Raw matrix-assisted DOSY data

Raw matrix-assisted DOSY data, in Bruker Topspin forma

Matrix-assisted diffusion-ordered spectroscopy: choosing a matrix

Diffusion‐ordered spectroscopy (DOSY) is an important technique for separating the NMR signals of the components in a mixture, and relies on differences in diffusion coefficient. Standard DOSY experiments therefore struggle when the components of a mixture are of similar size, and hence diffuse at similar rates. Fortunately, the diffusion coefficients of solutes can be manipulated by changing the matrix in which they diffuse, using matrix components that interact differentially with them, a technique known as matrix‐assisted DOSY. In the present investigation, we evaluate the performance of a number of new, previously used, and mixed matrices with an informative test mixture: the three positional isomers of dihydroxybenzene. The aim of this work is to present the matrix‐assisted DOSY user with information about the potential utility of a set of matrices (and combinations of matrices), including ionic and non‐ionic surfactants, complexing agents, polymers, and mixed solvents. A variety of matrices improved the diffusion resolution of the signals of the test system, with the best separation achieved by mixed micelles of sodium dodecyl sulfate and cetyl trimethylammonium bromide. The use of mixed matrices offers great potential for the analyst to tailor the matrix to a particular sample under study. © 2016 The Authors Magnetic Resonance in Chemistry Published by John Wiley & Sons, Ltd

Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

Brij surfactant micelles in mixed solvent systems aid resolution of natural product NMR signals in diffusion-ordered spectroscopy.</p

Constituintes químicos voláteis e não-voláteis de Moringa oleifera Lam., Moringaceae

O estudo fitoquímico do extrato etanólico das folhas de Moringa oleifera Lam., Moringaceae, resultou no isolamento dos derivados benzilnitrilas niazirina, niazirinina e 4-hidroxifenil-acetonitrila, enquanto que das cascas dos frutos somente o octacosano foi obtido. Os óleos essenciais das folhas, flores e frutos foram analisados por cromatografia gasosa acoplada a espectrometria de massa. Os constituintes principais identificados foram: fitol (21,6%) e timol (9,6%) nas folhas, octadecano (27,4%) e ácido hexadecanóico (18,4%) nas flores e docosano (32,7%) e tetracosano (24,0%) nos frutos. As estruturas dos compostos isolados foram identificadas a partir de técnicas espectroscópicas (RMN, IV e EM). A 4-hidroxifenil-acetonitrila está sendo citada pela primeira vez para o gênero Moringa e os óleos essenciais das flores e frutos estão sendo citados pela primeira vez para a espécie M. oleifera

Flavonoides e terpenoides de Croton muscicarpa (Euphorbiaceae)

A new sesquiterpene and twelve known compounds comprising eight flavonoids and four terpenoids, were isolated from the leaves, stems, roots and exudate of Croton muscicarpa Müll. Arg.. Their structures were identified as the terpenoids 6α-methoxy-cyperene, dammaradienol, squalene, acetyl aleuritolic acid and spathulenol, and as the flavonoids retusin, 3,7,4'-trimethoxy kaempferol, ombuine, pachipodol, kaempferol, casticin, 5-hydroxy-3,6,7,4'-tetramethoxyflavone and artemetin. All isolated compounds were characterized based on IR, MS, ¹H and 13C NMR, including 2D analyses (COSY, HSQC, HMBC, NOESY) and comparison with data from the literature