Prototypical triplet alkyl phosphonatocarbenes

The current case study focuses on the generation, identification, and characterization of two representative mono- and disubstituted alkyl phosphonatocarbenes by means of matrix isolation techniques in conjunction with density functional theory [B3LYP/6-311++G(d,p)] and coupled cluster [CCSD(T)/cc-pVXZ, X = D, T] computations. The EPR measurements identify both carbenes as triplet ground-state species with D values of 0.660 and 0.623 cm(-1), respectively, exhibiting persistency toward intramolecular reactions (the EPR signal observable in perfluoromethylcyclohexane up to around 70 K for the disubstituted molecule). While the reaction of the carbene center of the conformationally rich tetramethyl bisphosphonatocarbene with the CH bonds of the methyl groups leads to phosphaoxetane at room temperature, its fragmentation via a Wittig-type reaction during high vacuum flash pyrolysis (HVFP) results in dimethyl vinylphosphonate and methyl metaphosphate. The latter has been observed for the first time as an isolated entity.     

Time-resolved and time-integral on-line nuclear orientation measurements of neutron-deficient Hg−Au−Pt−Ir nuclei

The methods of time-resolved and time-integral on-line nuclear orientation have been applied to study short lived nuclei with the NICOLE facility (Nuclear Implantation into Cold On-Line Equipment) at ISOLDE-3 in CERN using beams of^182–186Hg. The half-lives in these decay chains are of the order of seconds and therefore comparable to the spin-lattice relaxation times of the nuclei in iron. As the relaxation rate depends strongly on the g-factor, g-factors of nuclei in the decay chains can be deduced from the observation of the time evolution of γ-ray anisotropy. Using this technique the existence of an isomer in¹⁸⁴Au has been found and the g-factors of¹⁸⁴Au,^184mAu and¹⁸²Au have been determined. Accurate half-lives have been extracted from the data. Time-integral nuclear orientation has been observed for short lived as well as longer lived isotopes of the Hg decay chains. From these measurements, after proper correction for incomplete relaxation, the magnetic moments of^183mPt,¹⁸³Ir and¹⁸²Ir have been derived. The applicability of the time-resolved nuclear orientation technique for nuclei far from stability and its possible limitations is discussed.     

Polymeric hydrogels modified with ornithine and lysine: Sorption and release of metal cations and amino acids

A novel, convenient synthesis, using copper ions, is described for the multigram‐scale preparation of acryloyl and methacryloyl ornithine and lysine without the need to use protecting groups and chromatographic purifications. Three methods of removing the copper ions from the amino acid derivatives were examined. The obtained acryloyl and methacryloyl ornithine and lysine were copolymerized with N‐isopropylacrylamide and N,N′‐methylenebisacrylamide as crosslinking agents, resulting in a series of hydrogels with varying incorporated amino acid content. The relative content of a given amino acid was estimated from the ¹H NMR data and compared with its molar fraction used in the polymerization process. We investigated the influence of the amount of amino acid groups incorporated into the polymer network on the swelling behavior of the gels in the presence of metal ions of different ability to form complexes (Cu²⁺, Co²⁺, and Ca²⁺) with α‐amino acid groups and the sorption of copper ions. Next, the presence of α‐amino acid groups attached to the polymer network was used to bond the compounds which can cocomplex metal ions. Phenylalanine was selected for examination of its cocomplexation of Cu²⁺ with the polymer‐network amino acids and its consecutive release from the gel after appropriate change of pH. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Nicole: New on-line orientation facility at ISOLDE/CERN

This paper presents off-line and on-line orientation results obtained with the new on line nuclear orientation device NICOLE in CERN. Magnetic moments of^187,185Pt ^g and¹⁸⁶Ir ^m , electric quadrupole moment ratios between Pt isotopes with mass number 185, 187 and 189, the spin of the 2 h isomer of¹⁸⁶Ir and a new decay scheme of¹⁸⁴Au involving a metastable state are established. The shape variation versus mass number of the Pt isotopes leads to sign change of the spectroscopic quadrupole moment between A=187 and 185.