Etudes conformationnelles de dérivés d'oligométhylène glycols et de composés apparentés. V. Structure cristalline et moléculaire du téréphtalate de méthyle, C10H10O4

Brisse, F.; Pérez, S.

doi:10.1107/s0567740876007218

Cited by 31 publications

(4 citation statements)

References 2 publications

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“…The molecular geometry ( C 2 h symmetry) was obtained from an ab initio geometry optimization performed with a 3-21G* basis set. This calculated structure is similar to the solid state crystal structure of 1,4-DMT, except that the lowest energy gas phase structure is planar whereas the methyl ester groups are nonplanar by ∼5° in the solid state. The procedures used to apply EHMO to core-excitation spectroscopy have been documented in earlier studies of organometallic, − conjugated organic, and polymer analogue molecules. , …”

Section: Methodssupporting

confidence: 61%

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

et al. 1997

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The C 1s and O 1s X-ray absorption spectra of poly(ethylene terephthalate) (PET) have been recorded using transmission, fluorescence, and electron yield detection. The corresponding electron energy loss spectra (EELS) have been recorded in a scanning transmission electron microscope. These results are compared to the C 1s and O 1s spectra of gas phase 1,4-dimethyl terephthalate (the monomer of PET) recorded using EELS. The comparison of monomer and polymer materials in different phases and with different techniques has aided the understanding of the relative strengths and limitations of each technique as well as assisting the spectral interpretation. Good agreement is found in the overall shape and the energies of the spectral features. Relatively minor differences in intensities can be understood in terms of the properties of the individual spectroscopic techniques. The critical dose for radiation damage by 100 keV electrons incident on PET at 100 K is found to be (1.45 ( 0.15) × 10 3 eV nm -3 . In contrast, the critical dose for radiation damage by 302 eV X-rays incident on PET at 300 K is (1.2 ( 0.6) × 10 4 eV nm -3 . A figure of merit involving the product of critical energy dose and spectral efficiency (as expressed by the appropriate G value) is developed. This indicates that, for near-edge studies involving a 20 eV spectral width, there is ∼500-fold advantage of X-ray absorption studies on room temperature PET relative to electron energy loss studies of cooled PET.

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Section: Methodssupporting

confidence: 61%

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

et al. 1997

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“…The stacking of molecules along the c -axis of 1 - 107 and along the a -axis of 1 - 112 (SC B ) is repeated in methyl 4-aminobenzoate 45 ( 2-II ), dimethyl terephthalate 46 ( 3 ), methyl 4-bromobenzoate 47 ( 4 ) and its iodo 47 ( 5 ) and ethynyl 48 ( 6 ) analogues, methyl 4-(bromomethyl)benzoate 49 ( 7 ) and methyl 4-methylbenzoate 50 ( 8 ). Form 1 - 112 is even 2D similar (SC C) with polymorph 2-II of 4-aminobenzoate, 45 with which it shares a centrosymmetric double layer consisting of two layers of H-bonded chains.…”

Section: Resultsmentioning

confidence: 99%

Four Polymorphs of Methyl Paraben: Structural Relationships and Relative Energy Differences

Gelbrich

Braun

Ellern

et al. 2013

Crystal Growth & Design

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Four polymorphic forms of methyl paraben (methyl 4-hydroxybenzoate, 1), denoted 1-I (melting point 126 °C), 1-III (109 °C), 1-107 (107 °C), and 1-112 (112 °C), have been investigated by thermomicroscopy, infrared spectroscopy, and X-ray crystallography. The crystal structures of the metastable forms 1-III, 1-107, and 1-112 have been determined. All polymorphs contain the same O–H···O=C connected catemer motif, but the geometry of the resulting H-bonded chain is different in each form. The Z′ = 3 structure of 1-I (stable form; space group Cc) contains local symmetry elements. The crystal packing of each of the four known crystal structures of 1 was compared with the crystal structures of 12 chemical analogues. Close two-dimensional relationships exist between 1-112 and a form of methyl 4-aminobenzoate and between 1-107 and dimethyl terephthalate. The lattice energies of the four methyl paraben structures have been calculated with a range of methods based on ab initio electronic calculations on either the crystal or single molecule. This shows that the differences in the induction energy of the different hydrogen-bonded chain geometries have a significant effect on relative lattice energies, but that conformational energy, repulsion, dispersion, and electrostatic also contribute.

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“…It is approximately planar and possesses inversion symmetry. DMT crystallizes in the orthorhombic sequence proper, we applied a composite 45Њ x -90Њ y preparation pulse in order to flip the initial thermal equilibrium spacegroup Pbca with four molecules in the unit cell (10). This implies that in the crystal there are four magnetically magnetization into the plane perpendicular to the effective field acting during the BR-24 cycle (it points along the 111 inequivalent but crystallographically equivalent methyl groups and that it is sufficient to specify the CS tensor of a direction of the rotating frame).…”

Section: Introductionmentioning

confidence: 99%

Proton Chemical-Shift Tensors of Methyl Groups; a Multiple-Pulse NMR and LORG/IGLOab InitioStudy

Tesche

Haeberlen

1995

Journal of Magnetic Resonance, Series A

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Etudes conformationnelles de dérivés d'oligométhylène glycols et de composés apparentés. V. Structure cristalline et moléculaire du téréphtalate de méthyle, C₁₀H₁₀O₄

Cited by 31 publications

References 2 publications

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

Spectromicroscopy of Poly(ethylene terephthalate): Comparison of Spectra and Radiation Damage Rates in X-ray Absorption and Electron Energy Loss

Four Polymorphs of Methyl Paraben: Structural Relationships and Relative Energy Differences

Proton Chemical-Shift Tensors of Methyl Groups; a Multiple-Pulse NMR and LORG/IGLOab InitioStudy

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