes of compounds made of C, N, P, O and S atoms as core structures and halogens H, F, Cl, Br and I as substituents. All possible structures were generated and investigated by quantum mechanical methods. The prevalence of a formula in which its Z configuration, gauche conformation or meta isomer is the most stable form is calculated and discussed. Quantitative and qualitative models to explain the stability of the 23 classes of halogenated compounds were also proposed.
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Affiliation(s)
- Sopanant Datta
- Science Division, Mahidol University International College, Mahidol University Salaya Nakhon Pathom 73170 Thailand
| | - Taweetham Limpanuparb
- Science Division, Mahidol University International College, Mahidol University Salaya Nakhon Pathom 73170 Thailand
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16
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Logvinenko IG, Kondratov IS, Dobrydnev AV, Kozytskiy AV, Grygorenko OO. Synthesis and reactions of ω-CF3O-substituted aliphatic sulfonyl chlorides. J Fluor Chem 2021. [DOI: 10.1016/j.jfluchem.2021.109799] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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17
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Solel E, Ruth M, Schreiner PR. London Dispersion Helps Refine Steric A-Values: The Halogens. J Org Chem 2021; 86:7701-7713. [PMID: 33988377 DOI: 10.1021/acs.joc.1c00767] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Halogens are rarely considered as dispersion energy donors for organic reaction design. Here, we re-examine one of the textbook examples for assessing steric hindrance, the A-value, and demonstrate that even in this system, halogens cannot be treated solely as classic repulsive hard spheres. A significant part of the steric demand of the halogens is compensated by attractive London dispersion (LD) interactions, explaining the experimental lack of a clear trend when going down the halogens' row. Beyond monohalogenated cyclohexanes, dihalo- and perhalocyclohexanes also show significant LD interactions. We also explored several other small organic systems containing halogens. Our findings show that organic chemists should treat halogens as possible sources of LD interactions in reaction design, as these atoms can change the landscape of the potential energy surface and reverse trends of conformer stabilities and reaction selectivities.
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Affiliation(s)
- Ephrath Solel
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Marcel Ruth
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Peter R Schreiner
- Institute of Organic Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
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