Solid state conformations of symmetrical aromatic biheterocycles: an X-ray crystallographic investigation

Fitchett, Christopher M.; Richardson, Christopher; Steel, Peter J.

doi:10.1039/b416553e

Cited by 44 publications

(38 citation statements)

References 35 publications

(16 reference statements)

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“…[1][2][3] Examples include protein-ligand complexation, 4 DNA base stacking, 5 supramolecular chemical recognition, [6][7][8] selectivity in chemical reactions, 9 aggregation and solvation of carbon nanostructures, 10 and petroleum phase behaviour. 11,12 Unlike other non-covalent interactions, such as hydrogen or halogen bonding, aromatic interactions do not arise from one single dominant interatomic mechanism.…”

Section: Introductionmentioning

confidence: 99%

The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

Headen

Cullen

Patel

et al. 2018

Phys. Chem. Chem. Phys.

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Total neutron scattering has been used in conjunction with H/D and *N/ 15 N isotopic substitution to determine the detailed liquid-state structures of pyridine and naphthalene. Analysis of the data via an empirical potential-based structure refinement method has allowed us to interrogate the full six-dimensional spatial and orientational correlation surfaces in these systems, and thereby to deduce the fundamental effects of a heteroatom and aromatic core-size on intermolecular p-p interactions. We find that the presence of a nitrogen heteroatom, and concomitant dipole moment, in pyridine induces surprisingly subtle departures from the structural correlations observed in liquid benzene: in both cases the most probable local motif is based on perpendicular (edge-to-face) intermolecular contacts, while parallel-displaced configurations give rise to a clear shoulder in the correlation surface. However, the effect of the heteroatom is revealed through detailed analysis of the intermolecular orientational correlations. This analysis shows a tendency for neighbouring pyridine molecules to direct one meta-and one para-hydrogen towards the neighbouring aromatic p-orbitals in edge-to-face configurations, while head-to-tail alignment of adjacent nitrogen atoms is favoured in faceto-face configurations. In contrast to this, increasing aromatic core size from one to only two rings has a clear and profound effect on the p-p interactions and liquid structure. Our experiments show that naphthalenenaphthalene contacts are dominated by parallel-displaced configurations, akin to those found in graphite. This marks a fundamental difference with the structure of liquid benzene, in which perpendicular geometries are favoured. Furthermore, it is remarkable to note that in the systems studied, the most favoured spatioorientational configurations observed in the liquid state are not predicted from ab initio calculations and/or solid state crystallographic studies. This highlights the need for caution when extrapolating the results of crystallographic and computational studies to aromatic interactions in liquids and disordered systems.

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Section: Introductionmentioning

confidence: 99%

The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

Headen

Cullen

Patel

et al. 2018

Phys. Chem. Chem. Phys.

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“…Both crystal structures were solved and refined in the orthorhombic space group P2 1 2 1 2 1 and crystallographic data are detailed in Table 1. The structures of L1 and L2 both display the expected 17 trans-coplanar orientations of the pyridine-indazole system, Fig. 1.…”

Section: Resultsmentioning

confidence: 99%

Discrete and polymeric Cu(ii) complexes featuring substituted indazole ligands: their synthesis and structural chemistry

Hawes

Kruger

2014

Dalton Trans.

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Reported here are the syntheses of four indazole-based ligands and the structural characterisation of four Cu(II) complexes derived from them. The ligands 1-(2-pyridyl)-1H-indazole, L1, and 2-(2-pyridyl)-2H-indazole, L2, have been characterised by single crystal X-ray diffraction methods for the first time. The intramolecular structural changes within L1 and L2 that result from the transition from the 1H to the 2H electronic configuration have been delineated. The synthesis of 1H-indazole-6-carboxylic acid, H 2 L3, and 1H-indazole-7-carboxylic acid, H 2 L4, is fully described and the structure of H 2 L4·H 2 O determined. The structures of two discrete mononuclear complexes {[Cu (L1)

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“…In addition, such rotations around formal single bonds are particularly sensitive to medium effects and differences of up to 30j are not uncommon. 54 Electronic Excitation Energies of Hyperolactone C Experimentally, in acetonitrile solution a broad maximum around 300 nm (log q = 3.75) and a less intense one around 250 nm (log q = 3.45) is observed. In EtOH, UV absorptions at 307 nm (log q = 4.41) and 254 nm (log q = 4.15) have been reported.…”

Section: Structural Properties Of Hyperolactone Cmentioning

confidence: 96%

Hyperolactone C: Determination of its absolute configuration by comparison of experimental and calculated CD spectra

Schühly¹,

Crockett²,

Fabian³

2005

Chirality

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A detailed conformational analysis of hyperolactone C diastereomers and enantiomers ((5R,9R),(5S,9S) and (5S,9R),(5R,9S)) was done with molecular mechanics and density functional theory methods. Time-dependent density functional theory (B3PW91/TZVP) was used to calculate electronic transition energies (UV/vis spectra) and rotational strengths of the respective conformations. The effect of solvation (acetonitrile solution) on excitation energies and electronic circular dichroism was approximated by the polarizable continuum model. By comparison of the simulated CD spectrum with that measured for hyperolactone C isolated from Hypericum lloydii, its absolute configuration can be assigned as (5S,9S).

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Solid state conformations of symmetrical aromatic biheterocycles: an X-ray crystallographic investigation

Cited by 44 publications

References 35 publications

The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

The structures of liquid pyridine and naphthalene: the effects of heteroatoms and core size on aromatic interactions

Discrete and polymeric Cu(ii) complexes featuring substituted indazole ligands: their synthesis and structural chemistry

Hyperolactone C: Determination of its absolute configuration by comparison of experimental and calculated CD spectra

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