18375-61-6Relevant articles and documents
Spectral insights into gelation microdynamics of N-octyl-D-gluconamide in water
Sun, Shengtong,Wu, Peiyi
, p. 6451 - 6456 (2011)
Near infrared spectroscopy in combination with two-dimensional correlation spectroscopy (2Dcos) and perturbation correlation moving window (PCMW) technique is employed to illustrate the gelation microdynamic mechanism of hydrogelator N-octyl-D-gluconamide (8-GA), which can rapidly self-agglomerate into helical bilayer micellar fibers upon cooling from spherical micelles. Boltzmann fitting and PCMW easily determined the gelation temperature to be ca. 72°C and the transition temperature range to be 70-75°C. Moreover, band shifting and splitting phenomena can be observed for CH-related overtones, indicating the formation of much ordered and tight hydrophobic core from octyl tails. On the other hand, 2Dcos was used to discern the sequential orders during the gelation process and concluded that all the group motions have a continuous transfer from the octyl tail to the chiral carbohydrate head followed by the final immobilization of the solvent, which meanwhile, is actually a continuous dehydration process from the hydrophobic core to the outer hydrophilic chiral head. The driving force of the gelation process in microdynamics can only be the dehydration process of hydrophobic octyl chains, but with final helical superstructures being stabilized by amide-associated hydrogen bonding and the "chiral bilayer effect" of carbohydrate heads.
Face specific surface properties of pharmaceutical crystals
Muster, Tim H.,Prestidge, Clive A.
, p. 1432 - 1444 (2002)
A variety of surface specific techniques have been used to determine the face-specific structure, chemistry, and wettability of model pharmaceutical crystals, i.e., N,n-octyl-D-gluconamide and sulfathiazole (polymorphic forms I and III). The surface energetics of individual crystal faces were investigated by studying their wetting characteristics and interaction with chemically modified silica spheres using colloid probe atomic force microscopy (AFM). Contact angles (dynamic and static), interaction forces, and adhesion properties have been shown to correlate strongly with the face specific surface chemistry. This, in turn, is controlled by the molecular arrangement at the specific crystal face, which has been characterized by time-of-flight secondary-ion mass spectrometry (ToF SIMS) and inferred from molecular models. Of specific note, the magnitude of the adhesion force between a crystal face and a hydrophobic colloid probe is related linearly to the face-specific equilibrium contact angle. These studies further our understanding of the face-specific properties of pharmaceutical crystals and have implications when considering processing, formulation and delivery.
Crystalline Order in Probably Hollow Micellar Fibers of N-Octyl-D-gluconamide
Svenson, Soenke,Koenig, Juergen,Fuhrhop, Juergen-Hinrich
, p. 1022 - 1028 (1994)
The molecular conformation of N-(1-octyl)-D-gluconamide in its helical micellar fibers is determined.The all-anti conformation in three-dimensional crystals and the 4G+ conformation in DMSO solution served as references.Comparisons of 13C CP/MAS solid-state NMR spectra of head-to-tail and tail-to-tail oriented crystals led to a 2G- conformation for the gluconamide head groups and all-anti conformation for the alkyl chains in the fibers.The latter result is confirmed by power X-ray diffraction date and infrared spectra.Modeling of the micellar rod shows that there must be a gap of about 0.8-nm diameter in the center, probably in the form of a tunnel.A short discussion of other cylindrical bilayer crystals is given.
