Conformations of Bridged Diphenyls. VI. Substituent Effects and Internal Rotation in Triply <i>Ortho</i>-substituted Diphenyl Ethers

Benjamins, Harm; Dar, Fazal Haque; Chandler, W. David

doi:10.1139/v74-487

Cited by 16 publications

(8 citation statements)

References 21 publications

(27 reference statements)

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“…This result is consistent with previous studies on substituted diphenyl ethers that indicate that the interconversion between the low‐energy minima occurs with a barrier of <10 kcal/mol, which is faster than the NMR timescale at room temperature. However, larger substituents on the diphenyl ether were shown to increase the barrier to 15 − 20 kcal/mol, and similar behavior was observed in this work for (Xan‐OH) 2 (vide infra).…”

Section: Resultssupporting

confidence: 83%

“…This result is consistent with previous studies on substituted diphenyl ethers that indicate that the interconversion between the low-energy minima occurs with a barrier of <10 kcal/mol, [27] which is faster than the NMR timescale at room temperature. However, larger substituents on the diphenyl ether were shown to increase the barrier to 15 À 20 kcal/mol, [37] and similar behavior was observed in this work for (Xan-OH) 2 (vide infra). The information regarding the rotation of the Xan + moiety (defined by dihedral angles C 6 -C 7 -C 8 -C 13 and C 6′ -C 7′ -C 8′ -C 9′ ) cannot be extracted in a straightforward manner from the NMR spectra, because of the C2v symmetry of the xanthylium moiety.…”

Section: Conformational Flexibility Of (Xan + )supporting

confidence: 84%

“…The rotation around the dihedral angles of substituted diphenyl ethers is known to occur by a cooperative motion of both phenyl rings through either skew‐ or butterfly‐type TSs . The reported barriers are in the 3 − 20 kcal/mol range, depending on the bulkiness of the substituents in the ortho positions.…”

Section: Resultsmentioning

confidence: 99%

“…The rotation around the dihedral angles of substituted diphenyl ethers is known to occur by a cooperative motion of both phenyl rings through either skew-or butterfly-type TSs. [27,37] The reported barriers are in the 3 À 20 kcal/mol range, depending on the bulkiness of the substituents in the ortho positions. In this study, the Xan + substituent is less bulky than the Xan-OH substituent, which leads to the observed trend in the rates for rotation: (Xan + ) 2 > Xan + -Xan-OH > (Xan-OH) 2 .…”

Section: Conformational Flexibility Of Xan + -Xan-ohmentioning

confidence: 99%

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Conformational flexibility of xanthene‐based covalently linked dimers

Zoric

Kadel

Korvinson

et al. 2016

J of Physical Organic Chem

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The conformational flexibility of three covalently linked dimers consisting of two xanthene‐based moieties connected by a diphenyl ether linker was studied using NMR spectroscopy, X‐ray crystallography, and density functional theory (DFT) calculations. The three dimers interconvert as a function of pH: the doubly cationic dimer (Xan+)2 exists in acidic solutions (pH < 0.5), the mono‐alcohol monocation Xan+–Xan‐OH at intermediate pH values (pH = 1–3), and the neutral diol at the highest pH‐values (pH > 3). Each dimer exhibits conformational degrees of freedom associated with rotations of either the xanthene moiety or of the diphenyl ether (DPE) linker. The barriers for rotation of the xanthylium moiety were evaluated using DFT calculations, yielding values of 23 kcal/mol for (Xan+)2 and 11 kcal/mol for (Xan‐OH)2, respectively. The rotational barrier for the diphenyl ether linker in Xan+–Xan‐OH (15 kcal/mol) was experimentally determined using variable temperature NMR measurements. The relative orientation of the two –OH groups in (Xan‐OH)2 diol was investigated in solution and the solid state using NMR spectroscopy and X‐ray crystallography. The conformer observed in the solid state was found to be the In–Out conformer, while free rotation of the xanthenol units is thought to occur on the NMR timescale at room temperature. These studies are relevant for the design of linkers for efficient water oxidation catalysts. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Resultssupporting

confidence: 83%

Section: Conformational Flexibility Of (Xan + )supporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Conformational Flexibility Of Xan + -Xan-ohmentioning

confidence: 99%

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Conformational flexibility of xanthene‐based covalently linked dimers

Zoric

Kadel

Korvinson

et al. 2016

J of Physical Organic Chem

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“…The synthesis of 2-(4'-carbomethoxy-2'-nitrophenyl-sulfony1)-1,3,5-trimethylbenzene, Cl7Hl7NO6S, has been reported earlier (8). The sample was recrystallized from 9 5 x ethanol, m.p.…”

Section: Methodsmentioning

confidence: 99%

Conformations of Bridged Diphenyls. XI. Crystal Structure of 2-(4′-Carbomethoxy-2′-nitrophenylsulfonyl)-1,3,5-trimethylbenzene

Heijden¹,

Chandler²,

Robertson³

1975

Can. J. Chem.

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The crystal structure of 2-(4′-carbomethoxy-2′-nitrophenylsulfonyl)-1,3,5-trimethylbenzene, C17H17NO6S, has been determined by X-ray diffraction. The crystals are triclinic, a = 12.907(13), b = 7.577(5), c = 9.1808(9) Å, α = 105.82(3), β = 112.81(5), γ = 93.97(4)°, [Formula: see text] with Z = 2. The integrated intensities of 3792 independent reflections were measured on a four circle diffractometer and 2985 reflections were used in the refinement to give a least-squares residual of 0.046 and a conventional R factor of 0.057.The molecule shows a twist-nitro-proximal conformation. However, the dihedral angles made by the mesityl ring and the nitro-substituted ring with the central C—S—C plane are dissimilar in contrast to the nearly equal angles found for the similarly substituted sulfinyl compound.

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Clathrate Formation from Octaazaphthalocyanines Possessing Bulky Phenoxyl Substituents: A New Cubic Crystal Containing Solvent‐Filled, Nanoscale Voids

Makhseed

Ibrahim

Samuel

et al. 2008

Chemistry A European J

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The synthesis of octaazaphthalocyanine (AzaPc) derivatives, with bulky phenoxyl substituents placed at eight peripheral positions and containing either H(+), Ni(2+) or Zn(2+) ions in their central cavity, is described. The required precursors, derivatives of pyrazine-2,3-dicarbonitrile, were prepared using a nucleophilic aromatic substitution reaction between 2,6-diisopropylphenol or 2,6-diphenylphenol and 5,6-dichloropyrazine-2,3-dicarbonitrile. Analysis of the resulting AzaPcs by UV/Visible and (1)H NMR spectroscopy confirms that steric isolation of the AzaPc cores was enforced both in solution and in the solid state. X-ray diffraction studies of single crystals of the AzaPcs reveal that solvent inclusion takes place in each case. Of particular significance is the finding that the zinc derivative of 2,3,9,10,16,17,23,24-octa-(2,6-diisopropylphenoxy)octaazaphthalocyanine provides nanoporous cubic crystals, containing massive (8 nm(3)) solvent-filled voids, similar to those of the analogous phthalocyanine derivative. Exchange of the included solvent within the voids can be readily achieved by using a number of alternative solvents including water. Based on the observed loading of included water, the internal volume of this nanoporous cubic crystal appears to be more hydrophilic than its phthalocyanine counterpart.

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Conformations of Bridged Diphenyls. VI. Substituent Effects and Internal Rotation in Triply Ortho-substituted Diphenyl Ethers

Cited by 16 publications

References 21 publications

Conformational flexibility of xanthene‐based covalently linked dimers

Conformational flexibility of xanthene‐based covalently linked dimers

Conformations of Bridged Diphenyls. XI. Crystal Structure of 2-(4′-Carbomethoxy-2′-nitrophenylsulfonyl)-1,3,5-trimethylbenzene

Clathrate Formation from Octaazaphthalocyanines Possessing Bulky Phenoxyl Substituents: A New Cubic Crystal Containing Solvent‐Filled, Nanoscale Voids

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