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Expanding Cavitand Chemistry: The Preparation and Characterization of [ n ]Cavitands with n ≥4
Author(s) -
Naumann Christoph,
Román Esteban,
Peinador Carlos,
Ren Tong,
Patrick Brian O.,
Kaifer Angel E.,
Sherman John C.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010417)7:8<1637::aid-chem16370>3.0.co;2-x
Subject(s) - cavitand , chemistry , steric effects , crystallography , computational chemistry , stereochemistry , supramolecular chemistry , crystal structure
The preparation of cavitands composed of 4, 5, 6, and 7 aromatic subunits ([ n ]cavitands, n =4–7) is described. The simple, two‐step synthetic procedure utilized readily available starting materials (2‐methylresorcinol and diethoxymethane). The two cavitand products having 4 and 5 aromatic subunits exhibited highly symmetric cone conformations, while the larger cavitands ( n =6 and 7) adopt conformations of lower symmetry. 1 H NMR spectroscopic studies of [6]cavitand and [7]cavitand revealed that these hosts undergo exchange between equivalent conformations at room temperature. The departure of these two cavitands from cone conformations is related to steric crowding on their Ar‐O‐CH 2 ‐O‐Ar bridges and is predicted by simple molecular mechanics calculations (MM2 force field). X‐ray diffraction studies on single crystals of the [4]cavitand, [5]cavitand, and [6]cavitand hosts afforded additional experimental support for these conclusions.