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Influence of Ag(+) on the Magnetic Response of [2.2.2]Paracyclophane: NMR Properties of a Prototypical Organic Host for Cation Binding Based on DFT Calculations.

MacLeod Carey D, Gomez T, Morales-Verdejo C, Muñoz-Castro A - ChemistryOpen (2015)

Bottom Line: Through this study we sought a deeper understanding of the effects the metal center has on the NMR spectroscopic properties of the prototypical organic host, generating theoretical reasons for the observed experimental results with an aim to determine the role of the cation-π interaction in a host-guest scenario.From an analysis of certain components of the induced magnetic field and the (13)C NMR shielding tensor under its own principal axis system (PAS), the local and overall magnetic behavior can be clearly described.This proposed approach can be useful to gain further insight into the local and overall variation of NMR shifts for host-guest pairs involving both inorganic and organic hosts.

View Article: PubMed Central - PubMed

Affiliation: Facultad de Ingeniería, Universidad Autonoma de Chile Llano Subercaceaux 2801, San Miguel, Santiago, 780-0026, Chile.

ABSTRACT
The complexation of metal cations into a host-guest situation is particularly well exemplified by [2.2.2]paracyclophane and Ag(I), which leads to a strong cation-π interaction with a specific face of the host molecule. Through this study we sought a deeper understanding of the effects the metal center has on the NMR spectroscopic properties of the prototypical organic host, generating theoretical reasons for the observed experimental results with an aim to determine the role of the cation-π interaction in a host-guest scenario. From an analysis of certain components of the induced magnetic field and the (13)C NMR shielding tensor under its own principal axis system (PAS), the local and overall magnetic behavior can be clearly described. Interestingly, the magnetic response of such a complex exhibits a large axis-dependent behavior, which leads to an overall shielding effect for the coordinating carbon atoms and a deshielding effect for the respective uncoordinated counterparts, evidence that complements previous experimental results. This proposed approach can be useful to gain further insight into the local and overall variation of NMR shifts for host-guest pairs involving both inorganic and organic hosts.

No MeSH data available.


Related in: MedlinePlus

Map representation of through-space magnetic response (induced magnetic field), depicting the isotropic component and certain components of such tensor depicting the response under a specific orientation of the applied field.
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fig04: Map representation of through-space magnetic response (induced magnetic field), depicting the isotropic component and certain components of such tensor depicting the response under a specific orientation of the applied field.

Mentions: Due to the symmetry of the structure, the magnetic response of [Ag([2.2.2]pCp)]+ exhibits an axis-dependent behavior, which can be accounted for by the analysis of certain components of σij. The analysis of σzz, σxx, and σyy (Figure 3) denotes the difference when the external field is applied from the z, x, and y axes, respectively. From σzz, the enhancement of the shielding region near the Ag+ center is located along the z axis with a complementary deshielding region perpendicular to such axis. Thus, considering this particular example, the silver center will deshield the closer carbon atoms of [2.2.2]pCp (Figure 4).


Influence of Ag(+) on the Magnetic Response of [2.2.2]Paracyclophane: NMR Properties of a Prototypical Organic Host for Cation Binding Based on DFT Calculations.

MacLeod Carey D, Gomez T, Morales-Verdejo C, Muñoz-Castro A - ChemistryOpen (2015)

Map representation of through-space magnetic response (induced magnetic field), depicting the isotropic component and certain components of such tensor depicting the response under a specific orientation of the applied field.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608534&req=5

fig04: Map representation of through-space magnetic response (induced magnetic field), depicting the isotropic component and certain components of such tensor depicting the response under a specific orientation of the applied field.
Mentions: Due to the symmetry of the structure, the magnetic response of [Ag([2.2.2]pCp)]+ exhibits an axis-dependent behavior, which can be accounted for by the analysis of certain components of σij. The analysis of σzz, σxx, and σyy (Figure 3) denotes the difference when the external field is applied from the z, x, and y axes, respectively. From σzz, the enhancement of the shielding region near the Ag+ center is located along the z axis with a complementary deshielding region perpendicular to such axis. Thus, considering this particular example, the silver center will deshield the closer carbon atoms of [2.2.2]pCp (Figure 4).

Bottom Line: Through this study we sought a deeper understanding of the effects the metal center has on the NMR spectroscopic properties of the prototypical organic host, generating theoretical reasons for the observed experimental results with an aim to determine the role of the cation-π interaction in a host-guest scenario.From an analysis of certain components of the induced magnetic field and the (13)C NMR shielding tensor under its own principal axis system (PAS), the local and overall magnetic behavior can be clearly described.This proposed approach can be useful to gain further insight into the local and overall variation of NMR shifts for host-guest pairs involving both inorganic and organic hosts.

View Article: PubMed Central - PubMed

Affiliation: Facultad de Ingeniería, Universidad Autonoma de Chile Llano Subercaceaux 2801, San Miguel, Santiago, 780-0026, Chile.

ABSTRACT
The complexation of metal cations into a host-guest situation is particularly well exemplified by [2.2.2]paracyclophane and Ag(I), which leads to a strong cation-π interaction with a specific face of the host molecule. Through this study we sought a deeper understanding of the effects the metal center has on the NMR spectroscopic properties of the prototypical organic host, generating theoretical reasons for the observed experimental results with an aim to determine the role of the cation-π interaction in a host-guest scenario. From an analysis of certain components of the induced magnetic field and the (13)C NMR shielding tensor under its own principal axis system (PAS), the local and overall magnetic behavior can be clearly described. Interestingly, the magnetic response of such a complex exhibits a large axis-dependent behavior, which leads to an overall shielding effect for the coordinating carbon atoms and a deshielding effect for the respective uncoordinated counterparts, evidence that complements previous experimental results. This proposed approach can be useful to gain further insight into the local and overall variation of NMR shifts for host-guest pairs involving both inorganic and organic hosts.

No MeSH data available.


Related in: MedlinePlus