A series of nonionic sugar-based bolaamphiphiles having n-alkylene chain length of 9, 10, 11, 12, 13,
14, 16, or 18 carbon atoms, N,N
‘-bis(2-deoxy-d-glucopyranosid-2-yl)alkane-1,n-dicarboxamide, 1(
n
), have
been synthesized in one step from commercially available glucosamine hydrochloride. Their self-assembling
morphologies in 50% aqueous methanolic solutions have been studied using energy-filtering transmission
electron microscopy (EF-TEM). The bolaamphiphiles 1(
n
) (n = 10, 12, and 14) with an even-numbered
carbon bridge produced well-defined helically twisted fibers of 8−25 nm width with a high axial ratio. The
fiber morphology was found to display a pronounced even−odd dependence upon the number of carbons
(n) in the connecting alkylene bridge. A similar trend was also exhibited by the infrared band frequencies
and by the wide-angle X-ray diffraction patterns. Anomeric ratios of 1(
n
) were approximately constant
across the series and had no remarkable effect upon the fiber morphology.
Glucuronamide-based bolaamphiphiles are found to form a reversible, linear polymolecular array, via a boronate ester linkage attached to the 1,2-positions of the pyranose or furanose ring, upon complexation with an aromatic boronic acid-based homologue in aqueous solutions.
Concentration changes in supersaturated solutions during the nucleation and growth of the orthorhombic form of hen egg-white lysozyme crystals have been observed for 121 d at 35 degrees C and pH 4.6, and with 3% NaCl. The effect of a variation in the initial protein concentration on the rate of approach to solubility in equilibrium is analyzed, by applying a model, originally developed for the understanding of protein self-assembly. It is shown that the observed kinetics can be explained fairly well by this model, whose basic assumptions are that (a) the nucleation is induced by aggregation of i0 molecules into particular geometry, and (b) the growth proceeds via attachment of a monomer. The i0 value for this process is four, which agrees with the number of molecules in a unit cell. Similarity and dissimilarity of the observed crystal growth to that of low molecular weight substances are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.