Solid-state NMR characterization of cyclomaltoheptaose (?-cyclodextrin) polymers using high-resolution magic angle spinning with gradients

Abstract

Solid-state nuclear magnetic resonance (NMR) techniques were used to characterize cyclomaltoheptaose (␤-cyclodextrin, ␤-CD) polymers. These insoluble materials have been investigated by cross-polarization magic angle spinning with dipolar decoupling (CP/MAS), magic angle spinning without dipolar decoupling (MAS), and high-resolution magic angle spinning with gradients (HRMAS). These NMR spectra allow the assignment of the principal 1 H and 13 C signals. The presence of two distinct components (cross-linked ␤-CD and polymerized epichlorohydrin) in the materials was clearly demonstrated. These polymers were used as sorbents and the resulting NMR spectra are presented and discussed.

HR-MAS NMR Spectroscopy in Material Science

“…[30,31] Other HR-MAS studies observed the impact of cross-linking in solvent swollen poly(amidoamine) polymers, the nature of water interactions in these same class of polymers, [32,33] or the cross-linking performance in silicon-containing soybean-oil copolymers. [34] HR-MAS NMR has also been used to study the functionalization of poly hydroxyethyl methacrylate (HEMA) cryogels, [35] cyclomaltoheptaose polymers, [36] the synthesis of hyper-branched bis (hydroxymethyl) propionic acid (bis-MPA) polymers as a function of catalysts, [37] and polymers for nanoparticle stabilization. [38] HR-MAS NMR has found use in investigation of porous polyalkylvinyl ether polymer particles being used for stationary phases in chromatographic applications.…”

Synthesis and applications of adsorbents containing cyclodextrins

“…In particular, the selective properties of CDs and their derivatives can be employed in all chromatographic techniques for the separation of structural, geometric, and optical isomers. They are used in HPLC [43, 44, 124 -127], TLC [42,128], GC [43, 45, 129 -131], affinity chromatography [132,133], ion-exclusion chromatography [134], preparative chromatography [135], electrophoresis [39,48,136,137] and micellar electrokinetic chromatography [40,138]. They were employed successfully as selective components in the mobile phase and as stationary phase.…”

“…In the literature, there have been numerous studies on the preparation [139 -152, 167 -176, 191 -198, 206 -217], characterization [19,40,140,149,152,184], properties [149 -152, 158], and applications [17 -20, 153 -200, 206 -217] of water insoluble materials containing CD molecules. There are several reported procedures for synthesizing these adsorbents and the methods can be generally classified in two ways.…”

“…In these materials two kinds of structures exist; b-CD crosslinked by epichlorohydrin and polymerized epichlorohydrin. In order to confirm this assumption, Crini et al investigated the structure of these insoluble polymers by solid state 13 C nuclear magnetic resonance techniques such as cross polarization magic angle spinning with dipolar decoupling (CP/MAS) and high resolution magic angle spinning (HRMAS) [40,184]. The two components were found and analyzed in terms of relaxation parameters such as 13 C spin lattice relaxation (T1) and 1 H spin lattice relaxation in the rotating frame (T1q).…”

“…The complexation phenomenon has been exploited for many separation techniques [41 -48], including high performance liquid chromatography (HPLC) [43,44], gas chromatography (GC) [43,45], capillary electrophoresis (CE) [39,48], micellar electrokinetic chromatography (MEKC) [40], thin-layer chromatography (TLC) [42], and micro-extraction [6 -8].…”