Synthesis,Crystal Structures,and Spectroscopic Properties of Novel Gadolinium and Erbium Triphenylsiloxide Coordination Entities

In alkali metal and lanthanide coordination chemistry, triphenylsiloxides seem to be unduly underappreciated ligands. This is as surprising as that such substituents play a crucial role, among others, in stabilizing rare oxidation states of lanthanide ions, taking a part of intramolecular and molecular interactions stabilizing metal-oxygen cores and many others. This paper reports the synthesis and characterization of new lithium [Li₄(OSiPh₃)₄(THF)₂] (1), and sodium [Na₄(OSiPh₃)₄] (2) species, which were later used in obtaining novel gadolinium [Gd(OSiPh₃)₃(THF)₃]·THF (3), and erbium [Er(OSiPh₃)₃(THF)₃]·THF (4) configuration, it can result in res were determined for all 1–4 compounds, and in addition, IR, Raman, absorption spectroscopy studies were conducted for 3 and 4 lanthanide compounds. Furthermore, direct current (dc) variable-temperature magnetic susceptibility measurements on polycrystalline samples of 3 and 4 were carried out in the temperature range 1.8–300 K. The 3 shows behavior characteristics for the paramagnetism of the Gd³⁺ ion. In contrast, the magnetic properties of 4 are dominated by the crystal field effect on the Er³⁺ ion, masking the magnetic interaction between magnetic centers of neighboring molecules.     

The properties of the interfacial antimony cell and its application in potentiometric titrations of alkaloids in non-conducting solutions

The behaviour of an interfacial antimony device in potentiometric titrations in non-conducting solutions is described. In tests of the device, various alkaloids were titrated with organic acids, p-toluenesulphonic acid being the most satisfactory. The non-conducting media examined were chloroform, ligroin, benzene and carbon tetrachloride. In all cases, solutions of the titrant and the sample were prepared in the same organic solvent. Alkaloids in the range 10^?3–10^?4 M could usually be titrated with a precision of about 2%.     

Two-dimensional miscibility studies--the analysis of interaction between long-chain alcohols and semifluorinated alkanes

This work presents the results of phase behavior studies of two-dimensional (2D) binary systems involving semifluorinated alkanes (SFAs) and fatty alcohols. Four different SFAs were selected for investigations: (i) with a short and branched perfluorinated moiety (iF3H20), (ii) with a short and normal perfluorinated chain (F4H20), (iii) with a long and branched perfluorinated fragment (iF9H20), and (iv) with a long and normal perfluorinated group (F10H20). Two alcohols were selected to mix with the above-mentioned SFAs: tetradecanol and docosanol. The measurements were based on surface pressure/area isotherms in addition to Brewster angle microscope (BAM) imaging. Dependencies of the collapse surface pressure and the compression modulus vs the monolayer composition together with the excess free energy of mixing values, complemented with BAM images, enabled us to draw some general conclusions regarding the phase behavior of the investigated mixed systems. Generally, it has been noticed that the addition of docosanol into an SFA monolayer exerts a condensing effect, contrary to tetradecanol. Moreover, SFAs with a long perfluorinated segment mix to a larger extent with alcohols as compared to their analogues having a short perfluorinated moiety. The resultant phase diagrams for all the investigated eight mixtures are presented and discussed.     

Single crystal diffraction under high pressure with synchrotron radiation and a diamond anvil cell

Abstract

A single crystal study on AlPO₄ was performed at 2.90 GPa with synchrotron radiation with a wavelength of only 0.54 ?. The diffracted intensity was high enough to measure even weak reflections with sufficient counting statistics. However, the search for the reflections needed to setup the orientation matrix required a lot of beamtime. A feasibility study was carried out using a proportional area counter to reduce this search time. The results demonstrate that such counters can considerably reduce the time needed for the orientation of the crystal and the data collection.

Presented at the IUCr Workshop on ‘Synchrotron Radiation Instrumentation for High Pressure Crystallography’. Daresbury Laboratory 20-21 July 1991     

Algorithms generating images of attractors of generalized iterated function systems

The paper is devoted to searching algorithms which will allow to generate images of attractors of generalized iterated function systems (GIFS in short), which are certain generalization of classical iterated function systems, defined by Mihail and Miculescu in 2008, and then intensively investigated in the last years (the idea is that instead of selfmaps of a metric space X, we consider mappings form the Cartesian product X×...×X to X). Two presented algorithms are counterparts of classical deterministic algorithm and so-called chaos game. The third and fourth one is fitted to special kind of GIFSs - to affine GIFS, which are, in turn, also investigated.     

Surface activity of commercial food grade modified starches

An attempt to quantitative evaluation of the functionality of food grade chemically modified starches in the emulsion systems by estimation of their surface activity as well as the capability of thickening food products was the main purpose of this present work. It was stated that chemically modified starches reveal higher surface activity at air/water and toluene/water interfaces in comparison to the native starch. The increase of the degree of substitution of polar carboxyl groups as well as rather non-polar acetyl ones results in an enhance of surface activity. Starch sodium octenylsuccinate stands out from other investigated starches, in its excellent capability of lowering surface and interfacial tension. Cross-linked starches reveal excellent stabilisation activity at a pH range of 5.5–7.0 but their surface activity is lower than those of other modified starches. Acetylated starch as well as starch sodium octenylsuccinate reveal satisfactory thickening capability up to pH 4.5 and moreover their surface activity (especially of E 1450) allows us to recommend them as functional constituents of food emulsions. Low thickening capability of oxidised starches rather excluded these derivatives from the group of potential functional additives for food emulsions.     

NHC-Rhodium-Catalyzed Synthesis of Novel Silsesquioxanes Containing S-Si and S-Ge Bonds and Their Application in Hydrosilylation Process

The efficient and straightforward NHC-rhodium-catalyzed thiol-silane and thiol-germanane coupling reactions, leading to new classes of functionalized SQ-based materials, are presented for the first time. The proposed strategies use commercially available reagents and show a broad functional groups tolerance, which opens a possibility of effective synthetic procedures of biologically active compounds.     

Bis(μ‐6‐hydroxy­picolinato)‐μ‐oxo‐bis­[di­pyridine­manganese(III)] monohydrate

The title compound, [Mn₂(μ‐O)(C₆H₃NO₃)₂(C₅H₅N)₄]·H₂O, was isolated from the reaction of 2,6‐pyridine­di­carboxylic acid with [Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄] in pyridine. The dimanganese complex has twofold symmetry; the Mn^III atoms are bridged by one oxo and two amidate ligands and show compressed octahedral Jahn–Teller distortion. The molecular packing comprises a three‐dimensional structure constructed by means of extensive intermolecular interactions, including three kinds of hydrogen bonds and π–π interactions.     

Thermoanalytical study of selected transition bivalent metal complexes with 5-carbaldehyde-4-methylimidazole

To compare thermal stability of Co(II), Zn(II), and Cd(II) complexes with 4-CHO-5-MeIm, the two compounds of formula [MnL₂(NO₃)₂] and [NiL₃](NO₃)₂ have been prepared and structurally characterized. Elemental analysis and spectroscopic studies have confirmed a bidentate fashion of coordination of the ligand to Mn(II) and Ni(II) ions. IR and Raman spectra indicate that there are different coordination modes of the NO₃ ^? in compounds: non-coordinated and coordinated. The decomposition process of the studied complexes in nitrogen and argon (Ni(II) complex) atmosphere proceeds in three main stages, except Zn(II) complex, in temperature range 353?C1163?K. The final products of decomposition are CoO, MnO, Cd, ZnN₄, NiN₃. In addition, we have to admit that the different coordination mode of the NO₃ ^? ions in complexes: non-coordinated (in the (1), (4), and (5)) and coordinated (in the (2) and (3)) correlate with its thermal behavior. Thus, temperature ranges of its decompositions are observed: below 533?K and above 533?K, respectively. In Co(II), Mn(II), and Cd(II) complexes the fragments of N-donor atom-containing ligands decompose in the last stages, contrary to Zn(II) and Ni(II) compounds, in which metal ion surrounded by N atoms remains until the end. The course of pyrolysis and molecular structure of the complexes lead to the same conclusion about the strength of metal?Cligand bonds. On the basis of obtained results, it is concluded that the thermal stability of the studied compounds follows the order: (1)?<?(5)?<?(2)?<?(3)?<?(4).     

An unusual nicotinamide derivative, 4-pyridone-3-carboxamide ribonucleoside (4PYR), is a novel endothelial toxin and oncometabolite

Our recent studies identified a novel pathway of nicotinamide metabolism that involves 4-pyridone-3-carboxamide-1-β-D-ribonucleoside (4PYR) and demonstrated its endothelial cytotoxic effect. This study tested the effects of 4PYR and its metabolites in experimental models of breast cancer. Mice were divided into groups: 4T1 (injected with mammary 4T1 cancer cells), 4T1 + 4PYR (4PYR-treated 4T1 mice), and control, maintained for 2 or 21 days. Lung metastasis and endothelial function were analyzed together with blood nucleotides (including 4PYR), plasma amino acids, nicotinamide metabolites, and vascular ectoenzymes of nucleotide catabolism. 4PYR metabolism was also evaluated in cultured 4T1, MDA-MB-231, MCF-7, and T47D cells. An increase in blood 4PYR in 4T1 mice was observed at 2 days. 4PYR and its metabolites were noticed after 21 days in 4T1 only. Higher blood 4PYR was linked with more lung metastases in 4T1 + 4PYR vs. 4T1. Decreased L-arginine, higher asymmetric dimethyl-L-arginine, and higher vascular ecto-adenosine deaminase were observed in 4T1 + 4PYR vs. 4T1 and control. Vascular relaxation caused by flow-dependent endothelial activation in 4PYR-treated mice was significantly lower than in control. The permeability of 4PYR-treated endothelial cells was increased. Decreased nicotinamide but enhanced nicotinamide metabolites were noticed in 4T1 vs. control. Reduced N-methylnicotinamide and a further increase in Met2PY were observed in 4T1 + 4PYR vs. 4T1 and control. In cultured breast cancer cells, estrogen and progesterone receptor antagonists inhibited the production of 4PYR metabolites. 4PYR formation is accelerated in cancer and induces metabolic disturbances that may affect cancer progression and, especially, metastasis, probably through impaired endothelial homeostasis. 4PYR may be considered a new oncometabolite.Subject terms: Mechanisms of disease, Pathogenesis, Breast cancer