Gyromagnetic ratio of the 159 keV 3/2+ state of117Sn

TheF-spin formalism is employed to extract scalar boson effective charges from theB(E2, 2 ₁ ⁺ →0_g) systematics in rare-earth nuclei.     

Molybdenum chalcogenobenzimidato complexes: radical synthesis and nitrile extrusion via beta-EPh (E = S, Se, and Te) elimination

Molybdenum chalcogenobenzimidates of formula (Ph[PhE]C=N)Mo(N[t-Bu]Ar)(3) (Ar = 3,5-C(6)H(3)Me(2)) have been obtained by treatment of Mo(N[t-Bu]Ar)(3) sequentially with benzonitrile and 0.5 equiv of PhEEPh (E = S, Se, and Te). Molecular structure determinations have been carried out for the S and Se variants. The Te variant extrudes PhCN forming structurally characterized (PhTe)Mo(N[t-Bu]Ar)(3) with facility assessed via stopped-flow kinetic measurements, while the Se and S analogues exhibit increasing stability. Quantum chemical calculations and solution calorimetry have been employed as an aid to interpretation of the PhCN extrusion reaction.     

Thermochemistry of molybdenum tricarbonyl complexes of arenes and cyclic polyolefins

The heats of reaction of arene, cycloheptatriene, and cyclooctatetraene complexes of molybdenum tricarbonyl with pyridine yielding (py)₃Mo(CO)₃ have been measured by solution calorimetry. Reaction of toluene molybdenum tricarbonyl with cyclopentadiene yielding HMo(CO)₃C₅H₅ and with tetrahydrofuran yielding (THF)₃Mo(CO)₃ have also been studied thermochemically. These measurements yield accurate values for the enthalpy of arene exchange in methylene chloride solution for a number of organomolybdenum complexes. The order of stability: benzene < toluene < cyclooctatetraene < mesitylene < hexamethylbenzene < cycloheptatriene < (tris)-tetrahydrofuran < η⁵-cyclopentadienylhydrido < (tris)-pyridine spans a range of 31 kcal/mol.The enthalpy of isomerization of cycloheptatriene to toluene is reduced by 7.1 ± 1.2 kcal/mol upon coordination to molybdenum tricarbonyl, indicative of a loss of “resonance” energy for the complexed arene. The MoH bond strength in HMo(CO)₃C₅H₅ is estimated as 66 ± 8 kcal/mol. The importance of entropic factors in arene exchange is discussed.     

Sublevel decay kinetics of the triplet state of bacteriochlorophyll a and b in methyltetrahydrofuran at 1.2 K

The decay rates of the triplet sublevels of monomeric BChl a and b have been reexamined with pulsed microwave excitation. Our values of k_x and k_y are significantly higher than published values. The new results are discussed in relation to the exciton model of the special pair making up the primary electron donor in photosynthetic purple bacteria.     

The nuts and bolts of distance determination and zero- and double-quantum coherence in photoinduced radical pairs

We describe in some detail the new method of distance determination for a photoinduced radical pair. Emphasis is on giving the nuts and bolts of the calculations that result in analytical expressions for in- and out-of-phase electron spin echo (ESE) envelope modulations, pulse flip-angle dependencies, zero- and double-quantum coherences, and the distance between the two radicals. The theoretical results are illustrated by a set of recent experiments on photosynthetic reaction centers.     

Gyromagnetic ratios of collective states of166Er

The static hyperfine field ofB _hf ^4.2k (ErHo) = 739(18)T of a ferromagnetic holmium single crystal polarized in an external magnetic field of ± 0.48T at ～4.2K was used for integral perturbed γ-γ angular correlation (IPAQ measurements of the g-factors of collective states of¹⁶⁶Er. The 1,200y ^166m Ho activity was used which populates the ground state band and the γ vibrational band up to high spins. The results: $$\begin{gathered} g(4_g^ + ) = + 0.315(16) \hfill \\ g(6_g^ + ) = + 0.258(11) \hfill \\ g(8_g^ + ) = + 0.262(47)and \hfill \\ g(6_\gamma ^ + ) = + 0.254(32) \hfill \\ \end{gathered}$$ exhibit a significant reduction of the g-factors with increasing rotational angular momentum. The followingE2/M1 mixing ratios of interband transitions were derived from the angular correlation coefficients: $$\begin{gathered} 5_\gamma ^ + \Rightarrow 4_g^ + :\delta (810keV) = - (36_{ - 7}^{ + 11} ) \hfill \\ 7_\gamma ^ + \Rightarrow 6_g^ + :\delta (831keV) = - (18_{ - 2}^{ + 3} )and \hfill \\ 7_\gamma ^ + \Rightarrow 8_g^ + :\delta (465keV) = - (63_{ - 12}^{ + 19} ). \hfill \\ \end{gathered}$$ The results are discussed and compared with theoretical predictions.     

Photocaged pendent thiol polymer brush surfaces for postpolymerization modifications via thiol‐click chemistry

In this work, a postpolymerization surface modification approach is reported that provides pendent thiol functionality along the polymer brush backbone using the photolabile protection chemistry of both o‐nitrobenzyl and p‐methoxyphenacyl thioethers. Poly(2‐hydroxyethyl methacrylate) (pHEMA) brushes were synthesized via surface‐initiated atom transfer radical polymerization, after which the pHEMA hydroxyl groups were esterified with 3‐(2‐nitrobenzylthio)propanoic acid or 3‐(2‐(4‐methoxyphenyl)‐2‐oxoethylthio)propanoic acid to provide the photolabile protected pendent thiols. Addressing the protecting groups with light not only affords spatial control of reactive thiol functionality but enables a plethora of thiol‐mediated transformations with isocyanates and maleimides providing a modular route to create functional polymer surfaces. This concept was extended to block copolymer brush architectures enabling the modification of the chemical functionality of both the inner and outer blocks of the block copolymer surface. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Use of capillary electrophoresis with laser-induced fluorescence detection to screen and liquid chromatography–tandem mass spectrometry to confirm sulfonamide residues: Validation according to European Union 2002/657/EC

A multiresidue method is described for determining six sulfonamides (SAs) (sulfadiazine, sulfathiazole, sulfamethazine, sulfamethoxazole, sulfaquinoxaline and sulfadimethoxine) in liver by a capillary electrophoresis screening method and a liquid chromatography coupled to tandem mass spectrometry confirmatory assay. Samples were prepared by homogenizing the tissue, with sodium hydroxide and acetonitrile. After evaporation, extracts were injected in the capillary electrophoresis system or mass spectrometry system for confirmatory analysis. The detection of analytes was achieved by laser-induced fluorescence in capillary electrophoresis. Procedures were validated according to the European Union regulation 2002/657/EC determining specificity, selectivity and detection capability for screening method and decision limit, detection capability, specificity, selectivity, trueness and precision for confirmation method. The results of validation process demonstrate that the method is suitable for application in Brazilian statutory veterinary drug residue surveillance programs. Capillary electrophoresis was proved to be a fast, robust method with low time and reagents consumption.