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Molecular recognition by wall-assembling-type nanocavity in aqueous media.
Katsuhiko Ariga1, Daisuke Sakai, Toshiyuki Ogata
1Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0101, Japan.
Journal of Nanoscience and Nanotechnology
|August 12, 2003
Summary
Novel steroid cyclophanes bind guests through hydrogen bonding. This interaction, confirmed by circular dichroism, creates a hydrophobic nanocavity, fixing the guest
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Biochemistry
Background:
- Steroid cyclophanes are macrocyclic compounds with potential applications in molecular recognition.
- Bile acids and lysine are key components in constructing these complex molecular architectures.
Purpose of the Study:
- To synthesize novel steroid cyclophanes and investigate their guest-binding properties in aqueous solutions.
- To elucidate the binding mechanism using spectroscopic techniques.
Main Methods:
- Synthesis of steroid cyclophanes incorporating bile acid moieties and chiral lysine connectors.
- Investigation of guest binding using circular dichroism (CD) spectroscopy.
- Analysis of induced circular dichroism (ICD) signals.
Main Results:
- Steroid cyclophanes showed significant changes in CD spectra upon binding with 2-naphthylphenylketone (guest).
- Specific binding interactions, including hydrogen bonding between the guest and host, were identified.
- Chirality of lysine influenced the sign of molecular ellipticities in the CD spectra.
Conclusions:
- The study demonstrates the formation of a hydrophobic nanocavity within the steroid cyclophane, facilitating guest binding.
- Hydrogen bonding between the guest's carbonyl group and the host's steroidal hydroxyl groups is crucial for conformational fixation.
- These findings highlight the potential of tailored steroid cyclophanes for molecular recognition and host-guest chemistry.