Solid state structure of dibenzo-crown ethers formally derived from resorcinol. X-ray crystal structure, solid state C-13 NMR and solution NMR properties of dibenzo-32-crown-10

摘要

The X-ray crystal structure of the title molecule indicates that all four O-C-C-O torsional networks possess normal gauche-type geometries. This is in contrast to the dibenzo-20-crown-6 and and dibenzo-26-crown-8 analogs in which at least one transoid O-C-C-O unit is present. C-13 NMR chemical shift differences are discussed in terms of the solid state geometry. In particular, there is a 7 ppm difference between two aromatic carbons which are ortho to oxygen, whereas in solution, the chemical shifts for these sites are identical due to conformational averaging. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 10]