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Journal articles on the topic 'Electron para magnetic resonance'

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Author: Grafiati

Published: 4 June 2021

Last updated: 8 February 2022

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1

Paris, S., and E. Ilisca. "Electron−Nucleus Resonances and Magnetic Field Accelerations in the Ortho−Para H2Conversion." Journal of Physical Chemistry A 103, no. 25 (June 1999): 4964–68. http://dx.doi.org/10.1021/jp990040t.

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2

Qing Jin, Chang, Liu Kun Wang, and Yany An Liu. "Magnetic resonance experiments on undoped and doped poly(para-phenylene)." Synthetic Metals 49, no. 1-3 (August 1992): 261–65. http://dx.doi.org/10.1016/0379-6779(92)90098-4.

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3

Schaefer, Ted, Rudy Sebastian, and Frank E. Hruska. "1H nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and electron delocalization in triphenylphosphine." Canadian Journal of Chemistry 71, no. 5 (May 1, 1993): 639–43. http://dx.doi.org/10.1139/v93-085.

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The 1H nuclear magnetic resonance spectral parameters are reported for triphenylphosphine as solutions in CS2/C6D12 and acetone-d6 at 300 K. The internal rotational potential opposing torsion about the P—C bond is computed by AMI and STO-3G MO methods. The computed potentials are used to calculate the average shielding of the para protons caused by the diamagnetic anisotropies of the neighbouring phenyl groups. The results are used to estimate the degree of electron delocalization from the lone pair on phosphorus. The extent of delocalization depends on the internal motions and comparisons are made with phenylphosphine. The maximum possible screening of the para protons in phenylphosphine is calculated as 0.19 ppm for a conformation in which the lone pair on phosphorus is oriented perpendicular to the aromatic plane. The intramolecular rotational potentials then yield 0.029 ppm as the shielding of the para protons in triphenylphosphine due to electron delocalization, just as found for the CS2/C6D12 solution after correction for diamagnetic anisotropy fields.

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4

Dunn, E. J., J. G. Purdon, R. A. B. Bannard, K. Albright, and E. Buncel. "Correlation of 31P nuclear magnetic resonance chemical shifts in aryl phosphinates with Hammett substituent constants: Inductive versus resonance interactions and relevance to pπ–dπ bonding." Canadian Journal of Chemistry 66, no. 12 (December 1, 1988): 3137–42. http://dx.doi.org/10.1139/v88-484.

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Substituent-induced chemical shifts and coupling constants in the 31P, 13C, and 1H nuclear magnetic resonance spectra of meta- and para-substituted phenyl dimethylphosphinates (1), methylphenylphosphinates (2), and diphenylphosphinates (3) have been determined in CDCl3 solvent. For all three series, a correlation of δ 31P with Hammett–Taft σ0 (or σ) constants is preferred over σ− on the basis of the correlation coefficient and standard deviations of the slope and intercept values. Electron-withdrawing substituents induce downfield shifts in δ 31P, in contrast to the inverse trends observed for structurally related series of oxyphosphorus acids and their derivatives. It is proposed that electron-withdrawing substituents act to deplete the electron density on the aryl oxygen, thereby weakening a pπ–dπ bonding interaction between the aryl oxygen and phosphorus. The resultants loss of d-orbital density on phosphorus causes a downfield shift in δ 31P in each of the phosphinate series. Phenyl substituents attached directly to phosphorus in series 2 and 3 increase the phosphoryl pπ–dπ back-bonding interactions, either through inductive or resonance effects, which leads to shielding of the phosphorus atom, overriding the anticipated downfield shift through inductive electron withdrawal of the phenyl substituents in series 2 and 3, relative to the methyls in series 1. Trends in Hammett ρ values for the plots of δ 31P and δ 13C versus σ0 and differences in the shielding of 13C and 1H nuclei of the methyl attached to phosphorus in series 1 and 2 suggest that the phenyl groups may interact in π bonding with the phosphorus atom through a resonance interaction.

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5

Ito, Akihiro, and Kazuyoshi Tanaka. "Macrocyclic oligoarylamine-based spin system." Pure and Applied Chemistry 82, no. 4 (March 17, 2010): 979–89. http://dx.doi.org/10.1351/pac-con-09-10-16.

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Alternating meta- and para-phenylene-linked oligoarylamines are considered as promising molecular parts for the molecule-based electronics and/or spintronics due to their intriguing electronic and magnetic properties. From the magnetic viewpoint, a -meta-phenylene linker plays a crucial role in ensuring the effective ferromagnetic interaction, while para-phenylene linker plays an important part in stabilizing the spin-containing aminium radical cations. Of the meta–para and all-meta oligoarylamines prepared so far, the macrocyclic oligoarylamines are structurally defined, and therefore we can employ them as the component pieces to prepare the two- or three-dimensionally structured oligoarylamines. The spin electronic properties of polycationic species generated from two kinds of macrocyclic oligoarylamines, which will be able to be extended into the 2D multi-spin molecular systems, are described on the basis of the pulsed electron spin resonance (ESR) measurements.

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6

Schaefer, Ted, Rudy Sebastian, and Glenn H. Penner. "1H nuclear magnetic resonance spectral parameters of toluene. Implications for conformational analysis and isotope shifts." Canadian Journal of Chemistry 63, no. 10 (October 1, 1985): 2597–600. http://dx.doi.org/10.1139/v85-431.

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A precise analysis of the 1H nmr spectrum of toluene as a dilute solution in carbon disulfide yields a revised set of spectral parameters. The chemical shift of the para proton lies 12.6 ppb to low frequency of that of the ortho protons at 300 K. The ring proton chemical shifts are discussed and compared with 1H and 3H shifts observed in carbon tetrachloride. The long-range couplings between methyl and ring protons can be said to be quantitatively understood in terms of σ and σ–π electron transmitted mechanisms. The changes observed in these three couplings in phenylacetaldehyde can be quantitatively reproduced in terms of these mechanisms and also illustrate how these changes are direct measures of the conformational preferences in this molecule.

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7

Schaefer, Ted, Scott Kroeker, and David M. McKinnon. "1H and 13C nuclear magnetic resonance and molecular orbital studies of the internal rotational potential and of spin–spin coupling transmission in phenylallene." Canadian Journal of Chemistry 73, no. 9 (September 1, 1995): 1478–87. http://dx.doi.org/10.1139/v95-183.

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The 1H nuclear magnetic resonance spectra of phenylallene, diluted in acetone-d6 and benzene-d6, yield long-range coupling constants over as many as eight formal bonds between the ring and side-chain protons. These are discussed in terms of σ- and π-electron spin–spin coupling mechanisms, which are sensitive to the torsion angle between the allenyl and phenyl fragments. The torsion angle is assessed by means of molecular orbital computations of the internal rotational potential, whose height is calculated as 16.0 kJ/mol at the MP2/6-31G* level of correlation-gradient theory. Comparison with experimental and theoretical internal rotational potentials for styrene suggests that steric repulsions in the planar form of styrene amount to about 4 kJ/mol. In a field of 7.0 T, phenylallene is partially aligned, entailing a positive dipolar coupling constant between the methylene protons, from which absolute signs of the spin–spin coupling constants involving these protons can be inferred. Such coupling constants over seven and eight bonds, to the meta and para protons, are taken as being mediated by the extended π-electron system, providing a measure of π-electron contributions to coupling constants between meta protons and those in side chains (spin correlation). Some coupling constants between protons and 13C nuclei in the side chain, as well as between ring protons and these 13C nuclei, are also discussed in terms of spin coupling mechanisms. Solvent perturbations of one-bond proton–carbon coupling constants in the allenyl group do not follow the usual pattern in which an increase in polarity of the solvent is associated with an increase in the magnitude of the coupling constant. Keywords: 1H NMR, phenylallene; 1H NMR, long-range spin–spin coupling constants in phenylallene; phenylallene, internal rotational potential, molecular orbital computations; molecular orbital calculations, an internal rotational potential in phenylallene.

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8

Steel-Goodwin, Linda, Tasha L. Pravecek, and Alasdair J. Carmichael. "Trichloroethylene metabolism in vitro: an EPR/SPIN trapping study." Human & Experimental Toxicology 15, no. 11 (November 1996): 878–84. http://dx.doi.org/10.1177/096032719601501103.

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Trichloroethylene (TCE) was hypothesized to produce free radicals which could be detected using electron para magnetic resonance spectroscopy with the spin trap, PBN (α-phenyl tert-butyl nitrone). The free radicals detected following incubation of precision cut liver slices in media containing 10 mM PBN had hyperfine coupling constants aN=1.61 mT and aH=0.325 mT. There was a linear increase in free radicals detected in the bathing media when the headspace TCE concentration was increased from 2500- 10 000 p.p.m. The levels of conjugated dienes measured in the slices incubated in PBN supplemented media were less than slices exposed to TCE in incubation media without PBN. The PBN trap may act as a scavenger preventing the propagation of free radicals and inhibiting lipid peroxida tion. The experiments suggest that free radical formation by TCE leads to a concomitant increase in conjugated dienes in liver slices which may contribute to the pathological changes which occur in liver following TCE exposure.

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9

Budi Lelono, Eko, and Isnawati Isnawati. "PERANAN IPTEK NUKLIR DALAM EKSPLORASI HIDROKARBON." Jurnal Forum Nuklir 1, no. 2 (November 1, 2007): 79. http://dx.doi.org/10.17146/jfn.2007.1.2.3274.

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Perkembangan iptek nuklir berpengaruh terhadap teknik eksplorasi hidrokarbon, antara lain terbukti dengan adanya penggunaan isotop radioaktif untuk menentukan umur absolute batuan. Penentuan umur batuan yang pada awalnya menggunakan fosil penunjuk umur (baik mikro maupun makro-fosil) yang menghasilkan umur relatif batuan, belakangan ini diperkaya dengan metode perhitungan peluruhan mineral radioaktif untuk menentukan umur absolute batuan, sehingga posisi stratigrafi suatu lapisan batuan (batuan induk dan reservoir) dapat ditentukan dengan pasti. Sementara itu, aplikasi teknologi nuklir juga dipergunakan dalam survey sumur pemboran eksplorasi yang antara lain dikenal dengan Nuclear Magnetic Resonance (NMR) yang membantu ahli geologi dalam mengukur porositas dan permiabilitas secara langsung di lapangan, sehingga dapat memprediksi keberadaan hidrokarbon. Dari sisi sedimentologi, iptek nuklir juga diaplikasikan dalam laboratorium X Ray Diffraction (XRD Laboratory) untuk menentukan jenis mineral penyusun batuan dan laboratorium Scanning Electron Microscope (SEM Laboratory) untuk mengetahui porositas batuan. Kedua hal tersebut membantu ahli eksplorasi dalam menyusun manajemen reservoir.

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10

Kuvshinova, Elizaveta M., Olga V. Gornukhina, Alexander S. Semeikin, Irina A. Vershinina, and Sergey A. Syrbu. "COORDINATION PROPERTIES OF NITRO-SUBSTITUTED 5,15-DIPHENYL-3,7,13,17-TETRAMETHYL-2,8,12,18-TETRAETHYLPORPHYRIN WITH MANGANESE ACETATE IN PYRIDINE AND ACETIC ACID." IZVESTIYA VYSSHIKH UCHEBNYKH ZAVEDENII KHIMIYA KHIMICHESKAYA TEKHNOLOGIYA 63, no. 9 (August 4, 2020): 49–55. http://dx.doi.org/10.6060/ivkkt.20206309.6218.

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The synthesis of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro substituted was carried out. Nitro groups are located in meso-positions of the tetrapyrrole macrocycle and (or) para-positions of the phenyl rings. The synthesized porphyrins are characterized by a set of modern research methods: electron absorption spectroscopy; IR and nuclear magnetic resonance spectroscopy 1H. The reactions of the formation of manganese complexes with nitro-substituted 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and their stability in organic solvents are studied. It was found that the rate of reactions of formation of manganese complexes in pyridine with the introduction of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphine grows as the degree of deformation of the tetrapyrrole macrocycle increases. Obviously, in this case, not only the stretching of NH bonds, due to the presence of electron-withdrawing substituents (NO2) in the para positions of the phenyl rings, makes a decisive contribution to the energy of the transition state, but also the increase in the basicity of tertiary nitrogen atoms, which form strong bonds in the transition state with a solvated cation of salt. In acetic acid, the macrocycle deformation effect leads to a decrease in the reaction rate, which is due to the specific solvation of the porphine reaction center by acetic acid molecules. It was found that steric distortions of the planar structure of porphyrins have relatively little effect on the kinetic parameters of the solvoprotolytic dissociation of manganese complexes of 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrin and its nitro-substituted ones. This is probably due to the fact that the coordination of the manganese cation results in a more planar structure of the porphyrin macrocycle. The decrease in the dissociation reaction rate with an increase in the number of nitrogroups in 5,15-diphenyl-3,7,13,17-tetramethyl-2,8,12,18-tetraethylporphyrine is due to the influence of the negative inductive effect of nitrogroups, which reduces the effective charge in the macrocycle on nitrogen atoms that are attacked by a solvated proton.

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11

Davidse, P. Adriaan, Jan L. M. Dillen, Anton M. Heyns, Tomasz A. Modro, and Petrus H. van Rooyen. "Photochromic systems. Part 1. Structural and spectroscopic study of photochromically active products of Stobbe condensation. 2,3-Dibenzylidenesuccinic acid and its anhydride." Canadian Journal of Chemistry 68, no. 5 (May 1, 1990): 741–46. http://dx.doi.org/10.1139/v90-117.

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E,E-2,3-Dibenzylidenesuccinic acid (2) and its anhydride (1) were synthesized, their crystal structures and 1H and 13C nuclear magnetic resonance spectra were determined, and electron charge densities of carbon atoms were calculated. These results were related to the corresponding data available for E-cinnamic acid (3) in order to evaluate the effect of structural changes in a series 3 → 2 → 1 on the molecular parameters and spectroscopic properties of the cinnamic system. In the molecule of 2 most of the steric strain is released by the rotation about the C(α)—C(α′) bond giving rise to a structure consisting of two, approximately independent, cinnamic acid moieties. In 1, severe steric strain is introduced, as demonstrated by the unusually large values of the CCC bond angles exocyclic with respect to the anhydride ring, as well as by significant deviations from the plane of the cinnamic skeleton. The geometry of 1 results in an intramolecular shielding of the aromatic hydrogen atoms due to the proximity of the two benzene rings; this shielding effect for the ortho, meta, and para hydrogen atoms correlates well with the intramolecular distances between the corresponding positions of both rings. The common linear relationship between 13C chemical shifts and the electron charge densities on the given carbon atom has been obtained for compounds 1, 2, and 3.Crystal data. Anhydride (1): space group P21/c with a = 13.536(3), b = 14.391(3), c = 7.159(1) Å; β = 98.69(1)°; Rw = 0.029 and R = 0.055. Succinic acid (2): space group [Formula: see text] with a = 8.881(3), b = 9.786(1), c = 11.355(3) Å; α = 85.56(1), β = 88.76(2), γ = 69.46(2)°; Rw = 0.048 and R = 0.081. This compound cocrystallizes with one molecule of the solvent (acetic acid). Keywords: photochromic, cinnamic, succinic.

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12

Schaefer, Ted, Rudy Sebastian, and Glenn H. Penner. "Theoretical and experimental approaches to the barrier to rotation about the Csp2—Csp3 bond in benzyl silane. Hyperconjugative stabilization of the perpendicular conformation." Canadian Journal of Chemistry 69, no. 3 (March 1, 1991): 496–502. http://dx.doi.org/10.1139/v91-074.

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The 1H nuclear magnetic resonance spectra of benzyl silane and benzyl trichlorosilane, obtained in CS2 and benzene-d6 solutions, are analyzed. The long-range coupling constants between the methylene and para ring protons are used to derive apparent twofold barriers about the Csp2—Csp3 bonds of 7.4 ± 1.6 and 8.1 ± 1.1 kJ/mol for the silane and the trichlorosilane, respectively. These are higher than that for ethylbenzene and are attributed mainly to the stabilization of the perpendicular conformer, that with the C—Si bond in a plane perpendicular to the phenyl plane, by σ–π conjugation (hyperconjugation) of the C—Si bond and the π electron system. Molecular orbital computations confirm the predominantly twofold nature of the internal barrier in benzyl silane and also for benzyl germane and stannane. The calculated barriers for the silane derivatives are rather higher than the experimental values. The computed barriers have magnitudes that appear to change with X in much the same order as do the hyperconjugative interactions deduced in other ways for CH2X(CH3)3 groups (X = Sn, Ge, Si, C). The angles CCX in benzyl-X (X = CH3, SiH3, SiCl3, GeH3, SnH3) are all computed to decrease smoothly as sin2ψ, where ψ is the angle by which the C—X bond twists out of the phenyl plane. Key words: conformations, benzyl silane and trichlorosilane; NMR, benzyl silane and trichlorosilane; MO calculations, benzyl silane and trichlorosilane.

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13

G, Adang H., Anung Pujiyanto, Abdul Mutalib, Rista A. S, Indrarini L, Rien L, Iyus M. Y, Herlan S, and Sutriyo C. "Profil Distribusi dan Klirens Pengkontras CT SCAN AuNP-PAMAM G4- NIMOTUZUMAB disimulasikan menggunakan Senyawa 198AuNP-PAMAM G4-NIMOTUZUMAB." Jurnal Kimia Terapan Indonesia 18, no. 01 (June 10, 2016): 37–43. http://dx.doi.org/10.14203/jkti.v18i01.38.

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Riset nanopartikel emas sebagai senyawa pengkontras CT-Scan telahdimulai sejak 3 tahun lalu di Indonesia. Riset interaksi antibodi monoklonal,khususnya nimotuzumab, dengan reseptor EGFR/HER1 dimulai sejak lima tahun lalu dan telah dimanfaatkan untuk penyiapan senyawa pengkontras MRI (Magnetic Resonance Imaging) spesifik target melalui pelabelan konjugat dendrimer-nimotuzumab dengan radionuklida. Sintesis senyawa AuNP-PAMAM G4-Nimotuzumab untuk diagnosis dan terapi pada kanker paru-paru telah berhasil dilakukan di PTRR dan hasil karakterisasinya dengan menggunakan beberapa metode seperti KCKT (Kromatografi Cair Kinerja Tinggi), SDS (Sodium Dodecyl Sulphate) page elektroforesa dan TEM (Transmission Electron Microscopy) menunjukkan bahwa senyawa yang terbentuk adalah sebagai AuNP-PAMAM G4-Nimotuzumab. Pada penelitian ini telah dilakukan uji pre klinis dari senyawa pengkontras AuNPPAMAM G4-nimotuzumab meliputi uji distribusi dan klirens dengan disimulasikan menggunakan senyawa radioaktiv 198AuNP-PAMAM G4- nimotuzumab. Hasil uji distribusi senyawa 198AuNP-PAMAM G4- nimotuzumab menunjukkan penimbunan pada beberapa organ seperti ginjal, hati dan limpa, sedangkan dari hasil uji klirens diperoleh waktu paruh biologis senyawa tersebut adalah 11.77 hari. Hasil pemeriksaan terhadap urin dengan menggunakan kolom PD-10 (Sephadex G25) menunjukkan bahwa ~ 85 % yang dikeluarkan lewat urin masih berbentuk AuNP-PAMAM G4- Nimotuzumab. Hasil pencitraan dengan alat autoradiography menunjukkan bahwa sampai dengan 48 jam setelah penyuntikan, akumulasi radioaktivitas yang terdeteksi masih terdapat pada hati.

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14

Sun, Jiaoxia, Xiqin Ma, Xiang Li, Jianxin Fan, Qingkong Chen, Xuelian Liu, and Jin Pan. "Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal." International Journal of Polymer Science 2018 (February 1, 2018): 1–11. http://dx.doi.org/10.1155/2018/8230965.

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A ternary cationic polyacrylamide (CPAM) with the hydrophobic characteristic was prepared through ultraviolet- (UV-) initiated polymerization technique for the estrone (E1) environmental estrogen separation and removal. The monomers of acrylamide (AM), acryloyloxyethyl-trimethyl ammonium chloride (DAC), and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC) were used to synthesize the ternary copolymer (PADA). Fourier transform infrared spectroscopy (FT-IR), 1H nuclear magnetic resonance spectroscopy (1H NMR), thermogravimetry/differential scanning calorimetry (TG/DSC), and scanning electron microscopy (SEM) were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group), an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L), an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1) was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1). The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress.

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15

Schaefer, Ted, Jeremy P. Kunkel, Robert W. Schurko, and Guy M. Bernard. "A precise analysis of the 1H nuclear magnetic resonance spectrum of 2-phenyl-1,3-dithiane. Ring pucker, signs of long-range J(H,H), internal rotational barrier, and van der Waals shifts." Canadian Journal of Chemistry 72, no. 7 (July 1, 1994): 1722–27. http://dx.doi.org/10.1139/v94-217.

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The 1H nuclear magnetic resonance spectrum of 2-phenyl-1,3-dithiane, as a dilute solution in a CS2–C6D12–TMS solvent mixture at 300 K, is analyzed to yield 8 chemical shifts and 22 distinct coupling constants, nJ(H,H), n = 2–6. The coupling constant between H-2 and the para proton indicates, first, that the bisected conformer (phenyl plane perpendicular to the pseudo plane of the dithiane ring) is most stable and, second, that the apparent twofold barrier to rotation about the Csp2—Csp3 bond is 9.6 kJ/mol. The AM1, STO-3G, and STO-3G* computations confirm the twofoldedness of the barrier; the AM1 barrier is 9.4 kJ/mol. The empirical equation, [Formula: see text] reproduces the vicinal coupling constants of the CH2CH2CH2 fragments and implies puckering angles [Formula: see text] of 54°, 61°, and 64°, respectively. It is implied that 3J at [Formula: see text] is larger than at [Formula: see text] This results is discussed in terms of the latest theoretical approach to 3J in the HCCH fragment. The 4J(H,H) signs and magnitudes for the CH2CH2CH2 fragment agree reasonably well with theory. For the CH2SCH fragment, 4J(H,H) values are positive, in contrast to corresponding numbers in the propanic fragment, perhaps the first experimental values for certain rigid orientations about a heteroatom. INDO MO FPT computations on propane, dimethyl ether, and dimethyl sulfide confirm the experimental trend in 4J(H,H). 2J(H,H) and 5J(H,H) values are compared to those in related molecules. The striking differential shifts of the axial and equatorial protons are attributed to differential van der Waals interactions with the 3p lone-pair orbital on sulfur. A comparison of the ring proton chemical shifts with those in phenylcyclohexane and isopropylbenzene implies that C—S bonds are weaker net electron donors by hyperconjugation than are C—C bonds. It is also proposed that the ortho protons are deshielded by intramolecular van der Waals interactions with the 3p orbitals on the sulfur atoms.

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16

Schaefer, Ted, Robert W. Schurko, Rudy Sebastian, and Frank E. Hruska. "Experimental and theoretical assessments of the substituent and medium dependence of the internal rotational potentials in benzyl fluoride. 3,5-Difluorobenzyl fluoride and 4-fluorobenzyl fluoride." Canadian Journal of Chemistry 73, no. 6 (June 1, 1995): 816–25. http://dx.doi.org/10.1139/v95-102.

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The 1H, 19F, and 13C {H} nuclear magnetic resonance spectra at 300 K of 4-fluoro- and 3,5-difluorobenzyl fluoride, dissolved in CS2–C6D12 and acetone-d6, are fully analyzed. Spin–spin coupling constants over four, five, and six formal bonds are used to derive expectation values of sin2θ and [Formula: see text] and the apparent twofold internal rotational potentials; [Formula: see text] is the angle by which the α C—F(C—H) bond twists out of the ring plane. The conformation of lowest energy has [Formula: see text] for the 3,5-difluoro compound in the polar and nonpolar solutions, whereas it has [Formula: see text] for the 4-fluoro derivative. The magnitudes of the potentials lie between 2 and 4 kJ/mol, that is, comparable to thermal energies. These data are compared with previous results for the parent compound and its 3,5-dichloro derivative. Geometry-optimized molecular orbital computations, including some correlation-gradient procedures, for benzyl fluoride and the two fluoro derivatives have [Formula: see text] for the conformations of highest energy of the free molecules. However, geometry-optimized SCFRF calculations of the solvent perturbations of the potential (dipole terms are insufficient) are in semiquantitative agreement with experiment in the sense that both solvents are predicted to destabilize the conformation with [Formula: see text] For example, the predominant twofold component in the computed (6-31G*) potential is 3.4 (free), −0.7 (CS2), and −3.3 (acetone-d6) kJ/mol for benzyl fluoride, a negative number indicating [Formula: see text] for the stable conformer; the experimental values are −0.8(2) (CS2) and −2.7(2) (acetone-d6) kJ/mol. The agreement between experiment and theory is of a similar quality for the fluoro derivatives. The stabilization of the conformer with [Formula: see text] for the 4-fluoro derivative is tentatively attributed to hyperconjugative electron acceptance by the α C—F bond, enhanced by the π-electron donor at the para position. A number of coupling constants are discussed in terms of the possible mechanisms of their transmission. Future experiments are indicated. Keywords: 1H, 19F, 13C NMR of 4-fluorobenzyl fluoride and 3,5-difluorobenzyl fluoride; MO calculations and internal rotational potentials in benzyl fluoride, 3,5-difluorobenzyl fluoride, and 4-fluorobenzyl fluoride; solvent effects and experimental and theoretical approaches to internal rotational potentials in 3,5-difluorobenzyl fluoride and 4-fluorobenzyl fluoride.

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17

Gourier, Didier, Laurent Binet, and Olivier Guillot-Noël. "Bistable electron magnetic resonance in solids." Comptes Rendus Chimie 7, no. 3-4 (March 2004): 293–302. http://dx.doi.org/10.1016/j.crci.2003.12.011.

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18

Buncel, Erwin, and Julian M. Dust. "Ambident reactivity in the reaction of phenoxide ion with 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, new superelectrophiles." Canadian Journal of Chemistry 66, no. 7 (July 1, 1988): 1712–19. http://dx.doi.org/10.1139/v88-277.

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Reaction of the novel superelectrophiles 2-N-(2′,4′-dinitrophenyl)- and 2-N-(4′-nitrophenyl)-4,6-dinitrobenzotriazole 1-oxides, 3, and 4, possessing two electrophilic centres, with the ambident nucleophile potassium phenoxide in (CD3)2SO was followed by 400 MHz 1H nuclear magnetic resonance spectroscopy. A dichotomy in the reaction pathways has been observed. With MeO−, attack at C-7 leads to reversible adduct formation, while attack at C-1′ results in irreversible N-2: C-1′ bond scission via the metastable C-1′ adduct. In contrast, the reaction of 3 and 4 with PhO− proceeds by a two-pronged attack: formation of C-7 carbon-bonded phenoxide adducts via the ortho and para carbon sites, and oxygen-based cleavage products by attack at the C-1′ position, accompanied by N-2:C-1′ bond scission, in accord with the ambident reactivity of PhO−. Significantly, in this case reaction of both C-7 and C-1′ is effectively irreversible. Moreover, the reaction of phenoxide with either 3 or 4 shows striking differences compared to the reaction of PhO− with 2-N-(picryl)-4,6-dinitrobenzotriazole 1-oxide, 1. Reaction of PhO− with 1 resulted only in O-attack at C-1′ and N-2:C-1′ bond scission; there was no evidence for C-7 adduct formation via O- or C-attack. This marked difference in behaviour can be attributed to the decreased susceptibility to C-1′ attack exhibited by 3 and 4 as compared to 1 and arises from the successive removal of electron-withdrawing nitro groups from the 2-N′-nitroaryl moiety in the series 1 → 3 → 4. The reactions are discussed on the basis of selectivity considerations and an activation energy/reaction coordinate profile comparing the pathways for both C-attack at C-7 and O-attack at C-l′ as electrophilicity (delocalizability) is progressively modulated in the reaction series.

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19

Webb, Andrew. "Cavity- and waveguide-resonators in electron paramagnetic resonance, nuclear magnetic resonance, and magnetic resonance imaging." Progress in Nuclear Magnetic Resonance Spectroscopy 83 (November 2014): 1–20. http://dx.doi.org/10.1016/j.pnmrs.2014.09.003.

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20

Rao, S. S., B. Padmanabhan, Suja Elizabeth, H. L. Bhat, and S. V. Bhat. "Magnetic, electron magnetic resonance and optical studies of Pr0.7Pb0.3MnO3nanoparticles." Journal of Physics D: Applied Physics 41, no. 15 (July 17, 2008): 155011. http://dx.doi.org/10.1088/0022-3727/41/15/155011.

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21

Meusinger, Reinhard, and A. Margaret Chippendale. "ChemInform Abstract: Nuclear Magnetic Resonance and Electron Spin Resonance Spectroscopy." ChemInform 32, no. 41 (May 24, 2010): no. http://dx.doi.org/10.1002/chin.200141298.

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22

Leunbach, Ib, and Drag Denmara. "4984573 Method of electron spin resonance enhanced magnetic resonance imaging." Magnetic Resonance Imaging 10, no. 3 (January 1992): I. http://dx.doi.org/10.1016/0730-725x(92)90524-4.

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23

Shames, A. I., E. Rozenberg, G. Gorodetsky, J. Pelleg, and B. K. Chaudhuri. "Electron magnetic resonance study of polycrystalline La0.5Pb0.5MnO3." Solid State Communications 107, no. 3 (May 1998): 91–95. http://dx.doi.org/10.1016/s0038-1098(98)00180-x.

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24

Dionne, Gerald F. "Magnetic exchange enhancement of electron spin resonance." Journal of Applied Physics 105, no. 7 (April 2009): 07A525. http://dx.doi.org/10.1063/1.3068424.

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25

Segev, Bilha, and Y. B. Band. "Electron magnetic resonance: the modified Bloch equation." Journal of Physics B: Atomic, Molecular and Optical Physics 35, no. 4 (February 13, 2002): 1085–94. http://dx.doi.org/10.1088/0953-4075/35/4/330.

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26

Chiesa, Mario, Elio Giamello, Stefano Livraghi, Maria Cristina Paganini, Valeria Polliotto, and Enrico Salvadori. "Electron magnetic resonance in heterogeneous photocatalysis research." Journal of Physics: Condensed Matter 31, no. 44 (August 7, 2019): 444001. http://dx.doi.org/10.1088/1361-648x/ab32c6.

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27

Vink, Ivo T., Katja C. Nowack, Frank H. L. Koppens, Jeroen Danon, Yuli V. Nazarov, and Lieven M. K. Vandersypen. "Locking electron spins into magnetic resonance by electron–nuclear feedback." Nature Physics 5, no. 10 (August 16, 2009): 764–68. http://dx.doi.org/10.1038/nphys1366.

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28

Blinc, R., D. Arcon, P. Cevc, I. Pocsik, M. Koos, Z. Trontelj, and Z. Jaglicic. "nuclear magnetic resonance and electron spin resonance of amorphous hydrogenated carbon." Journal of Physics: Condensed Matter 10, no. 30 (August 3, 1998): 6813–24. http://dx.doi.org/10.1088/0953-8984/10/30/019.

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29

Pavesi, Laura, and Fabio Tedoldi. "Electron Paramagnetic Resonance and Proton Nuclear Magnetic Resonance Relaxations in Polyanilines." Polymers for Advanced Technologies 8, no. 1 (January 1997): 30–34. http://dx.doi.org/10.1002/(sici)1099-1581(199701)8:1<30::aid-pat610>3.0.co;2-n.

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30

Sorokina, Olga N., Alexander L. Kovarski, Marina A. Lagutina, Sergey A. Dubrovskii, and Fridrikh S. Dzheparov. "Magnetic Nanoparticles Aggregation in Magnetic Gel Studied by Electron Magnetic Resonance (EMR)." Applied Sciences 2, no. 2 (April 10, 2012): 342–50. http://dx.doi.org/10.3390/app2020342.

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31

Kadushkin, V. I. "Resonance modulation of electron-electron relaxation by a quantizing magnetic field." Semiconductors 39, no. 7 (July 2005): 826–29. http://dx.doi.org/10.1134/1.1992642.

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32

Morais, P. C., A. Alonso, O. Silva, and N. Buske. "Electron paramagnetic resonance of nitroxide-doped magnetic fluids." Journal of Magnetism and Magnetic Materials 252 (November 2002): 53–55. http://dx.doi.org/10.1016/s0304-8853(02)00611-x.

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33

de Biasi, R. S., and M. L. N. Grillo. "Electron magnetic resonance of gadolinium-doped calcium fluoride." Physica B: Condensed Matter 407, no. 12 (June 2012): 2164–68. http://dx.doi.org/10.1016/j.physb.2012.02.032.

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34

Cherkasov, F. G., I. V. Ovchinnikov, A. N. Turanov, S. G. L’vov, V. A. Goncharov, and A. Ya Vitols. "Electron paramagnetic resonance measurements of static magnetic susceptibility." Low Temperature Physics 23, no. 2 (February 1997): 174–76. http://dx.doi.org/10.1063/1.593350.

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35

Berliner, Lawrence J., and Xiaoming Wan. "In vivo pharmacokinetics by electron magnetic resonance spectroscopy." Magnetic Resonance in Medicine 9, no. 3 (March 1989): 430–34. http://dx.doi.org/10.1002/mrm.1910090317.

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36

Katsumata, Koichi. "High-frequency electron spin resonance in magnetic systems." Journal of Physics: Condensed Matter 12, no. 47 (November 6, 2000): R589—R614. http://dx.doi.org/10.1088/0953-8984/12/47/201.

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37

Park, Jong Min, Kyung Hwan Shin, Jung-in Kim, So-Yeon Park, Seung Hyuck Jeon, Noorie Choi, Jin Ho Kim, and Hong-Gyun Wu. "Air–electron stream interactions during magnetic resonance IGRT." Strahlentherapie und Onkologie 194, no. 1 (September 15, 2017): 50–59. http://dx.doi.org/10.1007/s00066-017-1212-z.

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38

Patel, J. M., S. P. Vaidya, and R. V. Mehta. "Electron spin resonance spectra of certain magnetic fluids." Journal of Magnetism and Magnetic Materials 65, no. 2-3 (March 1987): 273–75. http://dx.doi.org/10.1016/0304-8853(87)90049-7.

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39

Popov, I. Yu, and E. S. Tesovskaya. "Electron in a multilayered magnetic structure: resonance asymptotics." Theoretical and Mathematical Physics 146, no. 3 (March 2006): 361–72. http://dx.doi.org/10.1007/s11232-006-0045-1.

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40

Dubiel, Łukasz, Andrzej Wal, Ireneusz Stefaniuk, Antoni Żywczak, and Wojciech Maziarz. "Electron magnetic resonance study of the Ni47Co3Mn35.5In14.5 ribbons." Journal of Magnetism and Magnetic Materials 530 (July 2021): 167930. http://dx.doi.org/10.1016/j.jmmm.2021.167930.

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41

Rhodes, Christopher J. "Magnetic Resonance Spectroscopy." Science Progress 100, no. 3 (September 2017): 241–92. http://dx.doi.org/10.3184/003685017x14993478654307.

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Since the original observation by Zeeman, that spectral lines can be affected by magnetic fields, ‘magnetic spectroscopy’ has evolved into the broad arsenal of techniques known as ‘magnetic resonance’. This review focuses on nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR), and muon spin resonance (μSR): methods which have provided unparalleled insight into the structures, reactivity and dynamics of molecules, and thereby contributed to a detailed understanding of important aspects of chemistry, and the materials, biomedical, and environmental sciences. Magnetic resonance imaging (MRI), in vivo magnetic resonance spectroscopy (MRS) and functional magnetic resonance spectroscopy (fMRS) are also described. EPR is outlined as a principal method for investigating free radicals, along with biomedical applications, and mention is given to the more recent innovation of pulsed EPR techniques. In the final section of the article, the various methods known as μSR are collected under the heading ‘muon spin resonance’, in order to emphasise their complementarity with the more familiar NMR and EPR.

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42

Atsarkin, V. A., and V. V. Demidov. "Magnetic-field-controlled phase separation in manganites: Electron magnetic resonance study." Journal of Experimental and Theoretical Physics 103, no. 4 (October 2006): 589–96. http://dx.doi.org/10.1134/s1063776106100104.

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43

Fittipaldi, M., R. Mercatelli, S. Sottini, P. Ceci, E. Falvo, and D. Gatteschi. "Sensing the quantum behaviour of magnetic nanoparticles by electron magnetic resonance." Physical Chemistry Chemical Physics 18, no. 5 (2016): 3591–97. http://dx.doi.org/10.1039/c5cp07018j.

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44

Chmielewski, Piotr J., Lechoslaw Latos-Grazynski, and Ewa Pacholska. "Low-Valent Nickel Thiaporphyrins. Nuclear Magnetic Resonance and Electron Paramagnetic Resonance Studies." Inorganic Chemistry 33, no. 9 (April 1994): 1992–99. http://dx.doi.org/10.1021/ic00087a040.

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45

Danhier, Pierre, and Bernard Gallez. "Electron paramagnetic resonance: a powerful tool to support magnetic resonance imaging research." Contrast Media & Molecular Imaging 10, no. 4 (November 2, 2014): 266–81. http://dx.doi.org/10.1002/cmmi.1630.

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46

Bingham, Stephen J., Daniel Wolverson, and Andrew J. Thomson. "Coherent Raman detected electron spin resonance spectroscopy of metalloproteins: linking electron spin resonance and magnetic circular dichroism." Biochemical Society Transactions 36, no. 6 (November 19, 2008): 1187–90. http://dx.doi.org/10.1042/bst0361187.

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The simultaneous excitation of paramagnetic molecules with optical (laser) and microwave radiation in the presence of a magnetic field can cause an amplitude, or phase, modulation of the transmitted light at the microwave frequency. The detection of this modulation indicates the presence of coupled optical and ESR transitions. The phenomenon can be viewed as a coherent Raman effect or, in most cases, as a microwave frequency modulation of the magnetic circular dichroism by the precessing magnetization. By allowing the optical and magnetic properties of a transition metal ion centre to be correlated, it becomes possible to deconvolute the overlapping optical or ESR spectra of multiple centres in a protein or of multiple chemical forms of a particular centre. The same correlation capability also allows the relative orientation of the magnetic and optical anisotropies of each species to be measured, even when the species cannot be obtained in a crystalline form. Such measurements provide constraints on electronic structure calculations. The capabilities of the method are illustrated by data from the dimeric mixed-valence CuA centre of nitrous oxide reductase (N2OR) from Paracoccus pantotrophus.

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47

Komorowska, M., P. Sitarek, and J. Misiewicz. "Electron paramagnetic resonance in Zn3P2." Physica Status Solidi (a) 144, no. 1 (July 16, 1994): 189–93. http://dx.doi.org/10.1002/pssa.2211440121.

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48

Seleznyova, Kira, Mark Strugatsky, Sergey Yagupov, Yuliya Mogilenec, Alexey Drovosekov, Natalia Kreines, Patrick Rosa, and Janis Kliava. "Electron magnetic resonance of iron-gallium borate single crystals." Journal of Applied Physics 125, no. 22 (June 14, 2019): 223905. http://dx.doi.org/10.1063/1.5095753.

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49

Papanicolaou, N., A. Orendáčová, and M. Orendáč. "Electron-spin resonance in spin-1 planar magnetic chains." Physical Review B 56, no. 14 (October 1, 1997): 8786–98. http://dx.doi.org/10.1103/physrevb.56.8786.

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50

von Neumann-Cosel, P. "Giant magnetic quadrupole resonance studied with 180° electron scattering." Nuclear Physics A 649, no. 1-4 (March 1999): 77–84. http://dx.doi.org/10.1016/s0375-9474(99)00043-3.

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