Solid-Phase Extraction at High pH as a Promising Tool for Targeted Isolation of Biologically Active Fractions of Humic Acids.

A search for novel sources of biologically active compounds is at the top of the agenda for biomedical technologies. Natural humic substances (HSs) contain a large variety of different chemotypes, such as condensed tannins, hydrolyzable tannins, terpenoids, lignins, etc. The goal of this work was to develop an efficient separation technique based on solid-phase extraction (SPE) for the isolation of narrow fractions of HS with higher biological activity compared to the initial material.

1,2-Bis(triazolyl)tetraphenyldigermanes: Synthesis, Structure and Properties.

Using the [3+2] cycloaddition reaction of [HC≡C-GePh -] (1) and a number of RCH N , this work described the synthesis of a series of novel heterocyclic digermanes, bitriazoles [1,4-C HN (CH R)GePh -] , 2-12 (R=Ph, p-Tol, p-C H NMe , p-C H OMe, p-C H Br, m-C H NO , 2-Naphth, CH -p-OC H CHO, CH -p-OC H COOMe, CH P(O)(OEt) , COOEt), difficult to produce by other methods. The structural peculiarities of these compounds were studied in detail by NMR spectroscopy and by XRD analysis (for 6, 9 and 10). The properties of 1-12 were studied by UV/vis and luminescence emission spectroscopy, electrochemistry and DFT calculations, indicating an effective conjugation in their molecules.

Structural Motifs in Aryl Organogermanium Ge-O Derivatives for Material Design.

The aim of this work was to understand the main structural features and ways of formation of Ge-O bonds in organogermanium compounds under the conditions of ArGeHal (Hal = halide) hydrolysis. The structural types of these compounds were considered, providing 11 blocks (-). The molecular structures of the novel compounds [(-FCH)Ge]O (), [(-FCCH)Ge]O (), and -[(-FCCH)GeO] () were studied through XRD (X-ray diffraction) analysis.

Germanium Complexes with Tridentate Ligands: O-H Bond Activation Control According to DFT Calculations.

Polydentate ligands are used for thermodynamic stabilization of tetrylenes-low-valent derivatives of Group 14 elements (E = Si, Ge, Sn, Pb). This work shows by DFT calculations how the structure (the presence or absence of substituents) and type (alcoholic, Alk, or phenolic, Ar) of tridentate ligands 2,6-pyridinobis(1,2-ethanols) []H and 2,6-pyridinobis(1,2-phenols) []H (R = H, Me) may affect the reactivity or stabilization of tetrylene, indicating the unprecedented behavior of Main Group elements. This enables the unique control of the type of the occurring reaction.

Formation of Azaphilone Pigments and Monasnicotinic Acid by the Fungus .

Due to the ever-increasing demand for healthy and safe food, much attention has been gained by natural food colorants. This study showed the culture fluid extract of the fungus VKM F-906 to contain red pigment and monasnicotinic acid (MNA) in predominant amounts. The structure of the pigment corresponded to -cavernamine (red pigment, RP).

Oligoorganogermanes: Interplay between Aryl and Trimethylsilyl Substituents.

Derivatives of main group elements containing element-element bonds are characterized by unique properties due to σ-conjugation, which is an attractive subject for investigation. A novel series of digermanes, ArGe-Ge(SiMe), containing aryl (Ar = -CHMe (), -CHF (), CF ()) and trimethylsilyl substituents, was synthesized by the reaction of germyl potassium salt, [(MeSi)GeK*THF], with triarylchlorogermanes, ArGeCl. The optical and electronic properties of such substituted oligoorganogermanes were investigated spectroscopically by UV/vis absorption spectroscopy and theoretically by DFT calculations.

Optical Properties of Soil Dissolved Organic Matter Are Related to Acidic Functions of Its Components as Revealed by Fractionation, Selective Deuteromethylation, and Ultrahigh Resolution Mass Spectrometry.

The goal of this study was to establish a relationship between the optical properties of soil dissolved organic matter (DOM) and acidic functions carried out by its individual constituents. We obtained 12 fractions of DOM samples using sequential solid phase extraction on nonionic sorbent at steadily lowered pH values: 7, 5, 3, 2, which correspond to low bounds of p values of phenols, aliphatic, and aromatic carboxylic acids, and ketoacids. The structural studies were conducted with the use of NMR and selective deuteromethylation of isolated fractions coupled to ultrahigh resolution mass spectrometry.

Austalides V and W, new meroterpenoids from the fungus Aspergillus ustus and their antitumor activities.

Two new austalide meroterpenoids, named austalides V and W (1 and 2), were isolated from the fungus Aspergillus ustus VKM F-4692. Their structures were elucidated by extensive spectroscopic analysis and by comparison with related known compounds. The main structural feature of both compounds is a tetrahydrofuranyl ring (G), a structural fragment, first found in austalides.

Hypercoordinated Oligosilanes Based on Aminotrisphenols.

The hypercoordinated silicon chlorides ClSi[(-OCH)N] () and ClSi[(OCHMeCH)N] () were used for the synthesis of catenated derivatives (MeSi)SiSi[(-OCH)N] (), (MeSi)SiSiMeSiMeSi(SiMe)Si[(-OCH)N] (), and (MeSi)SiSi[(OCHMeCH)N] () in reactions with (MeSi)SiK·THF () or (MeSi)SiK·[18-crown-6] (). It was found that the nature of the (MeSi)SiK solvate determines the product of interaction, resulting in the formation of (MeSi)Si(CH)OSi[(OCHMeCH)N] () or . Compounds obtained were characterized using multinuclear NMR and UV-vis spectroscopy and mass spectrometry.

Oligothienyl catenated germanes and silanes: synthesis, structure, and properties.

The synthesis of two new groups of oligothienyl catenated silanes and germanes, Me5M2Thn (1a-b), Me5M2ThnM2Me5 (2a-c) (terminal), and ThnM2Me4Thn (3a-d) (internal) (M = Si, Ge; n = 2, 3; Th = 2- or 2,5-thienyl), is reported. The study of their structural parameters as well as of their spectral (NMR), electrochemical (CV) and optical (UV/vis absorbance, luminescence) properties has been performed in detail; in addition, the unexpected compound [Th2Si2Me4Th]2 (3a') is also studied. Theoretical investigations have been performed for model compounds in order to establish structure-property relationships.

Synthesis of carboxylated styrene polymer for internal calibration of Fourier transform ion cyclotron resonance mass-spectrometry of humic substances.

We report synthesis and application of the novel carboxylated styrene for internal calibration of Fourier transform ion cyclotron resonance mass-spectra of humic substances. The calibrant was synthesized in five steps from acetylsalicylic acid (aspirin) followed by spontaneous polymerization of vinyl salicylic acid. Aromatic nature of the prepared polymer enabled its simultaneous analysis in the presence of the Suwannee River fulvic acid without using dual-spray approach.

Molecular Oligogermanes and Related Compounds: Structure, Optical and Semiconductor Properties.

The optical (UV/Vis absorbance, fluorescence in the solid state and in solution) and semiconducting properties of a number of di- and trigermanes as well as related silicon- and tin-containing germanes, 1-6 ((p-Tol) GeGeMe (1), Ph SnGe(SiMe ) (2), (C F ) GeGePh (3), (p-Tol) GeSiMe SiMe (4), (p-Tol) GeGeMe Ge(p-Tol) (5), (p-Tol) GeSiMe SiMe Ge(p-Tol) (6)) were investigated. Molecular structures of 5 and 6 were studied by X-ray diffraction analysis. All compounds displayed luminescence properties.

Enumeration of carboxyl groups carried on individual components of humic systems using deuteromethylation and Fourier transform mass spectrometry.

Here, we report a novel approach to enumeration of carboxylic groups carried by individual molecules of humic substances using selective chemical modification and isotopic labeling (deuteromethylation) and high-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FTICR MS). Esterification was conducted with a use of thionyl chloride-deuteromethanol reagent under mild conditions to avoid transesterification. The deuteromethylated products were subjected to solid phase extraction using PPL Bond Elute cartridges prior to FTICR MS analysis.

Crystal structure of 2,6-bis-(2-hy-droxy-5-methyl-phen-yl)-4-phenyl-pyridinium bromide di-chloro-methane hemisolvate hemihydrate.

The asymmetric unit in the structure of the title compound, C25H22NO2 (+)·Br (-)·0.5CH2Cl2·0.5H2O, comprises two pseudosymmetry-related cations, two bromide anions, a di-chloro-methane molecule and a water mol-ecule of solvation.

Crystal structure of 4,8-di-tert-butyl-6,6-di-chloro-13-ethyl-2,10-dimethyl-13,14-di-hydro-12H-dibenzo[d,i][1,3,7,2]dioxaza-silecine toluene 0.25-solvate.

The coordination polyhedron at the silicon atom in the title compound, C26H37Cl2NO2Si·0.25C7H8, is typical for penta-coordinated silicon derivatives and represents a slightly distorted trigonal bipyramid with an N atom and a Cl atom in the apical positions and the two O atoms and the other Cl atom occupying the equatorial sites. There are two independent mol-ecules in the asymmetric unit.

Crystal structure of (tert-butyl-dimethyl-sil-yl)tri-phenyl-germane, Ph3Ge-SiMe2(t-Bu).

In the title compound, Ph3Ge-SiMe2(t-Bu) or C24H30GeSi, the Si and Ge atoms both possess a tetra-hedral coordination environment with C-E-C (E = Si, Ge) angles in the range 104.47 (5)-114.67 (5)°.

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP.

A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1-4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2-4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3-4b, were obtained by substitution of the Me group under the action of chlorinating agents.

Synthesis of model humic substances: a mechanistic study using controllable H/D exchange and Fourier transform ion cyclotron resonance mass spectrometry.

The products of the oxidative coupling of phenols are frequently used as synthetic analogues to natural humic substances (HS) for biomedical research. However, their molecular compositions and exact structures remain largely unknown. The objective of this study was to develop a novel approach for the molecular-level analysis of phenolic polymerisates that is capable of inventorying molecular constituents and resolving their distinct structural formulas.

Crystal structure of 2,2,3,3-tetra-methyl-1,1,1,4,4,4-hexa-phenyl-tetra-germane.

The mol-ecule of the title compound, C40H42Ge4, lies with its central Ge-Ge bond on an inversion centre giving rise to a zigzag backbone of four tetra-hedrally coordinated Ge atoms. The symmetrically independent Ge-Ge bonds are slightly shorter than in other organo-tetra-germanes whereas the Ge-CPh (Ph = phen-yl) and Ge-CMe (Me = meth-yl) distances have their usual values. In the crystal, (010) layers of Ph6Me4Ge4 mol-ecules with a parallel orientation of the Ge4 backbone exist, held together by van der Waals forces only.

Crystal structure of a mixed-valence μ-oxide Sn12 cluster.

The mixed-valence μ-oxide Sn12 cluster, deca-carbonyl-tetra-μ4-oxido-hexa-μ3-oxido-tetra-kis-[μ-2,2'-(pyridine-2,6-di-yl)bis(1,1-di-phenyl-ethano-lato)]deca-tin(II)ditin(IV)dimolyb-denum(O)(2 Mo-Sn) toluene hepta-solvate, [Mo2Sn12(C33H27NO2)4O10(CO)10]·7C7H8, has a crystallographically imposed inversion centre. The asymmetric unit also contains three and a half toluene solvent mol-ecules, one of which is disordered about a centre of symmetry. The complex mol-ecule comprises six distinct Sn atom species with four different coordination numbers, namely 3, 4, 5, and 6.

New oligogermane with a five coordinate germanium atom: the preparation of 1-germylgermatrane.

The first example of an oligogermane, N(CH2CH2O)3Ge-Ge(SiMe3)3 (1), containing a hypercoordinate germanium atom was prepared and characterized by various methods (NMR, UV/vis, and X-ray analysis). The electronic structure of compound 1 was investigated via DFT calculations.

{2,2'-[Ethane-1,2-diylbis(nitrilo-methan-yl-yl-idene)]diphenolato}(iso-propano-lato)aluminium di-chloro-methane hemisolvate.

In the title compound, [Al(C16H14N2O2)(C3H7O)]·0.5CH2Cl2, the salen complex is monomeric and the dichlormethane solvent mol-ecule lies on a crystallographic twofold axis. The central Al atom is fivefold coordinated and possesses a square-based pyramidal environment.

Di-μ-oxido-bis-({2,2'-[ethane-1,2-diylbis(nitrilo-methanylyl-idene)]diphenolato}titanium(IV)) chloro-form disolvate.

In the title compound, [Ti2(C16H14N2O2)2O2]·2CHCl3, the Ti(IV) atom in the centrosymmetric complex has a distorted octa-hedral N2O4 coordination environment and is linked via two μ2-oxido bridges into a dinuclear centrosymmetric com-plex, with a Ti⋯Ti separation of 2.7794 (8) Å. In the salen (N,N'-ethyl-enebis(salicyl-imine)) ligand, the two salicyl-imine units make a dihedral angle of 45.