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Conformational Switching of Resorcin[4]arene Cavitands by Protonation, Preliminary Communication
Author(s) -
Skinner Philip J.,
Cheetham Andrew G.,
Beeby Andrew,
Gramlich Volker,
Diederich François
Publication year - 2001
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(20010711)84:7<2146::aid-hlca2146>3.0.co;2-k
Subject(s) - chemistry , cavitand , protonation , quinoxaline , stereochemistry , nuclear magnetic resonance spectroscopy , crystallography , supramolecular chemistry , crystal structure , organic chemistry , ion
The synthesis of the quinoxaline‐bridged resorcin[4]arene cavitand 1 was accomplished from 2‐[3,5‐di( tert ‐butyl)phenyl]acetaldehyde via formation of the intermediate octol 2 . Such cavitands are known to occur in an open `kite' conformation at low temperature (<213 K) but to adopt a `vase' conformation at elevated temperatures (>318 K). We discovered that protonation of cavitand 1 at room temperature by common acids, such as CF 3 COOH, also causes reversible switching from `vase' to `kite', and that this conformational change can be conveniently monitored by both 1 H‐NMR and UV/VIS spectroscopy.