Structural and conformational studies of alcohol, diol and methyl ether derivatives of dibenzo-14-crown-4. Implications for ligand and tecton design

Uriel Olsher, Gil Shoham, N. Kent Dalley, Jiang Weining, Elzbieta Luboch, Zong Yuan Yu, John M. Knobeloch, Jong Chan Lee, Vladimir S. Talanov, Richard A. Bartsch*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Molecular structures are determined for six dibenzo-14-crown-4 derivatives that have one or two substituents on the central carbon(s) of the three-carbon bridge(s). The series of compounds includes three crown ether alcohols, one crown ether trans-diol, and two methoxy crown ether compounds. The crystal structures for these six crown ethers reveal that due to hydrogen-bonding and steric interactions, a hydroxy substituent is directed, at least partially, toward the crown ether cavity and an unusual intra- and intermolecular hydrogen bond network is formed between the hydroxy group protons and the ether oxygens of the crown ether ring. On the other hand, an ether group or a substituent with carbon as the first atom is oriented away from the polyether ring. The structure of sym-(methoxy)(methyl)dibenzo-14-crown-4 is markedly different from that of sym-(hydroxy)(methyl)dibenzo-14-crown-4 both in terms of the substituent orientation and very significant distortion from planarity of the four crown ether oxygens in the former. Support for an unusual conformation for sym-(methoxy)(methyl)dibenzo-14-crown-4 in solution is derived from 13C NMR measurements. Crown ether alcohols are hydrogen-bonding "tectons" that participate in strong, specific and directional intermolecular interactions.

Original languageAmerican English
Pages (from-to)2557-2564
Number of pages8
JournalJournal of the Chemical Society. Perkin Transactions 2
Issue number11
DOIs
StatePublished - Nov 1999

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