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At least 451 records · Page 25Linked to original sources
PubMed2006

Phosphorus-nitrogen compounds: synthesis and spectral investigations on new spiro-cyclic phosphazene derivatives.

The condensation reaction of {N-[(2-hydroxyphenylmethyl)amino]-4,6-dimethylpyridine} (2), which is a reduction product of 1, with trimer N(3)P(3)Cl(6) affords partially a substituted spiro-cyclic phosphazene derivative (3). The fully substituted phosphazenes (4 and 5) have also been obtained from the reactions of 3 with the excess of pyrrolidine and morpholine. The characterizations and spectral investigations of these compounds have been made by elemental analyses, FTIR, 1H-, 13C-, 31P NMR, correlation spectroscopy (COSY), heteronuclear chemical shift correlation (HETCOR), heteronuclear multiple-bond correlation (HMBC) and mass spectroscopy (MS). The salient features of spectral data of these compounds have been discussed.

Carbon Isotopes↗
PubMed2006

The determination of phosphorus containing compounds in dental casting investment products by 31P solid-state MAS-NMR spectroscopy.

OBJECTIVES: To use (31)P solid-state MAS-NMR to determine the phosphorus compounds that occur in dental casting investment material: (a) as-received, (b) after setting and (c) after burn-out and discover whether such compounds are the same in each material across a product range. METHODS: [(1)H] High powered decoupling (HPDC) and [(1)H] cross-polarization (CP) (31)P solid-state MAS-NMR spectroscopy at a resonance frequency of 121.4 MHz were used. Six commercial products were examined. Manufacturer's instructions were followed and a special liquid was used without dilution. RESULTS: All products contain ammonium dihydrogen phosphate as the acid phosphate required for the setting reaction. All set by the formation of struvite and significant amounts of amorphous magnesium orthophosphate. In three products, lesser amounts of newberyite were present and in another the equivalent amorphous compound was formed. When burnt-out, magnesium metaphosphate or pyrophosphate was the dominant matrix compound. A higher burn-out temperature favoured pyrophosphate formation. Farringtonite was present to a lesser extent with the metaphosphate. SIGNIFICANCE: Compounds that were not detected in earlier X-ray powder diffraction spectroscopy studies were detected by NMR, notably amorphous and glassy compounds (magnesium orthophosphate in set investment and magnesium metaphosphate in burnt-out material). The variation between products was significant and far greater than expected from the published scientific literature. Since the formation of compounds is affected by technical procedure and ambient conditions, these findings could offer some insight into the cause of the unpredictability of expansion measurements between laboratories. Further research is being undertaken.

Dental Casting Investment↗
PubMed1987

Iron oxidation in Mops buffer. Effect of phosphorus containing compounds.

Fe2+ autoxidation in Mops buffer both in absence and presence of substoichiometric concentrations of EDTA, H2O2 and of Fe3+ is greatly affected by phosphorus containing compounds. They increase the lag phase, characteristic of Fe2+ oxidation in this buffer, and decrease the rate of the reaction. This effect is due to the phosphates of the molecule. The ability of the different compounds tested to affect Fe2+ oxidation, however, appears to be influenced also by the rest of the molecule. The concentration of the different phosphorus containing compounds that inhibits 50% of Fe2+ oxidation is rather different. The effect exerted appears to be the result of an equilibrium between an inhibitory effect on the pathway of Fe2+ oxidation that occurs in Mops buffer and the onset of a different oxidation pathway of Fe2+ similar to that occurring in Na phosphate buffer. A hypothesis is proposed that the phosphorus containing compounds inhibit Fe2+ oxidation by binding Fe3+ and decreasing its ability to accelerate Fe2+ autoxidation. It is suggested that the presence in vitro and in vivo of phosphorus containing compounds may modify Fe2+ autoxidation and thus the production of oxygen active species.

Adenosine Triphosphate↗
PubMed1990

Changes in some nutrients of fenugreek (Trigonella Foenum graecum L.) seeds during water boiling.

Fenugreek seeds were boiled in water for various lengths of time (5, 10 and 15 min). Changes in weight, volume, moisture content, total sugars, nitrogen compounds, minerals, phosphorus compounds, phytic acid, amino acids and the in vitro digestibility of the seeds as well as the total solids of the boiling water were determined. Data indicated that there was an increase in both weight and volume as well as the in vitro digestibility of fenugreek seeds especially after the first 5 minutes of boiling. On the other hand, a decrease in the content of total sugars, protein compounds, calcium, magnesium, phytic acid, phosphorus and amino acids was observed. The reduction was accompanied by a gradual increase in the total solids of boiling water.

Amino Acids↗
PubMed2005

Titania-coated monolithic silica as separation medium for high performance liquid chromatography of phosphorus-containing compounds.

A method of preparing titania-coated monolithic silica stationary phase has been developed to achieve liquid chromatographic separation of phosphorus-containing compounds, which have recently been attracting increasing attention in biochemical research. The titania-coated silica columns exhibited efficient separation with low pressure drop, which is a typical feature of monolithic structures, and also possessed phospho-selectivity, which is a unique property of the titania surface. The material characteristics of titania-coated monolithic silica were examined, and then resin-clad columns were applied to the HPLC analysis of phosphorylated compounds. Highly efficient separation of phosphorylated substances indicated that the novel titania-coated monolithic silica column will find applications as a useful tool in the field of biochemistry, especially in post-genomic analyses.

Journal Article↗