Classical H-NMR shielding calculations with the program SHIFT and conformational analysis of three cyclophanes

Rüdiger, Volker; Schneider, Hans‐Jörg

doi:10.1002/(sici)1097-458x(200002)38:2<85::aid-mrc600>3.0.co;2-z

Cited by 7 publications

(4 citation statements)

References 51 publications

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“…He used molecular mechanics and chemical shifts to study the structure of a series of cyclophanes [106,107], using software developed for the calculation of the chemical shifts of steroids which were adapted for structure determination of complexes [108,109]. This program was tested on five cyclophanes and two cyclodextrin complexes in water.…”

Section: Molecular Mechanics Conformational Searchesmentioning

confidence: 99%

From structure to chemical shift and vice-versa

Hunter

Packer

Zonta

2005

Progress in Nuclear Magnetic Resonance Spectroscopy

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Section: Molecular Mechanics Conformational Searchesmentioning

confidence: 99%

From structure to chemical shift and vice-versa

Hunter

Packer

Zonta

2005

Progress in Nuclear Magnetic Resonance Spectroscopy

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“…p-Electrons are much more polarizable than r-electrons, therefore the field induced by p-electrons creates strong secondary field affecting neighbouring nuclei [17]. In this particular case, one of methyl groups of isobutyl moiety occupies the space in the vicinity of naphthyl ring causing the strong shielding of methyl protons, so the signals are shifted to low frequencies.…”

Section: Resultsmentioning

confidence: 99%

NMR and HPLC study of chiral selectors with naphthyl unit

et al. 2007

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Doubling of resonances in NMR spectra of chiral selectors with naphthyl group attached to the tertiary amide nitrogen atom has been noticed what revealed the presence of two isomers. To test the enantiorecognition ability of these chiral selectors they are covalently bonded to the HPLC silica gel. Those kind of chiral stationary phases were compared with analogous commercial leucine chiral stationary phase. They exhibit the better enantioseparation results which indicate that the existence of cis/ trans isomers does not have the negative influence on their enantioselective ability.

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“…By adding increasing amounts of a 1 × 10 -1 M solution of the guest to a 1 × 10 -2 M solution of the host in CDCl 3 , several signals of the receptors and of the guests were shifted upon complexation. In particular, with the 1:1 complex of 6 with acetamide, a downfield complexation induced shift (CIS) of ca. 1.0 ppm was experienced by both the two NH protons of the host, as expected on the base of their involvement in hydrogen bonding with the oxygen of the guest carbonyl group.…”

Section: Resultsmentioning

confidence: 99%

Recognition of Amides by New Rigid Calix[4]arene-Based Cavitands

2000

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The synthesis of new hosts specifically designed for the recognition of amides, characterized by two binding regions: a rigid calix[4]arene cavity and a sidearm, inserted at its rim, able to form strong hydrogen bonds, is described. The binding abilities of the new receptors toward amides of general structure R(1)CONR(2)R(3) have been investigated in CDCl(3) solution by (1)H NMR spectroscopy. When the additional binding site is the N-phenylureido group spaced by a methylene unit from the apolar cavity, binding constants up to 756 M(-)(1) were measured. Neither the two separate potential binding sites, nor the model host, where the calix[4]arene skeleton is flexible show detectable binding ability toward the series of guests examined. The rigidity of the calix[4]arene apolar cavity is the key control element in determining the efficiency of these molecular recognition processes. The presence of NH groups in the guest controls the efficiency and selectivity of binding.

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Classical H-NMR shielding calculations with the program SHIFT and conformational analysis of three cyclophanes

Cited by 7 publications

References 51 publications

From structure to chemical shift and vice-versa

From structure to chemical shift and vice-versa

NMR and HPLC study of chiral selectors with naphthyl unit

Recognition of Amides by New Rigid Calix[4]arene-Based Cavitands

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