Solution conformation of septamycin and its sodium salt.

Abstract
The interpretation of the 300 MHz 1H-NMR spectra of septamycin (1) and its Na salt (1+) permits extraction of most of the parameters revealing their resemblant conformations in solution. The backbone forms a pseudocyclic structure closed by head-to-tail H bonding between the carboxylate fragment and the OH-14. In 1+, the Na+ is trapped in a central hole by coordinating around it 6-7 O atoms (including COO-). The external lipophilic zone of the molecule keeps the Na+ away from the surroundings. The dangling sugar-like fragment does not participate in the metal binding. It was not possible to detect any H2O molecule participating in the cyclization of septamycin-free acid, nor in septamycin-Na+, as was found in an X-ray study for the p-bromophenacyl ester.

This publication has 2 references indexed in Scilit: