Siamwiza MN, Mwila LK & Jere EH


Conformations of Macrobicyclic Polyethers in Solution, by Mwindaace Siamwiza, L.K. Mwila and E.H. Jere, Zambia Journal of Science and Technology, Vol.5, October 1980, Pg. 8-17


Hydrogen bonding by Chloroform-d and the infra-red spectrum of its associated complex was used to study the conformations in solution of the polyethers. The polyethers 4,7,13,18-tetraoxa-l, 10-diazabicyclo(8.8.5)eicosane, (2.1.1.); 4,7,13,16,21-pentaoxa-l, 10-diazabicyclo (8.8.5)tricosane, (2.2.1) and 4,7,13,16,21,24-hexaoxa-l, 10 diazabicyclo(8.8.8)hexacosane, (2.2.2) were investigated and shown to exist mainly in the "out, out" conformation in solution.

The 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) was also investigated. It was shown that the oxygen atoms in this system are inaccessible to hydrogen bonding by chloroform-d. This indicates that the oxygen atoms in the polyethers (2.1.1), (2.2.1) and (2.2.2) do not appreciably form hydrogen bonds with chloroform-d and that only bridge-head nitrogen atoms participate in hydrogen bond formation.

Click here for the full article