Variations in the chemical structure and Carbon-13 natural abundance in water-stable macro- and microaggregates in Haplic Chernozem under the contrasting land use variants.

Water-stable macro- (WSAma) and free microaggregates (WSAmi) were isolated from the 2-1 mm air-dry macroaggregates from the surface horizons of Haplic Chernozem in contrasting variants of land use: the steppe and the bare fallow. The 13C NMR data and the 13C natural abundance of the Occluded organic matter (OM) (LFoc) and Clay within WSAs in the steppe obviously indicate a lower degree of microbiological processing of OM within WSAmi as compared with WSAma. This is reflected in lower degrees of decomposition (DI) and aromaticity (ARI) of OM and the C/N ratio, as well as lower 13C enrichment. This implies that the "labile" part of OM within WSAmi (LFoc and Clay, which are components of microaggregates within water-stable aggregates (mWSAs)) is more physically protected compared to that within WSAma. However, the heavier total δ13C signature of OM within WSAmi indicates its greater degree of microbiological processing compared to that within WSAma. This seems contrary to the concept of greater physical protection of OM within microaggregates as compared to macroaggregates. It was revealed that the heavier total δ13C signature of OM within WSAmi (greater degree of microbiological processing) is determined by the "oldest" OM located in the inter-aggregate space of WSAs, which is concentrated in the Residue fraction (Res). Due to its quantitative dominance, the Residue fraction is crucial for the total δ13C signature of WSAs. Negative changes in the quality of OM under the long-term bare fallow (52-yr) were reflected in a sharp increase in the integral indices of the chemical structure (DI, ARI), as well as the hydrophobicity index (HI) in all studied OM pools. It was accompanied by their 13C enrichment in the bare fallow compared to the steppe. Free microaggregates (WSAmi) are fragments of disintegrated macroaggregates (WSAma). We found no evidence of their formation within macroaggregates.

The detection, purity and structural properties of partially soluble mushroom and cereal ß-D-glucans: A solid-state NMR study.

ß-D-glucans are proposed to have many health benefits. It is therefore important to have methods which can distinguish these from other carbohydrates present in natural products, as well as giving glucan content and structural information. Correlations between features in the CP/MAS spectra of ß-D-glucans and enzyme assay determined ß-D-glucan content were generally found to be poor. The ß-D-glucan in dry and hydrated forms of the mushroom Ganoderma lucidum was investigated in detail by spectral peak fitting to the anomeric carbon C1 region in CP/MAS NMR spectra. Hydrated samples gave spectra with enhanced resolution and suggested that a clear distinction between ß-D-glucans and other carbohydrates could be possible in the anomeric carbon C1 region. Chemical shift values for a range of carbohydrate polymers, which can be found alongside ß-D-glucans, as well as the values for various linkages are given. Contamination by other carbohydrates and buffer salts is discussed.

Sequential natural deep eutectic solvent pretreatments of apple pomace: A novel way to promote water extraction of pectin and to tailor its main structural domains.

To establish a "green" biorefinery extraction of apple pomace pectin, a sequential pretreatment with three natural deep eutectic solvents (NADES, choline chloride (CC): glycerol (G); CC: lactic acid (LA); potassium carbonate (K): G) was used prior to hot water extraction. A synergistic effect of CC:G and CC:LA pretreatments was observed and led to the highest recovery of pectin. The sequential NADES/water extraction process also provided a mean to tailor pectin main structure. It was explained as resulting from ion exchange and individual NADES components effects. The 13C solid state NMR T1ρH and THH parameters indicated a reorganization of cellulose in the residues following extraction of pectin, notably after alkaline K:G pretreatment/water extraction. Hence, sequential NADES pretreatments/water extraction represents a "green" alternative to mild mineral acid to extract pectin and to tailor its main structures, while the residual pomace can be further sources of valuable compounds and polymers.

Synthesis and Characterization of New 3-(4-Arylpiperazin-1-yl)-2-hydroxypropyl 4-Propoxybenzoates and Their Hydrochloride Salts.

Five new 3-(4-arylpiperazin-1-yl)-2-hydroxypropyl 4-propoxybenzoates were designed and synthesized as potential dual antihypertensive agents. The compounds were prepared as free bases and subsequently transformed to hydrochloride salts. The position of protonation of nitrogen atoms in the piperazine ring of hydrochloride salts was determined by means of (13)C-CP/MAS and (15)N-CP/MAS NMR and IR spectroscopy. Using these solid-state analytical techniques, it was found that both nitrogen atoms were protonated when excess hydrogen chloride was used for preparation of salts. On the other hand, when the equimolar amount of hydrogen chloride was used, piperazine nitrogen substituted by aryl was protonated.

Supramolecular self-organisation and conformational isomerism of a binuclear O,O'-dipropyl dithiophosphate gold(I) complex, [Au2{S2P(OC3H7)2}2]: Synthesis, (13)C and (31)P CP/MAS NMR spectroscopy, single-crystal X-ray diffraction study and thermal behaviour.

Crystalline one-dimensional polymeric catena-poly[bis(µ2-O,O'-dipropyldithiophosphato-S,S')digold(I)] (Au-Au) (1) was prepared and studied using (13)C and (31)P CP/MAS NMR spectroscopy and single-crystal X-ray diffraction. To elucidate the structural function of Dtph ligands in crystalline gold(I) O,O'-dipropyl dithiophosphate, the chemical shift anisotropy parameters (δaniso and η) were calculated from spinning sideband manifolds in (31)P MAS NMR spectra. A novel structure of the gold(I) compound comprises two isomeric, non-centrosymmetric binuclear molecules of [Au2{S2P(OC3H7)2}2] (isomers 'A' and 'B'), whose four Dtph groups display structural inequivalence. In each isomeric binuclear molecule of 1, a pair of µ2-bridging dipropyl Dtph ligands almost symmetrically links two neighbouring gold atoms, forming an extensive eight-membered metallocycle [Au2S4P2], while the intramolecular aurophilic Au⋯Au bond additionally stabilises this central cyclic moiety. At the supramolecular level of complex 1, intermolecular aurophilic Au⋯Au bonds yield almost linear infinite polymeric chains (⋯'A'⋯'B'⋯'A'⋯'B'⋯)n. The thermal behaviour of this compound was studied by the simultaneous thermal analysis (STA) technique (a combination of TG and DSC) under an argon atmosphere.