1,2-Diphenylbenzene (<i>o</i>-terphenyl)

Aikawa, Shunichi; Maruyama, Yooichiroh; Ohashi, Yoko; Sasada, Yoshio

doi:10.1107/s0567740878009577

Cited by 45 publications

(32 citation statements)

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“…These values were comparable with torsion angles (60–80°) between benzene rings and heterocyclic rings of N,N ′, N ″‐triphenylisocyanurates in crystal . The dihedral angles ( ψ ) between Ph 2 and Ph 3 were 56.4–74.5° which are larger than those (~ 50°) between two benzene rings of ortho‐terphenyl in crystal . Furthermore, the spatial distances ( d s) between the carbons of Ph 3 s and the hydrogens at ortho positions of Ph 1 s were 3.10–3.32 Å, being longer than those between hydrogens and aromatic rings in molecular structures formed by C―H···π‐arene interactions .…”

Section: Resultssupporting

confidence: 50%

Isocyanurates with Planar Chirality: Design, Optical Resolution, and Isomerization

et al. 2012

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Designs and syntheses of isocyanurates (1-3) are described on the basis of a novel concept that two enantiotopic faces of C(s) -symmetric, prochiral planar molecules are differentiated with a location of groups at the top or bottom of the planar skeleton using a rigid linker. Such isocyanurates are atropisomeric. The planar-chiral structures of 1 and 2(anti) (anti-conformer of 2) were confirmed by single-crystal X-ray analyses, and the space groups were P1 (for 1) and P2(1)/c (for 2(anti)), resulting that the crystals were racemates. Optical resolutions of 1-3 were successfully accomplished by using chiral high-performance liquid chromatography technique in combination with circular dichroism, absorption, and nuclear magnetic resonance spectroscopies and mass spectrometry. Furthermore, the rotational barriers (ΔG(‡)s) related to isomerizations of 1-3 were estimated to be 27.2 (for 1 at 50 °C), 27.6 (for 2(anti) at 50 °C), and 40.6 (for 3(syn) at 150 °C) kcal/mol. The ΔG(‡)s of 2 and 3 were higher than that of 1 and, in particular, that of 3 was highest among them. This result indicates that an introduction of bulky substituents and an intramolecular bridging are effective for inhibitions of the isomerizations.

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Section: Resultssupporting

confidence: 50%

Isocyanurates with Planar Chirality: Design, Optical Resolution, and Isomerization

et al. 2012

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“…4.1, Structure Structural information on OTP is available from the neutron [19] and X-ray [21] diffraction studies of crystals. It crystallized in the orthorhombic space group P2,2,2, (Di) with four molecules in the unit cell in general positions.…”

Section: Resultsmentioning

confidence: 99%

Molecular vibrations and lattice dynamics of ortho-terphenyl

Baranović¹,

Bistričić

Volovšek

et al. 2001

Molecular Physics

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Infrared and Raman spectra of crystalline, melted and solvated orfho-terphenyl and its perdeuterated isotopomer, D14-ortho-tephenyl, have been recorded. Optimized geometries and vibrational frequencies were calculated by the semiempirical RHF/AM 1 method and by DFT using the B3LYP functional and 6-31G(d) basis set. In both cases the lowest energy conformation is of C2 symmetry. With the scaled AM1 and B3LYP/6-31G(d) force fields the average error in reproducing the experimental molecular vibrational frequencies is 13 cm-' and 5cm-*, respectively. The AM1 potential energy surface for phenyl torsions was mapped on a 15" grid. The barrier to concerted internal rotation is estimated to lie between 3 kJ mol-' and 6 kJmol-'. The calculations of the lattice dynamics at k = 0 in the low temperature fully ordered crystal phase of parent and deuterated ortho-terphenyl were performed with inclusion of six low lying intramolecular vibrations. The conformational change of the ortho-terphenyl molecule induced by crystal packing forces was taken into account by re-defining the unperturbed molecular vibrational state. Although an accurate assignment of lattice vibrations was not possible, the calculated spectra give quite a reasonable picture of the low frequency dynamics in crystalline ortho-terphenyl. The relevance of the results obtained to the glass forming property of ortho-terphenyl is discussed.The present study is an attempt to complete the assignment of the vibrational spectrum of OTP using both Raman and IR spectroscopy and to incorporate scaled semiempirical and DFT quantum mechanical calculations with subsequent use of these results in crystal dynamics calculations. Particularly interesting in the vibrational dynamics of OTP is the assignment of the low frequency intramolecular modes, and the evaluation of their possible role in the formation of the glassy state. There has been speculation in the literature about whether torsional motion of the side phenyl rings is responsible for the secondary relaxation in OTP. A secondary or ,&relaxation in the OTP glass was observed by dielectric relaxation [5] and by neutron diffraction 121. An important contribution in this respect is the molecular dynamics simulation study [lo], in which an empirical intramolecular torsional potential was used. A qualitative picture of the short-term dynamics in OTP has been achieved without, however, stating explicitly the extent to which side ring flips are responsible for the secondary, either fast or slow, relaxation. ExperimentalThe OTP sample was purchased from Aldrich and used without further purification. The sample of per-Molecular Physics ISSN 0026-8976 print/ISSN 1362-3028 online 0 2001 Taylor

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“…The o-Terphenyl has the most distorted structure of the three isomers because of the obvious steric repulsion between the adjacent phenyl rings, the two rings having a different rotation angle along the Ph-Ph bond of approximately +42°and +62°in the crystal [23,24] and an equal one of +53°(average value) in the isolated molecule [31]. Furthermore, the angles between the Ph-Ph bonds and the C-C bond in the middle ring to which the outer phenyl rings are connected are greater than 120°, more specifically a 1 = 123.6°a nd a 2 = 123.0°in the crystal and a 1 = a 2 = 122.9°in the gas phase [29], confirming the steric hindrance between the outer phenyl rings.…”

Section: Discussionmentioning

confidence: 99%

“…For this purpose, much work has been developed over the years. Previous investigations were done in order to determine the crystal structures of both o-terphenyl [23,24] and p-terphenyl [25,26]. This was closely accompanied by the calculation of the inter-and intramolecular potentials and of conformational analysis of each terphenyl isomer in both solid and gaseous states and also in solution [26][27][28][29][30][31][32], determining bond angles, Ph-Ph minimum energy torsion angles, rotation barrier heights, existence of conformers and phase transitions.…”

Section: Introductionmentioning

confidence: 99%