Molecular polarisability. Quinoxaline and some of its derivatives

Hurley, J.D.; Fèvre, R. J. W. Le

doi:10.1039/j29670000824

Cited by 11 publications

(9 citation statements)

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“…Figure shows the (d f /d E )/ E 2 distribution obtained in comparison with the data of Tixier et al A good agreement between our extrapolated and the Tixier et al data for energy values above 0.79 E h can be observed. The numerical integration of our (d f /d E )/ E 2 over the entire energy range gives a value of 61.3 au for the static dipole polarizability of pyridine, in quite good agreement with previous values of 61.95 au and 64.11 au obtained from electric double-refraction measurements, whereas Tixier et al reported the value of 60.93 au obtained with a procedure similar to that of the present work.…”

Section: Resultssupporting

confidence: 91%

Photoabsorption and Photoionization Cross Sections of Pyridine in the Vacuum-Ultraviolet Energy Range

et al. 2019

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We have performed an experimental investigation into the interaction of vacuum-ultraviolet synchrotron radiation with pyridine molecules in the gas phase. Specifically, a double-ion chamber spectrometer was used to measure the absolute photoabsorption cross sections and the photoionization quantum yields from the ionization threshold to 21.5 eV. Moreover, photoionization and neutral-decay cross sections in absolute scale were derived from these data. In addition, the fragmentation pattern was investigated as a function of the photon energy by using a time-of-flight mass spectrometer and the photoelectron-photoion coincidence technique. Thus, the absolute partial ionization cross sections for each ionic fragment were obtained. Comparisons are made with experimental data available in the literature.

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Section: Resultssupporting

confidence: 91%

Photoabsorption and Photoionization Cross Sections of Pyridine in the Vacuum-Ultraviolet Energy Range

et al. 2019

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“…1. The dihedral angles that the phenyl groups make with the planar quinoxaline moiety in the title compound [46.7 (8) and 38.0 (9) ° ] agree with those observed previously for 2,3-diphenylquinoxaline in a benzene solution (ca 39°; Hurley & Le Fevre, 1967). A greater difference in these angles [22.1 (1) and 48.1 (1) °] has been reported for the crystal structure of 6,7-dimethyl-2,3-diphenylquinoxalinc (Wo~niak, Krygowski & Filipek, 1991).…”

Section: Commentsupporting

confidence: 79%

Diethyl 2-(2,3-diphenylquinoxalin-6-ylaminomethylene)malonate

Lokaj¹,

Kettmann²,

Vrábel³

et al. 1994

Acta Crystallogr C

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The substituted aminoethylenic group in the title compound, C28H25N304, is approximately coplanar with the heterocyclic plane [dihedral angle 16 (2) °] and the a-C atom C(23), is disordered between two well defined sites. This disorder originates from a flipping of the aminoethylenic moiety around the © 1994 International Union of Crystallography Printed in Great Britain -all fights reservedActa Crystallographica Section C ISSN 0108-2701 ©1994 LOKAJ, KETI'MANN, VRA, BEL, ILAVSK~" AND MILATA 1785 C(6)---N(5) bond. The phenyl rings at C(2) and C(3) are twisted out of the plane of the quinoxaline ring system by 46.7 (8) and 38.0 (9) ° , respectively. CommentThe overall conformation of the title molecule (I) and the numbering scheme are shown in Fig. 1. The dihedral angles that the phenyl groups make with the planar quinoxaline moiety in the title compound [46.7 (8) Fig. 1. Perspective drawing of the title compound and atomnumbering scheme. Displacement ellipsoids are drawn at the 40% probability level. Only one of the two disordered sites for C(23) is shown.As a consequence of the disorder of the methylenic atom C(23), the N(5)--C(231) and N(5)---C(232) bond lengths are very short, while the C(231)--C(24) and C(232)---C(24) distances are unusually long (Table 2). Other bond distances and angles in those parts of the molecule not affected by the disorder are quite normal.The substituted aminoethylenic moiety is approximately planar with the relevant torsion angles around the N(5)--C(23) bond being C(6)--N(5)--C(231)---C(24) = -179.2 (6) and C(6)--N(5)--C(232)--C(24) = -179.3 (9) °. Although a fast rotation around the C(6)---NH bond in several related compounds has been reported to occur in solution (Goljer, Milata & Ilavsk~,, 1989), the occurence of the two conformations of the aminoethylenic group has not yet been observed in the solid state. Experimental Crystal data118.5 (6) C (8) There is a twofold disorder at the C(23) atom and occupancy factors were fixed at 0.50 for both sites, C(231) and C(232), based on relative heights in a difference Fourier map. Positions of the H atoms, except those attached to the disordered C atom and its neighbouring N atom, were calculated and included in the Fc calculation with Biso set at 0.5/~2 higher than the Beq value of the parent C atom. The structure was solved using MULTAN80 (Main, Fiske, Hull, Lessinger, Germain, Declercq & Woolfson, 1980). All remaining calculations were performed with a local version of the NRC program system (Ahmed & Singh, 1973 AbstractThe title compound [N,N'-bis(benzoylphenyl)methanediamine, C27H22N202] was prepared by condensation of 4-aminobenzophenone (ABP) and formaldehyde at room temperature. In the molecule, two ABP moieties are linked by a methylene group. The bond lengths and angles within the two ABP groups are very similar; however, the dihedral angles between the sets of ring planes are quite different [83.1 (5) and 57.5 (3)°]. CommentRecently, crystals of 4-aminobenzophenone (ABP) were discovered to be a new and highly e...

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“…This conclusion is important, since experiences in electric property calculations of small molecules [12, 28 -32] have shown that reliable indications of the convergence of the HF results to the respective HF limits are slower, i.e., it is necessary to use larger basis sets to obtain it. Thus, from here on, the ADZP results will be used to compare with a selection of theoretical [17] and experimental [4,[21][22][23] , ␣ , and ⌬␣ values reported in the literature. For adenine, guanine, and hypoxanthine (two ring compounds), electrical property calculations using the AQZP basis set were not carried out (cf., Table I) because the computational time spent in these cases increase significantly.…”

Section: Resultsmentioning

confidence: 99%

“…Table II gives the calculated HF, BP86, and B3LYP/ADZP static polarizabilities for benzene, pyridine, nucleic acid bases, and three related bases, as well as theoretical results from Ref. [17] and experimental data [21][22][23] reported in the literature. For thymine, cytosine, adenine, guanine, benzene, and pyridine, our HF mean polarizabilities are in excellent agreement with the experimental data.…”

Section: Electric Dipole Momentmentioning

confidence: 99%

“…The latter two -conjugated molecules are important because the number of experimental data of electric properties available in the literature is larger and, then, we can better evaluate the accuracy that can be achieved with the models used in this work. Full geometry optimization for benzene and pyridine as well as calculated static values of the dipole moment magnitude () and dipole polarizability (␣ ) are presented and compared with previous theoretical [17] and experimental [4,[21][22][23] results. The effects of basis set enlargements and correlation corrections on the dipole moment and dipole polarizability were examined in this work.…”

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confidence: 98%

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Basis set convergence of electric properties in HF and DFT calculations of nucleic acid bases

Campos

Jorge

2008

Int J of Quantum Chemistry

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ABSTRACT:Recently, a hierarchical sequence of augmented basis sets of double, triple, and quadruple zeta valence quality plus polarization functions (AXZP, X ϭ D, T, and Q) for the atoms from H to Ar were presented by Jorge et al. We report a systematic study of basis sets required to obtain accurate values of several electric properties for benzene, pyridine, the five common nucleic acid bases (uracil, cytosine, thymine, guanine, and adenine), and three related bases (fluorouracil, 5-methylcytosine, and hypoxanthine) at their full optimized geometries. Two methods were examined: Hartree-Fock (HF) and density functional theory (DFT). Including electron correlation decreases the magnitude of the dipole moment and increases the mean polarizability and also the polarizability anisotropy for every molecule. Calculated B3LYP/ADZP dipole moments and dipole polarizabilities show good agreement with both experimental and ab initio results based on second-order Mller-Plesset perturbation theory calculations. We have also showed that a basis set of double zeta quality is enough to obtain reliable and accurate electric property results for this kind of compounds.

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Molecular polarisability. Quinoxaline and some of its derivatives

Cited by 11 publications

References 0 publications

Photoabsorption and Photoionization Cross Sections of Pyridine in the Vacuum-Ultraviolet Energy Range

Photoabsorption and Photoionization Cross Sections of Pyridine in the Vacuum-Ultraviolet Energy Range

Diethyl 2-(2,3-diphenylquinoxalin-6-ylaminomethylene)malonate

Basis set convergence of electric properties in HF and DFT calculations of nucleic acid bases

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