2 research outputs found
Encapsulation of Xenon by a Self-Assembled Fe<sub>4</sub>L<sub>6</sub> Metallosupramolecular Cage
We report <sup>129</sup>Xe NMR experiments
showing that a Fe<sub>4</sub>L<sub>6</sub> metallosupramolecular cage
can encapsulate xenon
in water with a binding constant of 16 M<sup>–1</sup>. The
observations pave the way for exploiting metallosupramolecular cages
as economical means to extract rare gases as well as <sup>129</sup>Xe NMR-based bio-, pH, and temperature sensors. Xe in the Fe<sub>4</sub>L<sub>6</sub> cage has an unusual chemical shift downfield
from free Xe in water. The exchange rate between the encapsulated
and free Xe was determined to be about 10 Hz, potentially allowing
signal amplification via chemical exchange saturation transfer. Computational
treatment showed that dynamical effects of Xe motion as well as relativistic
effects have significant contributions to the chemical shift of Xe
in the cage and enabled the replication of the observed linear temperature
dependence of the shift
Experimental and First-Principles NMR Analysis of Pt(II) Complexes With <i>O</i>,<i>O</i>′‑Dialkyldithiophosphate Ligands
Polycrystalline
bisÂ(dialkyldithiophosphato)ÂPtÂ(II) complexes of
the form [PtÂ{S<sub>2</sub>PÂ(OR)<sub>2</sub>}<sub>2</sub>] (R = ethyl, <i>iso</i>-propyl, <i>iso</i>-butyl, <i>sec</i>-butyl or <i>cyclo</i>-hexyl group) were studied using
solid-state <sup>31</sup>P and <sup>195</sup>Pt NMR spectroscopy,
to determine the influence of R to the structure of the central chromophore.
The measured anisotropic chemical shift (CS) parameters for <sup>31</sup>P and <sup>195</sup>Pt afford more detailed chemical and structural
information, as compared to isotropic CS and <i>J</i> couplings
alone. Advanced theoretical modeling at the hybrid DFT level, including
both crystal lattice and the important relativistic spin–orbit
effects qualitatively reproduced the measured CS tensors, supported
the experimental analysis, and provided extensive orientational information.
A particular correction model for the non-negligible lattice effects
was adopted, allowing one to avoid a severe deterioration of the <sup>195</sup>Pt anisotropic parameters due to the high requirements posed
on the pseudopotential quality in such calculations. Though negligible
differences were found between the <sup>195</sup>Pt CS tensors with
different substituents R, the <sup>31</sup>P CS parameters differed
significantly between the complexes, implying the potential to distinguish
between them. The presented approach enables good resolution and a
detailed analysis of heavy-element compounds by solid-state NMR, thus
widening the understanding of such systems