13C NMR and ESR Characterization of Humic Substances Isolated from Soils of Two Siberian Arctic Islands

International Journal of Ecology ◽

10.1155/2015/390591 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 9

Author(s):

E. Abakumov ◽

E. Lodygin ◽

V. Tomashunas

Keyword(s):

Fulvic Acids ◽

The Arctic ◽

Initial Stage ◽

Degree Of Aromaticity ◽

Siberian Arctic ◽

Temperate Soils ◽

Polar Soils ◽

C Nmr ◽

Humus Horizons

Humic acids (HAs) and fulvic acids (FAs) of two Polar soils were investigated by13C NMR and ESR spectroscopies, investigating the degree of humification and the molecular structure. One soil, from Bolshoi Lyakhovsky Island, contains two humus horizons: modern and buried. The other soil, from Wrangel Island, had only one modern humus horizon. The HAs and FAs of the two soils investigated show essential differences. The HAs show fewer oxygen-containing groups in comparison with the FAs, whereas the degree of aromaticity is two or three times higher in the HAs. The13C NMR data also show that HAs are very different from FAs in terms of their molecular composition and hydrophobicity. Humification in the Arctic is limited by the very low content of lignin-derived compounds, due to the restricted vascular flora. As a result, the HAs, isolated from Polar soils, are more similar to the corresponding FAs than to the typical HAs of temperate soils. This was confirmed by ESR data, which show similar levels of free radical concentration for HAs and FAs and are related to the low level of aromaticity of both materials investigated. Apparently, the humification process in the soils of Polar Arctic deserts is in an initial stage.

Download Full-text

Characterization of humic substances extracted from Canadian lake sediments

Canadian Journal of Chemistry ◽

10.1139/v97-003 ◽

1997 ◽

Vol 75 (1) ◽

pp. 14-27 ◽

Cited By ~ 47

Author(s):

Nelson Belzile ◽

Helen A. Joly ◽

Hongbo Li

Keyword(s):

Lake Sediments ◽

Humic Substances ◽

Chemical Nature ◽

Chemical Properties ◽

Fulvic Acids ◽

Humic And Fulvic Acids ◽

Similar Chemical ◽

Low Degree ◽

C Nmr

Humic substances (HS) were extracted from the sediments of four Sudbury area lakes, namely, Tilton, Clearwater, Silver, and Ramsey Lakes, with the aid of 0.1 M Na4P2O7 and 0.5 M NaOH solutions. The HS (humic and fulvic acids) were purified and characterized using the methods of elemental analysis, visible spectroscopy (E4/E6 ratio), FTIR, and solid-state 13C CPMAS NMR. A substantial amount of information with regard to the composition and chemical nature of lake sediment HS was obtained. The results obtained for the Sudbury area lake sediments were compared with one another and with HS from other sources, such as soils. The elemental composition, atomic ratios, E4/E6 ratios, and FTIR and NMR features of the samples from the above lakes were found to be nearly identical, suggesting that HS formed in the Sudbury area have similar chemical properties. Compared with soil HS, the Sudbury lake sediments HS have undergone a low degree of aromatic condensation and are considerably more aliphatic in nature. Keywords: humic substances, characterization, lake sediments, extraction, 13C NMR.

Download Full-text

Characterization of the Initial Stage of Discharges between Micro-gap in Liquid using Optical Measurement

IEEJ Transactions on Fundamentals and Materials ◽

10.1541/ieejfms.130.313 ◽

2010 ◽

Vol 130 (4) ◽

pp. 313-318

Author(s):

Makoto Kanemaru ◽

Shohei Sorimachi ◽

Shinji Ibuka ◽

Shozo Ishii

Keyword(s):

Optical Measurement ◽

Initial Stage

Download Full-text

Characterization of Soil Organic Matter Individual Fractions (Fulvic Acids, Humic Acids, and Humins) by Spectroscopic and Electrochemical Techniques in Agricultural Soils

Agronomy ◽

10.3390/agronomy11061067 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1067

Author(s):

Aleksandra Ukalska-Jaruga ◽

Romualda Bejger ◽

Guillaume Debaene ◽

Bożena Smreczak

Keyword(s):

Molecular Weight ◽

Organic Matter ◽

Soil Organic Matter ◽

Humic Substances ◽

Humic Acids ◽

Agricultural Soils ◽

Fulvic Acids ◽

Sorption Properties ◽

Aliphatic Chains

The objective of this paper was to investigate the molecular characterization of soil organic matter fractions (humic substances (HS): fulvic acids-FAs, humic acids-HAs, and humins-HNs), which are the most reactive soil components. A wide spectrum of spectroscopic (UV–VIS and VIS–nearIR), as well as electrochemical (zeta potential, particle size diameter, and polydispersity index), methods were applied to find the relevant differences in the behavior, formation, composition, and sorption properties of HS fractions derived from various soils. Soil material (n = 30) used for the study were sampled from the surface layer (0–30 cm) of agricultural soils. FAs and HAs were isolated by sequential extraction in alkaline and acidic solutions, according to the International Humic Substances Society method, while HNs was determined in the soil residue (after FAs and HAs extraction) by mineral fraction digestion using a 0.1M HCL/0.3M HF mixture and DMSO. Our study showed that significant differences in the molecular structures of FAs, Has, and HNs occurred. Optical analysis confirmed the lower molecular weight of FAs with high amount of lignin-like compounds and the higher weighted aliphatic–aromatic structure of HAs. The HNs were characterized by a very pronounced and strong condensed structure associated with the highest molecular weight. HAs and HNs molecules exhibited an abundance of acidic, phenolic, and amine functional groups at the aromatic ring and aliphatic chains, while FAs mainly showed the presence of methyl, methylene, ethenyl, and carboxyl reactive groups. HS was characterized by high polydispersity related with their structure. FAs were characterized by ellipsoidal shape as being associated to the long aliphatic chains, while HAs and HNs revealed a smaller particle diameter and a more spherical shape caused by the higher intermolecular forcing between the particles. The observed trends directly indicate that individual HS fractions differ in behavior, formation, composition, and sorption properties, which reflects their binding potential to other molecules depending on soil properties resulting from their type. The determined properties of individual HS fractions are presented as averaged characteristics over the examined soils with different physico-chemical properties.

Download Full-text

In-Situ Characterization of Growth and Intermixing at a Heteroepitaxial Interface: Fe on Au(001)

MRS Proceedings ◽

10.1557/proc-318-13 ◽

1993 ◽

Vol 318 ◽

Author(s):

Q. Jiang ◽

A. Chan ◽

Y.-L. He ◽

G.-C. Wang

Keyword(s):

Elevated Temperatures ◽

Chemical Elements ◽

Background Intensity ◽

In Situ Characterization ◽

Initial Stage ◽

Monolayer Growth ◽

Low Energy Electron ◽

Energy Dependent

ABSTRACTThe growth and chemical intermixing of submonolayer and a few monolayer thick Fe films on a Au(001) surface was studied by High Resolution Low Energy Electron Diffraction (HRLEED) technique. Through the analysis of the energy dependent angular profiles as a function of time, we obtained the distribution of islands and distribution of spacings during submonolayer growth. The interference of electron waves from different chemical elements in terraces at different heights in the surface contributes to the background intensity and broadening in the angular profiles of diffraction beams. A subsurface Fe capped by Au islands as a result of atomic place exchange was observed at the initial stage of monolayer growth. From the energy dependent angular profiles as a function of temperature, we determine the quantitative change of inhomogeneity length (∼20 Å) at the interface of ultrathin films at elevated temperatures due to intermixing.

Download Full-text

The metal reductase activity of some multiheme cytochromes c: NMR structural characterization of the reduction of chromium(VI) to chromium(III) by cytochrome c7

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.152290999 ◽

2002 ◽

Vol 99 (15) ◽

pp. 9750-9754 ◽

Cited By ~ 32

Author(s):

M. Assfalg ◽

I. Bertini ◽

M. Bruschi ◽

C. Michel ◽

P. Turano

Keyword(s):

Structural Characterization ◽

Reductase Activity ◽

Chromium Vi ◽

Cytochromes C ◽

Cytochrome C7 ◽

C Nmr

Download Full-text

Electrochemical and binding properties of a meso-tetra(4-pyridyl)porphyrinatozinc supermolecule containing four μ3-oxo-triruthenium acetate clusters

Journal of Porphyrins and Phthalocyanines ◽

10.1002/1099-1409(200012)4:8<727::aid-jpp290>3.0.co;2-6 ◽

2000 ◽

Vol 04 (08) ◽

pp. 727-735 ◽

Cited By ~ 15

Author(s):

SERGIO DOVIDAUSKAS ◽

KOITI ARAKIA ◽

HENRIQUE E. TOMA

Keyword(s):

Equilibrium Constants ◽

Zinc Ion ◽

Porphyrin Ring ◽

Electronic Density ◽

Axial Coordination ◽

Spectrophotometric Titrations ◽

Regular Increase ◽

Calculated Equilibrium ◽

C Nmr

The synthesis and characterization of a zinc meso-tetra(4-pyridyl)porphyrin containing four coordinated μ3-oxo-triruthenium acetate cluster complexes, ZnTCP , are reported. The coordination of four ruthenium acetate clusters to the zinc porphyrin has been confirmed by 1 H and 13 C NMR spectroscopy, including COSY and HETCOR bidimensional correlation techniques. Cyclic voltammetry and spectroelectrochemistry studies have revealed the presence of seven redox processes in the −1.5 to 2.5 V range, four of them attributed to cluster-centered ( Ru IV,IV,III/ Ru IV,III,III/ Ru III,III,III/ Ru III,III,II/ Ru III,II,II) and three to porphyrin ring-centered ( ZnP +/ ZnP / ZnP .−/ ZnP 2−) redox reactions. The axial coordination reaction has been monitored by spectrophotometric titrations in dichloromethane and acetonitrile, in the 380–480 nm range, using pyridine, imidazole, water and acetonitrile as ligands. The influence of the peripheral ruthenium complexes on the electronic properties of the porphyrin ring has been assayed by measuring the axial coordination properties of the zinc ion. The calculated equilibrium constants for axial coordination of pyridine and imidazole to ZnTCP in dichloromethane are respectively one and two orders of magnitude higher than for meso-tetraphenylporphyrinatozinc, showing a regular increase as a function of the basicity of the ligands. The results have demonstrated that the Ru (III,III,III) species act as electron-withdrawing groups, decreasing significantly the electronic density on the porphyrin ring.

Download Full-text

Les oxazolines-4 précurseurs de sels d'iminium fonctionnels. Ouverture en milieu anhydre de ces hétérocycles par des acides protoniques: obtention de sels d'iminium fonctionnels, étude de leur structure

Canadian Journal of Chemistry ◽

10.1139/v79-467 ◽

1979 ◽

Vol 57 (21) ◽

pp. 2876-2884 ◽

Cited By ~ 3

Author(s):

Michel Vaultier ◽

Gurbachan Mullick ◽

Robert Carrié

Keyword(s):

Hydrogen Atom ◽

Room Temperature ◽

Iminium Salts ◽

C Nmr

The protonation of 4-oxazolines with protic acids in anhydrous medium, both at low or at room temperature, generally leads to acyclic functional iminium salts. In those cases where the oxazoline ring bears a hydrogen atom in the four position, two diastereoisomeric cyclic iminium salts are obtained. The conditions for preparation of these salts along with the characterization of their structures were determined by the aid of 1H and 13C nmr.

Download Full-text

Influence of Post-Treatment with Methanol Vapor on the Properties of SF/P(LLA-CL) Nanofibrous Scaffolds

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.236-238.2221 ◽

2011 ◽

Vol 236-238 ◽

pp. 2221-2224

Author(s):

Kui Hua Zhang ◽

Xiu Mei Mo

Keyword(s):

Electrospun Nanofibers ◽

Random Coil ◽

Methanol Vapor ◽

Nanofibrous Scaffolds ◽

Nanofibrous Structure ◽

Α Helix ◽

Β Sheet ◽

Ideal Method ◽

C Nmr

In order to improve water-resistant ability silk fibroin (SF) and SF/P(LLA-CL) blended nanofibrous scaffolds for tissue engineering applications, methanol vapor were used to treat electrospun nanofibers. SEM indicated SF and SF/ P(LLA-CL) scaffolds maintained nanofibrous structure after treated with methanol vapor and possessed good water-resistant ability. Characterization of 13C NMR clarified methanol vapor induced SF conformation from random coil or α- helix to β-sheet. Moreover, treated SF/ P (LLA-CL) nanofibrous scaffolds still kept good mechanical properties. Methanol vapor could be ideal method to treat SF and SF/ P(LLA-CL) nanofibrous scaffolds for biomedical applications.

Download Full-text

Characterization of New Inorganic- Organic Hybrid Compounds: (C6H10N2).Cl2 (I), [C6H10N2]2ZnCl4 (II): Crystal Structure, Hirschfield Surface, IR and NMR spectroscopy Analysis.

10.21203/rs.3.rs-803292/v1 ◽

2021 ◽

Author(s):

nejeh hannachi ◽

faouzi hlel

Keyword(s):

Nmr Spectroscopy ◽

Three Dimensional ◽

X Ray Diffraction ◽

Spectroscopy Analysis ◽

Absorption Bands ◽

Monoclinic System ◽

Xrd Pattern ◽

Organic Hybrid ◽

C Nmr

Abstract Two new organic-inorganic hybrid materials, (C6H10N2).Cl2 (I) and [C6H10N2]2ZnCl4 (II), have been synthesized by hydrothermal method and characterized by single-crystal X-ray diffraction and XRD pattern investigations. These two compounds are crystallized in the monoclinic system; C2/c space group. In the both structures, the anionic-cationic entities are interconnected by hydrogen bonding contacts and p-p Interaction forming three-dimensional networks. Intermolecular interactions were investigated by Hirshfeld surfaces and the contacts of the four different chloride atoms in (II) were compared. The vibrational absorption bands were identified by infrared spectroscopy. These compounds were also investigated by solid state 13C NMR spectroscopy.

Download Full-text