Amorphous Calcium Phosphates: Solvent-Controlled Growth and Stabilization through the Epoxide Route

Calcium phosphates stand among the most promising nanobiomaterials in key biomedical applications, such as bone repairment, signalling or drug/gene delivery. Their intrinsic properties as crystalline structure, composition, particle shape and size define their successful use. Among these compounds, metastable amorphous calcium phosphate (ACP) is currently gaining particular attention due to its inherently high reactivity in solution, which is crucial in bone development mechanisms. However, the preparation of this highly desired (bio)material with control over its shape, size and phase purity remains as a synthetic challenge. In this work, the epoxide route was adapted for the synthesis of pure and stable ACP colloids. By using biocompatible solvents, such as ethylene glycol and/or glycerine, it was possible to avoid the natural tendency of ACP to maturate into more stable and crystalline apatites. Moreover, this procedure offers size control, ranging from small nanoparticles (60 nm) to micrometric spheroids (>500 nm). The eventual fractalization of the internal mesostructured can be tuned, by simply adjusting the composition of the ethylene glycol:glycerine solvent mixture. These findings introduce the use of green solvents as a new tool to control crystallinity and/or particle size in the synthesis of nanomaterials, avoiding the use of capping agents and preserving the natural chemical reactivity of the pristine surface.     

Vitamin B12 Phosphate Conjugation and Its Effect on Binding to the Human B12‐Binding Proteins Intrinsic Factor and Haptocorrin

The binding of vitamin B₁₂ derivatives to human B₁₂ transporter proteins is strongly influenced by the type and site of modification of the cobalamin original structure. We have prepared the first cobalamin derivative modified at the phosphate moiety. The reaction conditions were fully optimized and its limitations examined. The resulting derivatives, particularly those bearing terminal alkyne and azide groups, were isolated and used in copper‐catalyzed alkyne–azide cycloaddition reactions (CuAAC). Their sensitivity towards light revealed their potential as photocleavable molecules. The binding abilities of selected derivatives were examined and compared with cyanocobalamin. The interaction of the alkylated derivatives with haptocorrin was less affected than the interaction with intrinsic factor. Furthermore, the configuration of the phosphate moiety was irrelevant to the binding process.     

Temperature Dependence of the Surface Tension of Alkali Metals: A Unified Correlation

Abstract

In this work, new definitions of the normalized temperature and surface tension are proposed which result in a single plot for the surface tension of molten alkali metals. The functional dependence of the reduced surface tension on the reduced temperature can be adequately described by a straight line; the intercept and slope have been obtained using the linear regression approach. The method proposed herein predicts the values of surface tension at various temperatures with an average error of about 5%.     

Flame‐retardant and mechanical properties of phenolic foams toughened with polyethylene glycol phosphates

Three kinds of polyethylene glycol phosphates (PEGPs) toughening agents were synthesized by esterification of phosphorus pentoxide (P₂O₅) with polyethylene glycol and characterized by Fourier transform infrared spectra and ³¹P nuclear magnetic resonance. A series of lightweight phenolic foams toughened with different loadings of PEGPs were prepared. Optical microscopy results show that the addition of PEGPs with small molecular weight PEG improves the structural homogeneity of phenolic foams obviously. The flame retardancy of toughened phenolic foams was evaluated by using UL 94, limiting oxygen index, and cone calorimeter. The results indicate that the incorporation of PEGPs not only increases the toughness of phenolic foams but also improves their flame retardancy. Moreover, the thermal stability of PEGPs and the toughened foams was investigated by thermogravimetric analysis. Copyright © 2013 John Wiley & Sons, Ltd.     

Calixarenes as Polyhapto-aromatic Ligands: Alkali Metal Ions and Sulfonated Calixarenes

Crystal structure determinations for the hexarubidium and octacesium derivatives of calix[6]arene hexasulfonic acid, as well as of a new solvate of the pentasodium derivative of calix[4]arene tetrasulfonic acid, and comparison with structural data from the literature for alkali metal complexes of sulfonated calixarenes, have provided further evidence for the importance of interactions with aromatic ~ -electrons for the heavier alkali metal cations. There is evidence as well that this interaction can be enhanced by extended ionization of the sulfonated calixarene.     

Synthesis,Characterization and Properties of a Novel Environmentally Friendly Mono Azo Disperse Dye and Its Application on Polyethylene Terephthalate (PET)

The aim of this research is to achieve the synthesis of a novel mono azo disperse dye containing both a β‐naphthyl acetate group and carboxylic acid ester group and application on PET fabric. In this study the dyeing properties have also been investigated. The synthesized dye was characterized using UV‐Vis, FTIR, ¹H NMR and ¹³C NMR spectroscopic techniques. To investigate alkali‐clearability, both alkali‐hydrolysis behavior and the effect of its fastness properties with regard to PET fabric were examined. This dye showed a reasonable level of hydrolysis under relatively mild alkaline conditions. The application of the dye to PET fabric showed good leveling and building up properties. Estimating fastness properties of the dyed fabric showed excellent wash, rubbing fastness, good light and sublimation fastness. The results furthermore displayed that the synthesized dye offers the option of alkali‐clearing process over that of a conventional reduction‐clearing process. Therefore, the value of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD) and water pollution as well as the expenditure of production were decreased.     

Gas chromatographic retention of alkyl phosphates on ionic liquid stationary phases

Retention behaviors of alkyl phosophates were studied on a series of ionic liquid gas chromatography columns. The selectivity of the IL columns for alkyl phosphates were compared with a 5% phenyl column as a route to evaluating the potential use of IL columns in the analysis of alkyl phosphates in petroleum samples in both one- and multi-dimensional GC. Most interestingly, we demonstrate for the first time the dependence of elution order on separation temperature for members of a homologous series of compounds. At low temperatures it was found that trihexyl phosphate eluted before trioctyl phosphate, while at higher temperatures this pattern was reversed.     

Divergent Synthesis of All Possible Optically Active Regioisomers of Myo‐Inositol Mono‐ and Bisphosphates

All possible optically active regioisomers of myo‐inositol mono‐ and bisphosphates were synthesized using inositol derivatives suitably protected with various protecting groups (IR_ns) as key intermediates. A series of procedures including Novozym 435 catalyzed enzymatic resolution of (3aR,4S,7S,7aR)‐rel‐3a,4,7,7a‐tetrahydro‐2,2‐dimethyl‐1,3‐benzodioxole‐4,7‐diol diacetate, several protection and deprotection reactions, and acyl migration afforded two enantiomeric pairs of IR₅ and six enantiomeric pairs of IR₄. Phosphorylation of these key intermediates by the phosphitylation and oxidation procedure gave the target products after removal of the protecting groups.      

Asymmetric Michael addition of 2-alkoxyphenyl α-substituted nitroacetates to non-prochiral α,β-unsaturated carbonyl compounds catalyzed by podand-type alkali metal 2′-substituted 1,1′-binaphthalen-2-oxides

The asymmetric Michael addition of 2-alkoxyphenyl α-substituted nitroacetates to non-prochiral α,β-unsaturated carbonyl compounds catalyzed by 10 mol % of sodium 2′-[2-(2-methoxyethoxy)ethoxy]-1,1′-binaphthalen-2-oxide gave the desired adducts in high yields with up to 95% ee.