Multifrequency Nuclear Magnetic Resonance as an Efficient Tool To Investigate Heterospin Complexes in Solutions.

We report a multifrequency nuclear magnetic resonance (NMR) study of heterospin complexes [Eu(SQ)L], where SQ is 3,6-di(-butyl)-1,2-semiquinone, L is tetrahydrofuran (THF), pyridine (Py), or 2,2'-dipyridyl (Dipy), and is the number of diamagnetic ligands. Multifrequency NMR experiments allowed us to determine the effective paramagnetic shifts of the ligands (L = THF or Py) and the chemical equilibrium constant for [Eu(SQ)(THF)]. In addition, we have found a strong magnetic field effect on the NMR line broadening, giving rise to very broad NMR lines at high magnetic fields.

Photochemistry of tris(2,3,5,6-tetrathiaaryl)methyl radicals in various solutions.

During the last decades, persistent tris(2,3,5,6-tetrathiaaryl)methyl radicals (TAMs) have attracted much attention due to their applications in oximetry, EPR tomography, and as spin labels in pulsed dipolar EPR spectroscopy. Recently, researchers proposed to use TAM radicals as spin labels and/or a partner for photoinduced spin labels. Thus, the questions of their photochemical stability and mechanism of degradation under UV irradiation have become relevant and important.

Trityl-based alkoxyamines as NMP controllers and spin-labels.

Recently, new applications of trityl-nitroxide biradicals were proposed. In the present study, attachment of a trityl radical to alkoxyamines was performed for the first time. The rate constants of C-ON bond homolysis in these alkoxyamines were measured and found to be equal to those for alkoxyamines without trityl.

Octahedral molybdenum cluster complexes with aromatic sulfonate ligands.

This article describes the synthesis, structures and systematic study of the spectroscopic and redox properties of a series of octahedral molybdenum metal cluster complexes with aromatic sulfonate ligands (BuN)[{MoX}(OTs)] and (BuN)[{MoX}(PhSO)] (where X is Cl, Br or I; OTs is p-toluenesulfonate and PhSO is benzenesulfonate). All the complexes demonstrated photoluminescence in the red region and an ability to generate singlet oxygen. Notably, the highest quantum yields (>0.

pH-sensitive C-ON bond homolysis of alkoxyamines of imidazoline series: a theoretical study.

The pH-dependent kinetics of C-ON bond homolysis reactions of the four alkoxyamines (viz., the derivatives of 2-(4-(dimethylamino)-2-ethyl-5,5-dimethyl-2-(pyridin-4-yl)-2,5-dihydro-1H-imidazol-1-oxyl and 2-(2-carboxyethyl)-5,5-diethyl-2,4-dimethyl-2,5-dihydro-1H-imidazol-1-oxyl) in water solution have been scrutinized using DFT calculations (M06-2X/6-311++G(2df,p) level of theory with the PCM model). On the basis of computations, the experimental results obtained before (J.

pH-sensitive C-ON bond homolysis of alkoxyamines of imidazoline series with multiple ionizable groups as an approach for control of nitroxide mediated polymerization.

Recently, a new concept of pH-switchable agents for reversible addition-fragmentation chain transfer (RAFT) polymerization has been introduced by Benaglia et al. (J. Am.