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Nonactin, monactin, dinactin, trinactin, and tetranactin. A Raman spectroscopic study
Author(s) -
Phillies George D. J.,
Asher Irvin M.,
Stanley H. Eugene
Publication year - 1975
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1975.360141107
Subject(s) - chemistry , triclinic crystal system , hydrogen bond , raman spectroscopy , monoclinic crystal system , crystallography , stereochemistry , ion , crystal structure , medicinal chemistry , organic chemistry , molecule , physics , optics
Raman spectra are reported for crystalline nonactin, monactin, dinactin, trinactin, and tetranactin and their solutions in CCl 4 , CHCl 3 , CH 3 OH, and 4:1 (v/v) CH 3 OH:CHCl 3 . The macrotetrolide nactins selectively bind a wide variety of cations, and are important model compounds for the study of ion complexation. The conformations of nonactin, monactin, and dinactin in solution are similar. Their conformations are found to be sufficiently open to permit the ester carbonyl groups to form hydrogen bonds with CH 3 OH; this gives rise to characteristic changes in the vibration frequencies associated with the ester groups. Nonactin, which is the least soluble of the nactins in CH 3 OH, is also the least effective at forming hydrogen bonds with CH 3 OH. The greater ability of the higher nactins to form hydrogen bonds with CH 3 OH may be due to the increased inductive effect of ethyl over methyl side chains, which may increase the dipole moment of the ester carbonyl groups. Spectra of crystalline nonactin, monactin, and tetranactin are fairly similar, while the spectra of dinactin and trinactin comprise a second, distinct family. This is consistent with X‐ray crystallographic studies, which show that nonactin and tetranactin form monoclinic crystals, while trinactin is triclinic.