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Complexation of fullerenes with 5,5'-Biscalix
1Department of Chemistry, Texas Christian University, Fort Worth, Texas 76129, USA.
The Journal of Organic Chemistry
|December 2, 2000
Summary
5,5'-Biscalix[5]arene forms stable complexes with C(60) and C(70) fullerenes. Structural analysis reveals a clamshell-like complex with C(60), indicating a conformational change in the biscalixarene.
Area of Science:
- Supramolecular Chemistry
- Materials Science
- Organic Chemistry
Background:
- Calixarenes are versatile macrocyclic compounds with tunable host-guest properties.
- Fullerenes (C(60) and C(70)) are important carbon allotropes with unique electronic and structural characteristics.
- Designing selective receptors for fullerenes remains a key challenge in supramolecular chemistry.
Purpose of the Study:
- To synthesize and characterize a novel biscalixarene derivative.
- To investigate the complexation behavior of the synthesized biscalixarene with C(60) and C(70) fullerenes.
- To elucidate the structural basis of the host-guest interaction through X-ray crystallography.
Main Methods:
- Oxidative coupling reaction for the synthesis of 5,5 '-Biscalix[5]arene.
- Spectroscopic techniques (NMR, Mass Spectrometry) for characterization.
- X-ray crystallographic analysis of the free ligand and the C(60) complex.
- UV-Vis titration for determination of association constants.
Main Results:
- 5,5 '-Biscalix[5]arene was successfully synthesized and characterized, revealing an o,u,u,d,u conformation in its tetrabenzoyl ester precursor.
- The biscalixarene forms stable complexes with both C(60) (K(assoc) = 43 M(-)(1)) and C(70) (K(assoc) = 233 M(-)(1)).
- X-ray crystallography of the C(60) complex shows a distinct clamshell-shaped architecture, attributed to a conformational switch from anti to syn upon complexation.
Conclusions:
- The synthesized 5,5 '-Biscalix[5]arene acts as an effective host for C(60) and C(70) fullerenes.
- The observed conformational change is crucial for the efficient binding of the fullerene guests.
- This study provides valuable insights into the design of macrocyclic hosts for fullerene recognition.
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