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Journal articles on the topic 'Barrier of rotation'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

GANGAMANI, H. V., ACHALA L. NARGUND, and M. VENKATACHALAPPA. "An Analysis of Internal Gravity Wave Tunnelling in a Stratified Region Along with Rotation." JOURNAL OF ADVANCES IN PHYSICS 10, no. 2 (2015): 2741–52. http://dx.doi.org/10.24297/jap.v10i2.1332.

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The internal gravity wave tunnelling in presence of earthâ€™s rotation is studiedfor different density barriers. An exponential approximation used revealsthe existence of evanescence in the barrier region which signifies the trappingof wave energy in the tunnelling region. The Transmission coefficients arecomputed for different density barriers and the comparative study shows thatacross the locally mixed region the transmission is enhanced. The asymptoticanalysis of the transmission co-efficient using the rotational parameter revealsthe convergence and the graphs shows that the transmission de

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2

Radchenko, Pavel A., Andrey V. Radchenko, and Stanislav P. Batuev. "A numerical study of the high-velocity interaction of rotating strikers having different head shapes with a barrier of finite thickness." Vestnik Tomskogo gosudarstvennogo universiteta. Matematika i mekhanika, no. 87 (2024): 120–34. http://dx.doi.org/10.17223/19988621/87/10.

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Numerical simulation methods are used to study the effect of rotation of cylindrical strikers made of high-strength steel on the high-velocity interaction with a steel barrier. Three types of striker head shapes are considered: ogival, hemispherical, and flat. The initial velocity of the striker is 1000 m/s, and the rotation frequency varies from 0 to 10000 revolutions per second. The striker-barrier interaction angle varies from 0° to 75°. The modeling is carried out in a three-dimensional formulation using the author’s EFES 2.0 software package. This allows the simulation of the fragmentatio

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3

LI, GUOPING, WEIREN XU, CHAOJUN ZHANG, JIANWU WANG, and CHENGBU LIU. "THEORETICAL STUDY ON THE INTERNAL ROTATION OF NITROTYL OF BENZALDOXIMES." Journal of Theoretical and Computational Chemistry 05, no. 01 (2006): 111–20. http://dx.doi.org/10.1142/s0219633606002088.

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The internal rotations of nitrotyl around the bond C–C in Z- and E-benzaldoximes and their various substituted species have been investigated theoretically by the method of density functional theory (DFT) at the B3LYP/6-31G* level. The corresponding rotation transition states have been optimized. The potential barriers and the rates of the internal rotations of various species have been calculated. The rotation barrier of Z-benzaldoxime is lower than that of E-isomer. The para-substitution has only a small influence on the rotation barriers. The conjugations are consolidated in the acidic and

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4

Brownstein, S., and J. Roovers. "Calculation of barriers to rotation in PEEK and some of its substituted derivatives." Canadian Journal of Chemistry 75, no. 9 (1997): 1225–28. http://dx.doi.org/10.1139/v97-147.

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Barriers to rotation have been calculated by molecular mechanics, using the force field MM+, for a fragment of PEEK and its methyl, ethyl, isopropyl, tert-butyl and di-tert-butyl, substituted derivatives. The barrier for the nearer C—O bond increases from 2.0 kcal/mol in KEEK to 16 kcal/mol in dibutyl substituted KEEK as the bulkiness of the substituent increases. The rotation barrier of the further C—O bond is not affected by the substituent. Keywords: rotation barriers, PEEK, molecular mechanics.

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5

Craik, DJ, PR Andrews, C. Border, and SLA Munro. "Conformational Studies of Thyroid Hormones. I. The Diphenyl Ether Moiety." Australian Journal of Chemistry 43, no. 5 (1990): 923. http://dx.doi.org/10.1071/ch9900923.

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Conformational flexibility round the diphenyl ether linkage in the thyroid hormones has been investigated by means of molecular orbital (AM1) and classical potential-energy calculations. The results obtained from these theoretical approaches are in qualitative agreement with those from n.m.r. spectroscopy, i.e., the barrier to rotation around this structural feature is sufficiently low to allow rapid interconversion between two stable conformers to occur at room temperature. Two pathways of rotation around the diphenyl ether bridge were explored and were both calculated to be approximately 14-

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6

Nair, K. P. Rajappan, Sven Herbers, Daniel A. Obenchain, and Jens-Uwe Grabow. "Internal methyl rotation and molecular structure of trifluorotoluenes: microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluene." Canadian Journal of Physics 98, no. 6 (2020): 543–50. http://dx.doi.org/10.1139/cjp-2019-0477.

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The microwave rotational spectra of 2,3,4- and 2,4,5-trifluorotoluenes, along with all 13C isotopic species in natural abundance, have been recorded in the frequency range 8–27 GHz employing pulsed-jet Fourier transform microwave spectroscopy. The analysis of the spectra in the lowest torsional state has yielded the rotational constants, centrifugal distortion constants, three-fold barrier to methyl rotation, and the direction of the internal rotation axis in the moment of inertia principal axes systems of these trifluorotoluenes. For both molecules, the molecular constants of their eight isot

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7

Baerends, Evert Jan, F. Matthias Bickelhaupt, and Peter Schreiner. "The rotation barrier in ethane." Nachrichten aus der Chemie 52, no. 5 (2004): 581. http://dx.doi.org/10.1002/nadc.20040520519.

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8

Khemissi, Safa, Lynn Ferres, and Ha Vinh Lam Nguyen. "Two Coupled Low-Barrier Large Amplitude Motions in 3,5-Dimethylanisole Studied by Microwave Spectroscopy." Molecules 30, no. 6 (2025): 1195. https://doi.org/10.3390/molecules30061195.

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The microwave spectrum of 3,5-dimethylanisole was recorded using a pulsed molecular jet Fourier transform microwave spectrometer, covering the frequency range from 2.0 to 26.5 GHz. Splittings from internal rotations of the syn-m and anti-m-methyl groups were observed, analyzed, and modeled using the XIAM and the ntop programs for a data set including 622 rotational lines. The torsional barriers of the syn-m and anti-m-methyl groups were determined to be 58.62367(53) cm−1 and 36.28449(69) cm−1, respectively. The low barriers to internal rotation of both methyl groups posed significant challenge

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9

Randeil, Jeremy, A. Peter Cox, and H. Dreizier. "Gauche Propanal: Microwave Spectrum and Methyl Barrier." Zeitschrift für Naturforschung A 42, no. 9 (1987): 957–62. http://dx.doi.org/10.1515/zna-1987-0908.

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The barrier hindering internal rotation of the methyl group was determined by analysing ground-state A, E splittings of rotational lines in the 0+ and 0- torsional states of gauche propanal. The value V3 = 886 (10)cm-1 obtained can be compared with that obtained earlier for the cis rotamer.The A rotational constant has also been determined, its value averaged over the two lowest states being 26248.41 (5) MHz.

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10

ALONSO, JOSE, ALBERTO LESARRI, JUAN LOPEZ, SUSANA BLANCO, ISABELLE KLEINER, and JEAN DEMAISON. "Rotational spectrum, internal rotation barrier and structure of 3,3,3-trifluoropropene." Molecular Physics 91, no. 4 (1997): 731–50. http://dx.doi.org/10.1080/00268979709482763.

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11

Ernst, Ludger, Thomas Rieck, and Mark Soliven. "Article." Canadian Journal of Chemistry 77, no. 11 (1999): 1697–706. http://dx.doi.org/10.1139/v99-130.

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Schaefer's "J method" was employed to show that 2-cyclopropyl-1,3-dimethylbenzene (5) in solution prefers the perpendicular conformation in which the torsional angle Θ between the C(1)-H bond of the cyclopropyl group and the plane of the benzene ring is 90°. This is opposed to the situation in cyclopropylbenzene (3) where the bisected conformer (Θ = 0°) prevails. From the value of -0.85 ± 0.01 Hz for 6J(H-alpha,H-para) in 5 (for solutions in CS2 and in acetone) a barrier to rotation about the cyclopropyl-aryl bond of 6.4 kJ/mol can be derived if a predominantly two-fold potential and a vanishi

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12

Grunenberg, Jörg. "The rotation barrier in ethane III." Nachrichten aus der Chemie 52, no. 7-8 (2004): 831. http://dx.doi.org/10.1002/nadc.20040520725.

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13

Bestmann, G., and H. Dreizler. "A Redetermination of the Barrier to Internal Rotation of 2-Fluoropropene." Zeitschrift für Naturforschung A 40, no. 3 (1985): 267–70. http://dx.doi.org/10.1515/zna-1985-0310.

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We present the determination of the methyl barrier to internal rotation from the rotational spectrum in the ground state of 2-fluoropropene. A complete set of barrier parameters could be determined. The results are compared with those of 2-chloro- and 2-bromopropene, achieved by the same technique and evaluation method.

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14

Sigalov, Mark, Vladimir Lokshin, Nina Larina, and Vladimir Khodorkovsky. "Hindered rotational barriers in conjugated donor–acceptor substituted systems: calculations vs. experiments." Physical Chemistry Chemical Physics 22, no. 3 (2020): 1214–21. http://dx.doi.org/10.1039/c9cp06234c.

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15

Huang, Wenyuan, Javix Thomas, Wolfgang Jäger, and Yunjie Xu. "Tunnelling and barrier-less motions in the 2-fluoroethanol–water complex: a rotational spectroscopic and ab initio study." Physical Chemistry Chemical Physics 19, no. 19 (2017): 12221–28. http://dx.doi.org/10.1039/c7cp01666b.

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16

Bestmann, G., W. Lalowski, and H. Dreizler. "Determination of a High Barrier Hindering Internal Rotation from the Ground State Spectrum. The Methylbarrier of Propane." Zeitschrift für Naturforschung A 40, no. 3 (1985): 271–73. http://dx.doi.org/10.1515/zna-1985-0311.

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The internal rotation barrier V3, the moment of inertia Iα of the methyl tops and the angle between the two internal rotation axes were determined from the torsional fine structure of the rotational spectrum in the torsional ground state. A tilt angle of 1.4° of the methyl groups toward each other results.

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17

Jaman, A. I., P. Hemant Kumar, and P. R. Bangal. "Millimeter-Wave Rotational Spectrum, Barrier to Internal Rotation, and DFT Calculation of o-Tolunitrile." Journal of Atomic, Molecular, and Optical Physics 2011 (July 26, 2011): 1–8. http://dx.doi.org/10.1155/2011/480396.

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The millimeter-wave rotational spectra of o-tolunitrile (C6H4CH3CN) have been investigated in the ground torsional state in the frequency range 50.0–75.0 GHz. Many high-J rotational lines with large A-E splitting due to internal rotation of the methyl top have been assigned. A least squares analysis of the A-E splitting of 92 transitions resulted in the determination of accurate values of internal rotation parameters. The observed parameters were compared with the previously reported experimental values and DFT calculation results.

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18

Yousuf, Salman J., Nguyen S. Nguyen, Monika Farhangi Oskuei, John Kwagyan, and Leslie S. Jones. "Virtual Ophthalmology Rotation for Visiting Medical Students: An Opportunity to Enhance Diversity in the Workforce." Journal of Academic Ophthalmology 15, no. 01 (2023): e51-e55. http://dx.doi.org/10.1055/s-0043-1760831.

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Abstract Introduction We created a virtual rotation to facilitate the exposure of ophthalmology to medical students and serve as a pilot program to help attract students from under-represented in medicine (URM) backgrounds. In addition to the rotation eliminating the financial burdens associated with in-person away rotations, we offered a not-for-credit (i.e., drop-in) option that included sessions outside the typical clinic hours. This option reduced scheduling conflicts as a barrier to enrollment and allowed junior medical students and postgraduates to participate and hopefully further devel

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19

Ševeček, P., M. Brož, and M. Jutzi. "Impacts into rotating targets: angular momentum draining and efficient formation of synthetic families." Astronomy & Astrophysics 629 (September 2019): A122. http://dx.doi.org/10.1051/0004-6361/201935690.

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About 10% of the observed asteroids have rotational periods lower than P = 3 h and seem to be relatively close to the spin barrier. Yet, the rotation has often been neglected in simulations of asteroid collisions. To determine the effect of rotation, we performed a large number of impact simulations with rotating targets. We developed a new unified smoothed particle hydrodynamics and N-body code with self-gravity, suitable for simulations of both fragmentation phase and gravitational reaccumulation. The code has been verified against previous ones, but we also tested new features, such as rota

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20

Hinze, R., A. Lesarri, J. C. López, J. L. Alonso, and A. Guarnieri. "Rotational spectrum, internal rotation barrier andabinitiocalculations on 1‐chloro‐1‐fluoroethane." Journal of Chemical Physics 104, no. 24 (1996): 9729–34. http://dx.doi.org/10.1063/1.471734.

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21

Alonso, José L., Juan C. López, Susana Blanco, and Antonio Guarnieri. "Rotational Spectrum and Internal Rotation Barrier of 1-Chloro-1,1-difluoroethane." Journal of Molecular Spectroscopy 182, no. 1 (1997): 148–62. http://dx.doi.org/10.1006/jmsp.1996.7214.

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22

Dreizler, H., and N. Hansen. "High Resolution Microwave Spectroscopy of Ethyl Vinyl Ether: Accurate Determination of the Methyl Top Internal Rotation Barrier." Zeitschrift für Naturforschung A 55, no. 5 (2000): 481–85. http://dx.doi.org/10.1515/zna-2000-0501.

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Abstract We have performed an investigation of the internal rotation of the methyl group in trans-cis ethyl vinyl ether by using molecular beam-Fourier transform Microwave (MB-FTMW) spectroscopy. Rotational spectra (up to J = 20) were recorded in the frequency region 4-19 GHz. Due to the internal rotation of the methyl group, some rotational transitions were split and the torsional barrier could be determined to V3 (CH3) = 1074.4(4) cm-1 .

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23

Yi, Xianzhou. "Three DOF Rotation Compensation in Floating HFSWR for Ocean Current Inversion." Journal of Physics: Conference Series 2718, no. 1 (2024): 012017. http://dx.doi.org/10.1088/1742-6596/2718/1/012017.

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Abstract High-frequency surface wave radar (HFSWR) has been widely used for ocean surface current inversion. Floating this radar can realize the ocean surface inversion among large areas far away from the coastline. However, six degree-of-freedom (DOF) movements will set the barrier for the ocean current inversion on its radial velocity estimation and direction of arrival estimation. Among these movements, three DOF rotations can cause both Doppler modulation and azimuth modulation while three DOF translations only cause Doppler modulation which is dependent on the arrival direction of echoes.

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24

Gottlieb, Hugo E., Samuel Braverman, and Shlomo Levinger. "Rotation barrier in a doubly vinylogous amide." Journal of Organic Chemistry 55, no. 11 (1990): 3655–58. http://dx.doi.org/10.1021/jo00298a051.

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25

Grein, F. "Barrier to internal rotation in hydrogen persulfide." Chemical Physics Letters 116, no. 4 (1985): 323–25. http://dx.doi.org/10.1016/0009-2614(85)80177-9.

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26

Voges, K., J. Gripp, H. Hartwig, and H. Dreizler. "Analysis of Torsion in a Three-Top Molecule. Torsional Barrier and Moment of Inertia of Trimethyl Ethynyl Germane." Zeitschrift für Naturforschung A 51, no. 4 (1996): 299–305. http://dx.doi.org/10.1515/zna-1996-0409.

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Internal rotation effects for a large number of molecules containing one or two symmetric internal rotors have been investigated using microwave spectroscopy. The high resolution of molecular beam Fourier transform microwave spectroscopy revealed now the internal rotation fine structure in the rotational spectrum of trimethyl ethynyl germane, (CH3)3GeC=CH. After assigning the rotational transition J = 1 → 0 in the vibrational and torsional ground state to the symmetry species of the molecular symmetry group G162 , the torsional barrier V3 and the rotational constant B0 could be determined to (

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27

Schaefer, Ted, Craig S. Takeuchi, Guy M. Bernard, and Frank E. Hruska. "Theoretical and experimental barriers to internal rotation in 2,6-difluorobenzaldehyde and 2,4,6-trifluorobenzaldehyde. Relatively low barriers." Canadian Journal of Chemistry 73, no. 1 (1995): 106–12. http://dx.doi.org/10.1139/v95-016.

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The free energies of activation at 110 K for rotation about the exocyclic C—C bonds in 2,6-difluorobenzaldehyde and 2,4,6-trifluorobenzaldehyde, in dimethyl ether solutions, are 18.8 ± 0.5 and 20.0 ± 0.5 kJ mol−1, respectively, as determined from 19F{1H} dynamic nuclear magnetic resonance measurements. For the parent compound ΔG≠ is 32.2 kJ mol−1 in the same solvent. These free energy barriers, the lowest available for benzaldehyde derivatives, are likely a result of steric and electrostatic repulsions between the C+—O− and C+—F− bonds. Computations of the spectroscopic barrier in the 2,6-difl

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28

Wen, Jin, Meifang Zhu, and Leticia González. "Solvation Effects on the Thermal Helix Inversion of Molecular Motors from QM/MM Calculations." Chemistry 4, no. 1 (2022): 185–95. http://dx.doi.org/10.3390/chemistry4010016.

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Molecular motors convert light and thermal energies into mechanical work, offering good opportunities to design novel molecular devices. Among them, molecular motors alternate a photoisomerization and a thermal helix inversion to achieve unidirectional rotation. The rotational speed is limited by the helix inversion step, which in turn is governed by a barrier in the electronic ground state. In this work, we systematically study the solvation effect on the thermal process of selected molecular motors, comparing reaction barriers obtained from both density functional theory (DFT) in the isolate

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29

Vormann, Kirsten, Helmut Dreizler, Hans Hübner, and Wolfgang Hüttner. "Methyl Internal Rotation Fine Structure in the Ground State Rotational Spectrum of Gauche Butane." Zeitschrift für Naturforschung A 45, no. 8 (1990): 989–94. http://dx.doi.org/10.1515/zna-1990-0808.

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Abstract The methyl torsional fine structure in the rotational spectrum of gauche butane in the vibrational ground state was investigated in the frequency range between 10 and 141 GHz. Using the internal axis method (IAM) in the formulation of Woods, all internal rotation parameters were determined with high accuracy. The barrier height of the methyl internal rotation was determined to 11.34 (29) kJ/mol (2.710 (69) kcal/mol)

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30

Osei-Twum, Emmanuel Yaw. "Proton nuclear magnetic resonance studies of nucleosides: hindered internal rotation in N-dimethylaminomethylene derivatives of adenosine, guanosine, and cytidine." Canadian Journal of Chemistry 71, no. 7 (1993): 1006–9. http://dx.doi.org/10.1139/v93-134.

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Studies of the internal rotation about the C—N bond of the dimethylaminomethylene (DMAM) group of DMAM-adenosine, 1, DMAM-guanosine, 2, and DMAM-cytidine, 3, was determined by high-resolution 1H NMR spectroscopy. Arrhenius plots (ln k = ln A − Ea/RT) were used to determine the barriers to internal rotation, Ea, of the compounds. They were found to be 58.0 ± 2.4 kJ mol−1, 71.2 ± 1.4 kJ mol−1, and 62.8 ± 2.4 kJ mol−1 for 1, 2, and 3, respectively. At the same time the coalescence temperatures, tc, for the compounds were determined and found to be 93.5 °C for 1, 124.7 °C for 2, and 119.6 °C for 3

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31

Schaefer, Ted, Christian Beaulieu, and Rudy Sebastian. "2-Phenyladamantane as a model for axial phenylcyclohexane. 1H NMR and molecular orbital studies of motion about the Csp2—Csp3 bond." Canadian Journal of Chemistry 69, no. 3 (1991): 503–8. http://dx.doi.org/10.1139/v91-075.

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The 1H NMR spectra of the aromatic groups of 2-phenylcyclohexane and 2-phenyladamantane, in CS2/C6D12 solution at 300 K, are analyzed to yield the long-range coupling constants between the α and ring protons. The coupling over six bonds is related to the internal rotational potential about the Csp2—Csp3 bond in these molecules. It is confirmed that the equatorial isomer of phenylcyclohexane has the parallel conformer, that in which the aromatic plane lies in the symmetry plane bisecting the cyclohexane moiety, as the most stable. The apparent twofold barrier to rotation about the exocyclic car

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32

Halimehjani, Azim Ziyaei, Martin Dračínský, and Petr Beier. "One-pot three-component route for the synthesis of S-trifluoromethyl dithiocarbamates using Togni’s reagent." Beilstein Journal of Organic Chemistry 13 (November 24, 2017): 2502–8. http://dx.doi.org/10.3762/bjoc.13.247.

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A one-pot three-component route for the synthesis of S-trifluoromethyl dithiocarbamates by the reaction of secondary amines, carbon disulfide and Togni’s reagent is described. The reactions proceed in moderate to good yields. A similar reaction using a primary aliphatic amine afforded the corresponding isothiocyanate in high yield. A variable temperature NMR study revealed a rotational barrier of 14.6, 18.8, and 15.9 kcal/mol for the C–N bond in the dithiocarbamate moiety of piperidine, pyrrolidine, and diethylamine adducts, respectively. In addition, the calculated barriers of rotation are in

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33

Fraser, G. T., D. D. Nelson, G. J. Gerfen, and W. Klemperer. "The rotational spectrum, barrier to internal rotation, and structure of NH3–N2O." Journal of Chemical Physics 83, no. 11 (1985): 5442–49. http://dx.doi.org/10.1063/1.449714.

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34

Sadvakassova, Madina Zh, Andrei I. Khlebnikov, Abdigali A. Bakibaev, et al. "Rotational Barriers in N-Benzhydrylformamides: An NMR and DFT Study." Molecules 28, no. 2 (2023): 535. http://dx.doi.org/10.3390/molecules28020535.

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N-Benzhydrylformamides are pharmacologically active compounds with anticonvulsant, enzyme-inducing, antihypoxic, and other types of biological activity. The conformational behavior of benzhydrylformamides is determined to a great extent by the presence of substituents at the nitrogen atom and in the ortho-position(s) of the diphenylmethane moiety. Particularly, the NMR spectra of these compounds often contain two sets of signals originating from different orientations of the formyl group. With the use of the dynamic NMR method and DFT calculations, we investigated the internal rotations of aro

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35

Lu, Wenxin, Tiantian Mu, Yuehong Zhang, et al. "A Photocontrolled Molecular Rotor Based on Azobenzene-Strapped Mixed (Phthalocyaninato)(Porphyrinato) Rare Earth Triple-Decker." Molecules 30, no. 2 (2025): 326. https://doi.org/10.3390/molecules30020326.

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Effectively regulating the rotary motions of molecular rotors through external stimuli poses a tremendous challenge. Herein, a new type of molecular rotor based on azobenzene-strapped mixed (phthalocyaninato)(porphyrinato) rare earth triple-decker complex Azo-1 is reported. Electronic absorption and 1H NMR spectra manifested the reversible isomerization of the rotor Azo-1 between the trans configuration and the cis configuration. The rotational behavior of phthalocyanine rotator in two configurations were investigated by VT-1H NMR experiments, and the results indicated that the phthalocyanine

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36

Okuyama, Katsuhiko, Naohiko Mikami, and Mitsuo Ito. "Internal Rotation of the Methyl Group in the Electronically Excited State: o- and m-Toluidine." Laser Chemistry 7, no. 2-4 (1987): 197–212. http://dx.doi.org/10.1155/lc.7.197.

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The fluorescence excitation and dispersed fluorescence spectra of jet-cooled o- and m-toluidine were observed. Vibrational analysis of the spectra provided us with the potentials for the internal rotation of the CH3 group in both ground and excited states. In o-toluidine, a large potential barrier to the internal rotation in the ground state is practically removed in the excited state. On the other hand, a nearly free internal rotation of the CH3 group in the ground state of m-toluidine gains a large barrier by the electronic excitation. The great change in the barrier height upon the electron

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37

Penner, Glenn H., Baiyi Zhao, and Kenneth R. Jeffrey. "Molecular Dynamics in the Solid Trimethylamine-Borane Complex: A Deuterium NMR Study." Zeitschrift für Naturforschung A 50, no. 1 (1995): 81–89. http://dx.doi.org/10.1515/zna-1995-0111.

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Abstract The molecular dynamics of solid (CH3)3NBH3 is investigated by deuterium NMR spectroscopy. Variable temperature lineshape analyses yield activation energies of 27 ± 3, 19 ± 2, and 12.5 ± 2 kJ/mol for -CH3, -N(CH3)3 and -BH3 rotation, respectively. Analysis of the temperature depen dence of the spin-lattice relaxation times, T1 , gives activation energies of 33 ± 3, 15 ± 1.5, and 14 ± 1.5 kJ/mol, respectively. Direct comparison of rotational exchange rates (from lineshape simu lations) an of rotational correlation times (from T1 analyses) for -N(CH3)3 and -BH3 rotation indicate that t

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38

CUI, YA SONG, LI JIAO ZHAO, YONG DONG LIU, and RU GANG ZHONG. "THEORETICAL STUDY ON INTERNAL ROTATION OF NITROSOUREAS AND TOXICOLOGICAL ANALYSIS." Journal of Theoretical and Computational Chemistry 06, no. 02 (2007): 245–53. http://dx.doi.org/10.1142/s0219633607003064.

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A theoretical study has been carried out for internal rotation of nitrosoureas at the B3LYP/6-311G* level of theory. For each nitrosourea compound, two ground state structures have been found and the E isomer is predicted to be more stable than the Z isomer. Two transition state conformations for the isomerization have also been obtained and the calculated results show that the isomerization through TS1 is easier than that through TS2. The relationship between energy barrier and toxicity has also been investigated. It is concluded that the carcinogenic potency increases along with the decrease

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39

Law, Harvey, Jenny Law, and Marek Kierzkowski. "Absorptive noise barrier development." Journal of the Acoustical Society of America 154, no. 4_supplement (2023): A351. http://dx.doi.org/10.1121/10.0023767.

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This paper reveals the development of an absorptive, self-supporting noise barrier panel for external applications. Designed for use as a temporary external noise barrier for construction sites and roadside noise barriers. The absorptive noise barrier panel is a module base design that is easy to assemble, disassemble, and re-deploy. The barrier panel utilizes recycled plastic materials, such as milk bottles and other soft plastics, making it one of the most environmentally friendly products. The barrier is manufactured in one process via a unique rotation molding method. It is weather resista

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40

Wilson, Chick C. "Barrier heights to methyl group rotation in dimethylnaphthalenes." Chemical Physics Letters 362, no. 3-4 (2002): 249–54. http://dx.doi.org/10.1016/s0009-2614(02)00960-0.

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Grossi, Loris, та Giuseppe Placucci. "Benzoyl σ-radicals: the barrier to internal rotation". J. Chem. Soc., Chem. Commun., № 14 (1985): 943–44. http://dx.doi.org/10.1039/c39850000943.

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Deetz, Martin J., Christopher C. Forbes, Marco Jonas, Jeremiah P. Malerich, Bradley D. Smith, and Olaf Wiest. "Unusually Low Barrier to Carbamate C−N Rotation." Journal of Organic Chemistry 67, no. 11 (2002): 3949–52. http://dx.doi.org/10.1021/jo025554u.

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Chen, P. C. "Internal rotation study of some sixfold barrier molecules." International Journal of Quantum Chemistry 62, no. 2 (1997): 213–21. http://dx.doi.org/10.1002/(sici)1097-461x(1997)62:2<213::aid-qua9>3.0.co;2-z.

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Đorđević Zlatković, Miljana R., Niko S. Radulović, Miroslav Dangalov, and Nikolay G. Vassilev. "Conformation Analysis and Stereodynamics of Symmetrically ortho-Disubstituted Carvacrol Derivatives." Molecules 29, no. 9 (2024): 1962. http://dx.doi.org/10.3390/molecules29091962.

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The design and synthesis of analogs of natural products can be a valuable source of medicinal preparations for the pharmaceutical industry. In the present study, the structural elucidation of eleven derivatives of 2,4-dihalogeno substituted synthetic analogues of the natural compound carvacrol was carried out by means of NMR experiments, and of another thirteen by DFT calculations. By selective NOE experiments and the irradiation of CH signals of the isopropyl group, individual conformers were assigned as syn and anti. By comparing GIAO/B3LYP/6-311++G(d,p)-calculated and experimentally measure

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Rottstegge, J., H. Hartwig, and H. Dreizler. "The rotational spectrum, structure and barrier V6 to internal rotation of p-fluorotoluene." Journal of Molecular Structure 478, no. 1-3 (1999): 37–47. http://dx.doi.org/10.1016/s0022-2860(98)00656-5.

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Obenchain, Daniel A., Pablo Pinacho, Sabrina Zinn, and Melanie Schnell. "The low-barrier methyl internal rotation in the rotational spectrum of 3-methylphenylacetylene." Journal of Molecular Structure 1213 (August 2020): 128109. http://dx.doi.org/10.1016/j.molstruc.2020.128109.

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Stavretis, Shelby E., Eugene Mamontov, Duncan H. Moseley, et al. "Effect of magnetic fields on the methyl rotation in a paramagnetic cobalt(ii) complex. Quasielastic neutron scattering studies." Physical Chemistry Chemical Physics 20, no. 32 (2018): 21119–26. http://dx.doi.org/10.1039/c8cp01660g.

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Thomsen, C., and H. Dreizler. "The Microwave Spectra of m-Xylene and m-Xylene-d10. Determination of the Low Methyl Internal Rotation Barrier." Zeitschrift für Naturforschung A 56, no. 9-10 (2001): 635–40. http://dx.doi.org/10.1515/zna-2001-0905.

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Abstract The rotational spectra of m-xylene, (CH3)2C6H4 and of m-xylene-d10, (CD3)2C6D4 have been recorded between 6 and 26.5 GHz using pulsed beam Fourier transform microwave spectroscopy. The clue for the assignment of the internal rotation multiplets was the inertial defect derived from the A1A1 species transitions. The rotational constants for m-xylene and m-xylene-d10 are A = 3572.1117(1) MHz / 2896.1195(17) MHz, B = 1761.8621(1) MHz / 1446.0236(15) MHz, C =1197.3943(2) MHz / 988.2357(7) MHz, the barrier to internal rotation of the two methyl groups are V3 = 53.7(16) J/mol / 39.8(5) J/mol

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Irasari, P., and P. Widiyanto. "Stator flux barriers to improving interior permanent magnet motor characteristics." IOP Conference Series: Earth and Environmental Science 927, no. 1 (2021): 012040. http://dx.doi.org/10.1088/1755-1315/927/1/012040.

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Abstract There are many methods to improve the characteristics of permanent magnet motors. One of them is by making flux barriers on the stator or rotor, or both. This paper discusses the adding stator flux barriers on the rectangular-shaped stator of the interior permanent magnet motor. The purpose is to increase the maximum rotation of the machine. The shape of the flux barrier is circular considering the ease of the manufacturing process, with the proposed diameter is one slot pitch. Several diameters of larger and smaller sizes will also be simulated for comparison. Other parameters, which

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Baweja, Shefali, Eleonore Antonelli, Safia Hussain, et al. "Revealing Internal Rotation and 14N Nuclear Quadrupole Coupling in the Atmospheric Pollutant 4-Methyl-2-nitrophenol: Interplay of Microwave Spectroscopy and Quantum Chemical Calculations." Molecules 28, no. 5 (2023): 2153. http://dx.doi.org/10.3390/molecules28052153.

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The structure and interactions of oxygenated aromatic molecules are of atmospheric interest due to their toxicity and as precursors of aerosols. Here, we present the analysis of 4-methyl-2-nitrophenol (4MNP) using chirped pulse and Fabry–Pérot Fourier transform microwave spectroscopy in combination with quantum chemical calculations. The rotational, centrifugal distortion, and 14N nuclear quadrupole coupling constants of the lowest-energy conformer of 4MNP were determined as well as the barrier to methyl internal rotation. The latter has a value of 106.4456(8) cm−1, significantly larger than t

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