@article{HansenKochKleinpeter2018,
  author    = {Hansen, Poul Erik and Koch, Andreas and Kleinpeter, Erich},
  title     = {Ring current and anisotropy effects on OH chemical shifts in resonance-assisted intramolecular H-bonds},
  series = {Tetrahedron letters},
  volume    = {59},
  journal   = {Tetrahedron letters},
  number    = {23},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4039},
  doi       = {10.1016/j.tetlet.2018.05.006},
  pages     = {2288 -- 2292},
  year      = {2018},
  abstract  = {Ring current effects on resonance-assisted and intramolecularly bridged hydrogen bond protons for 10-hydroxybenzo[h]quinoline 1 and a number of related compounds were calculated and the through-space NMR shieldings (TSNMRS) obtained hereby visualized as iso-chemical-shielding surfaces (ICSS) of various size and direction. These calculations revealed that this through-space effect is comparably large (up to 2 ppm) dependent on the position of the intramolecularly bridged OH proton, and therefore, contribute considerably to the chemical shift of the latter making it questionable to use delta(OH)/ppm in the estimation of intramolecular hydrogen bond strength without taking this into account. Furthermore, the anisotropy effects of additional groups on the aromatic moiety (e.g. the carbonyl group in salicylaldehyde or in o-hydroxyacetophenone of ca. 0.6 ppm deshielding) should also be considered. These through-space effects need to be taken into account when using OH chemical shifts to estimate hydrogen bond strength.},
  language  = {en}
}
@article{KleinpeterKoch2011,
  author    = {Kleinpeter, Erich and Koch, Andreas},
  title     = {The anisotropic effect of functional groups in H-1 NMR spectra is the molecular response property of spatial NICS-the frozen conformational equilibria of 9-arylfluorenes},
  series = {Tetrahedron},
  volume    = {67},
  journal   = {Tetrahedron},
  number    = {32},
  publisher = {Elsevier},
  address   = {Oxford},
  issn      = {0040-4020},
  doi       = {10.1016/j.tet.2011.06.005},
  pages     = {5740 -- 5743},
  year      = {2011},
  abstract  = {Rotation about the single bond adjoining the aryl and fluorene moieties in 9-arylfluorenes can be frozen out on the NMR timescale if methyl groups are located at either one or both of the ortho positions of the aryl substituent. In the ground-state of these rotamers, the planes of the aryl and fluorene moieties are perpendicular to each other and the methyl substituents are consequently positioned either above the fluorene moiety or in-plane with it; thus, the methyl protons are either shielded or deshielded, respectively, due to the ring current effect of the fluorene moiety. This anisotropic effect on the H-1 chemical shifts of the methyl protons has been quantified on the basis of through-space NMR shieldings (TSNMRS) and subsequently Delta delta(calcd) compared with the experimentally observed chemical shift differences, Delta delta(exp). In this context, the experimental anisotropic effects of functional groups in the H-1 NMR have proven to quantitatively be the molecular response property of theoretical spatial nucleus independent chemical shieldings (NICS). Differences between Delta delta(calcd) and Delta delta(exp) were, for the first time, also quantified as arising from steric compression.},
  language  = {en}
}