The counter anion effect of (16-ethyl-5,6,7,8-tetrahydro-9H-dibenzo-[b,i][1,4,8,11]tetraazacyclotetradecinato)nickel(II) complexes

The eight nickel(II) complexes with 16-ethyl-5,6,7,8,9,14-hexahydrodibenzo[b, i][1,4,8,11]tetraazacyclotetradecine and a counter anion have been synthesized and their spectroscopic properties were studied. The δ N-H values of NiLCl and NiLBr are observed in a more downfield range than those of NiLPF₆, NiLBF₄ and NiLClO₄ in acetonitrile and nitromethane solutions. The plot of δ N-H against molar conductance is found to be approximately linear. The N-H stretching modes of NiLBF₄, NiLPF₆ and NiLClO₄ shift to lower frequency and those of NiLCl, NiLBr and NiLI shift to higher frequency upon metal-coordination.     

A tris(dialkylamino)sulfonium phenoxide

The title phenoxide has been prepared from phenyl triniethylsilyl ether and tris-(diethylamino) sulfoniuim difluorotrimethylsiliconate. The conductivity measurement and NMR analysis indicate that this phenoxide dissociates into the ions in THF solution.     

Inverted meso-aryl porphyrins with heteroatoms; characterization of thia, selena, and oxa N-confused porphyrins.

Synthesis and characterization of inverted porphyrins containing S, Se, and O are reported. A simple 3 + 1 MacDonald-type condensation using modified tripyrrane containing the N-confused ring and diols afforded various N-confused porphyrins 6a-f in 19-30% yield. The single-crystal X-ray structure of 6b shows a ruffled conformation with tilt angles of 21.11 degrees and 31.23 degrees for the N-confused ring and the adjacent pyrrole ring III, respectively, revealing its severe nonplanarity. Significant changes in C alpha-C beta, C beta-C beta, and C alpha-X bond lengths are observed in 6b relative to free thiophene and pyrrole, suggesting the altered delocalization pathway in the modified N-confused porphyrins. The two molecules in the unit cell show a cyclophane-type noncovalent dimer with a face to face orientation of two N-confused pyrrole rings as a result of the presence of weak N-H...N and C-H...N intermolecular hydrogen bonds involving pyrrole-NH, the N atom of the N-confused ring, and the C atom of the pyrrole ring. A detailed 1H and 13C NMR study by 1D and 2D methods allowed assignments of all the peaks in the free base and protonated forms. NMR studies reveal the presence of three different tautomeric forms in solution for 6c in CDCl3 at low temperature. UV-visible studies reveal absorption band shifts upon heteroatom substitution, and the magnitudes of these shifts are dependent on the nature of the heteroatom. In all cases both monoprotonated and diprotonated species have been identified, and on addition of acid, the first proton goes to the outer N2 atom of the N-confused ring.     

Synthesis of thiazole,oxazole and heterocyclic ring‐substituted 1,2‐dioxanes

The reactions of 4‐bromoacetyl‐3‐methoxy‐3‐methyl‐6,6‐diphenyl‐1,2‐dioxane with thioureas or thioamides gave 3‐methoxy‐3‐methyl‐6,6‐diphenyl‐4‐(4‐thiazolyl)‐1,2‐dioxanes in 63–90% yields. The similar reaction of 4‐bromoacetyl‐3‐methoxy‐3‐methyl‐6,6‐diphenyl‐1,2‐dioxane with acetamide gave 3‐methoxy‐3‐methyl‐4‐(2‐methyl‐4‐oxazolyl)‐6,6‐diphenyl‐1,2‐dioxane in 39% yields. The reactions of 4‐bromoacetyl‐3‐methoxy‐3‐methyl‐6,6‐diphenyl‐1,2‐dioxane with 3‐alkyl‐4‐amino‐5‐mercaptot[1,2,4]triazoles yielded 3‐methoxy‐3‐methyl‐6,6‐diphenyl‐4‐[3‐(5‐alkyl[1,2,4]triazolo[3,4‐b]‐2,3‐dihydro‐6H‐[1,3,4]thiadiazinyl)]‐1,2‐dioxanes in moderate yields (43–46%).     

Efficient Synthesis of β‐Primeverosides as Aroma Precursors by Transglycosylation of β‐Diglycosidase from Penicillium multicolor

The enzyme activity transferring a β‐primeverosyl unit was found from culture filtrates of Penicillium multicolor IAM7153 and was useful for synthesizing a series of β‐primeverosides via a β‐primeverosyl transfer reaction in an aqueous‐organic biphasic system. With the acceptors benzyl alcohol, 2‐phenylethanol, and (Z)‐3‐hexenol, the enzyme induced the transfer products benzyl, 2‐phenylethyl, and (Z)‐3‐hexyl β‐primeverosides in high yields of 51% to 70% based on the donor added. When geraniol and eugenol were used as acceptors, the corresponding geranyl and eugenyl β‐primeverosides were obtained in lower yields of 8% to 12%. The enzyme was an excellent tool for producing naturally occurring β‐primeverosides on a mmol scale.     

A comparative study using liquid scintillation counting and X-ray spectrometry to determine 55Fe in radioactive wastes

The radionuclide ⁵⁵Fe was determined in samples of radioactive wastes from the water cleanup system of the IEA-R1 nuclear research reactor. In order to validate the results, the ⁵⁵Fe activity concentration was measured in eight waste samples and in six simulated samples containing the most important interfering radionuclides. A simple method was employed to separate and purify ⁵⁵Fe from other radionuclides present in these samples, combining co-precipitation with ammonium hydroxide and purification with anionic ion-exchange resin, which enables ⁵⁵Fe to be quantified either by liquid scintillation counting (LSC) or by X-ray spectrometry using a low-energy germanium spectrometer (LEGe). Both measurement methods were used so that the separation and purification process could be confirmed by comparison of spectra with and without the utilization of anionic ion-exchange resin. Activity and interferences were compared in the results obtained from LSC and LEGe measurement methods.