Ligands for the alkali metals. Part 7. Synthesis and characterisation of crown ether macrocycles containing the di-1-naphthylmethyl unit as a novel steric barrier

Abstract

The first examples of crown ethers in which each end of the ether strand is fixed to one blade of a molecular propeller (a dinaphthylmethane) have been synthesised. The resultant steric barriers have been found to slow crown-flexing sufficiently for kinetic processes to be observed with ¹H or ¹³C n.m.r. in the temperature range 200–270 K. vic-Coupling constants for the ethylene oxide segments at ambient temperature indicate a very low proportion of trans-conformer in the conformational mix. The crowns also complex with the alkali cations in solution.