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Conformational changes in cryptophane having C1-symmetry studied by vibrational circular dichroism
Thierry Brotin1, Dominique Cavagnat, Thierry Buffeteau
1Laboratoire de Chimie de l'ENS-LYON (UMR 5182-CNRS), Ecole Normale Supérieure de Lyon, 69364 Lyon 07, France.
The Journal of Physical Chemistry. A
|August 20, 2008
Summary
Vibrational circular dichroism and DFT calculations determined the absolute configuration of cryptophane-H. Solvent affects linker conformation, influencing chiroptical properties and guest encapsulation.
Area of Science:
- Molecular Spectroscopy
- Computational Chemistry
- Supramolecular Chemistry
Background:
- Cryptophane molecules are known for their host-guest properties.
- Chiroptical properties are sensitive to molecular conformation and symmetry.
- Previous studies on D3-symmetric cryptophane-A exist.
Purpose of the Study:
- Determine the absolute configuration of C1-symmetric cryptophane-H.
- Investigate the influence of solvent on cryptophane-H conformation.
- Correlate conformational changes with chiroptical properties.
Main Methods:
- Vibrational circular dichroism (VCD) measurements.
- Density functional theory (DFT) calculations (B3PW91/6-31G*).
- Polarimetric measurements in various solvents.
Main Results:
- Absolute configuration of cryptophane-H was established.
- Conformation of aliphatic linkers is solvent-dependent.
- Chloroform encapsulation induces specific linker conformations (anti vs. gauche).
- Observed changes in chiroptical properties align with conformational shifts.
Conclusions:
- The study successfully determined the absolute configuration of cryptophane-H.
- Solvent plays a crucial role in modulating the conformational dynamics of cryptophane-H.
- Guest encapsulation and solvent interactions significantly impact the molecule's chiroptical behavior.
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