NOESY-HSQC 3D-NMR and NOESY 2D-NMR techniques have been used on a 750 MHz spectrometer to study the chain conformations of different generation DAB dendrimers (poly[propylene imine] dendrimers) in chloroform and benzene solutions. The high-field multidimensional NMR techniques provided the chemical shift dispersion needed to resolve all of the unique resonances in the dendrimers. By studying the NOE interactions among dendritic chain protons, information about through space interactions between protons on different parts of the dendrimer chain is obtained, which is directly related to the conformation of the dendrimer. These experiments also give further proof of the chemical shift assignments obtained from the HMQC-TOCSY 2D and 3D NMR experiments. The concentration effects on chemical shifts have also been observed, revealing information about the interactions between solvent and different parts of dendrimer molecules. These studies clearly show for DAB dendrimers, that folded chain conformations can occur in nonpolar solvents such as benzene and extended chain conformations are predominant in polar solvents such as chloroform.

Anthocyanin constituents in black raspberries (Rubus occidentalis L.) were investigated by HPLC-DAD, and their involvement as potent, significant antioxidants in black raspberries was demonstrated by three common antioxidant assays (FRAP, DPPH, ABTS) in this study. Five anthocyanins were present in black raspberries: cyanidin 3-sambubioside, cyanidin 3-glucoside, cyanidin 3-xylosylrutinoside, cyanidin 3-rutinoside, and pelargonidin 3-rutinoside. Their identities and structures, with particular emphasis on cyanidin 3-xylosylrutinoside, were confirmed by NMR spectroscopy. Two of these anthocyanins, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside, predominated, comprising 24-40 and 49-58%, respectively, of the total anthocyanins in black raspberries. On the basis of both potency and concentration, cyanidin 3-rutinoside and cyanidin 3-xylosylrutinoside were found to be the significant contributors to the antioxidant systems of black raspberries. These findings indicate that these two anthocyanin compounds may function as the primary phenolic antioxidants in black raspberries. These two compounds exhibit potential biological activities that may be exploited in conjunction with other naturally occurring bioactive compounds in black raspberry fruit-based products used in clinical trials for the treatment of various types of cancer.

A series of poly(ethylene-co-vinyl acetate-co-carbon monoxide) terpolymer samples with varying monomer compositions were studied using a variety of one-and two-dimensional nuclear magnetic resonance (NMR) techniques at 750 MHz. Samples were characterized in deuterated 1,4-dichlocrobenzene-d 4 at high temperature (120°C) to overcome the signal loss and broadening due to T 2 relaxation. Identification of major triads formed due to the addition of the three monomers in different permutations was facilitated by the use of different 2D techniques such as gradient assisted heteronuclear single-quantum correlation (gHSQC), gradient selected heteronuclear multiple-bond correlation (gHMBC), and gradient assisted HSQC-TOCSY. Detection of unusual structures formed due to the addition of carbon monoxide to vinyl acetate or structures due to the inversion of vinyl acetate was also possible. Because of improved dispersion the study was not restricted to the triad level, but in some cases pentads could also be identified. Distinct resonances of chain ends and short-chain branches were also observed.

Herein are presented the 188.6 MHz 13C NMR spectra (corresponding to 750 MHz 1H resonance frequency) of a series of copolymers from ethylene and 1-octene monomers. These spectra permit the resolution of unique 13C resonances from hexyl chain branches. The 750 MHz high-temperature pulsed field gradient (PFG), heteronuclear multiple quantum correlation (HMQC), and heteronuclear multiple-bond correlation (HMBC) two-dimensional (2D) NMR spectra of ethylene/1-octene copolymers are also presented. Data are presented from a new probe capable of performing high-temperature PFG coherence selection experiments at temperatures typical of those used in many polymer analyses. The performance of this probe is illustrated with PFG−HMQC and PFG−HMBC spectra of copolymers from ethylene/1-octene at 120 °C. Detailed unequivocal proof of the resonance assignments for poly(ethylene-co-1-octene) is reported. The 2D NMR spectra were used to confirm 1H and 13C chemical shift assignments previously determined by empirical methods. Quantitative analyses of the ethylene/1-octene copolymers were also performed.