Unsymmetrical zinc azaphthalocyanines,peripherally substituted with thiophen-2-yl and 2-functionalized phenoxy groups

Four targeted octasubstituted zinc azaphthalocyanines (ZnAzaPc), substituted with thiophen-2-yl groups and ortho-substituted phenoxy groups, were obtained by cyclotetramerization of 5-aryloxy-6-(thiophen-2-yl)pyrazine-2,3-dicarbonitriles. Thiophen-2-yl substituents are known to extend the macrocyclic conjugation, and thereby cause red-shifted UV–Vis Q-bands. Peripheral phenoxy groups with bulky ortho substituents are expected to suppress aggregation and thereby improve solubility of these compounds. The reagent Zn(quinoline)₂Cl₂ was used for one-step syntheses of these ZnAzaPc. Four tetrasubstituted ZnAzaPc, with phenoxy, (2-isopropyloxy)phenoxy, (2-isopropyl)phenoxy or (2-tert-butyl)phenoxy substituents, were obtained as controls from 5-aryloxypyrazine-2,3-dicarbonitriles. The tetra- and octa-substituted ZnAzaPc, 5 and 6, were obtained in 30–50% yields after purification by chromatography on silica. UV–Vis Q-bands with high molar extinction coefficients (100 000–160 000), were observed at 635 nm for compounds 5, and at 660–665 nm for 6. Grass-green solutions were obtained of compounds 6 in most organic solvents, whereas the less soluble compounds 5 gave blue-green solutions. 2D NMR methods were applied in analyses of DMSO-d₆ solutions of ZnAzaPc 5 and 6. Broad and partly overlapping ¹H NMR signals for some of the compounds indicate some aggregation as well as presence of two or more structural isomers. Molecular ions of ZnAzaPc 5 and 6 were determined by mass spectrometry (MALDI-TOF).     

Ultrafast photodynamics of furan

Ultrafast photodynamics of furan has been studied by time-resolved photoelectron imaging (TRPEI) spectroscopy with an unprecedented time resolution of 22 fs. The simulation of the time-dependent photoelectron kinetic energy distribution (PKED) has been performed with ab initio nonadiabatic dynamics "on the fly" in the frame of time-dependent density functional theory. Based on the agreement between experimental and theoretical time-dependent photoelectron signal intensity as well as on PKED, precise time scales of ultrafast internal conversion from S(2) over S(1) to the ground state S(0) of furan have been revealed for the first time. Upon initial excitation of the S(2) state which has π-π* character, a nonadiabatic transition to the S(1) state occurs within 10 fs. Subsequent dynamics invokes the excitation of the C-O stretching and C-O-C out of plane vibrations which lead to the internal conversion to the ground state after 60 fs. Thus, we demonstrate that the TRPEI combined with high level nonadiabatic dynamics calculations provide fundamental insight into ultrafast photodynamics of chemically and biologically relevant chromophores.     

Ultrafast and high-throughput mass spectrometric assay for therapeutic drug monitoring of antiretroviral drugs in pediatric HIV-1 infection applying dried blood spots

Kaletra® (Abott Laboratories) is a co-formulated medication used in the treatment of HIV-1-infected children, and it contains the two antiretroviral protease inhibitor drugs lopinavir and ritonavir. We validated two new ultrafast and high-throughput mass spectrometric assays to be used for therapeutic drug monitoring of lopinavir and ritonavir concentrations in whole blood and in plasma from HIV-1-infected children. Whole blood was blotted onto dried blood spot (DBS) collecting cards, and plasma was collected simultaneously. DBS collecting cards were extracted by an acetonitrile/water mixture while plasma samples were deproteinized with acetone. Drug concentrations were determined by matrix-assisted laser desorption/ionization-triple quadrupole tandem mass spectrometry (MALDI-QqQ-MS/MS). The application of DBS made it possible to measure lopinavir and ritonavir in whole blood in therapeutically relevant concentrations. The MALDI-QqQ-MS/MS plasma assay was successfully cross-validated with a commonly used high-performance liquid chromatography (HPLC)–ultraviolet (UV) assay for the therapeutic drug monitoring (TDM) of HIV-1-infected patients, and it showed comparable performance characteristics. Observed DBS concentrations showed as well, a good correlation between plasma concentrations obtained by MALDI-QqQ-MS/MS and those obtained by the HPLC-UV assay. Application of DBS for TDM proved to be a good alternative to the normally used plasma screening. Moreover, collection of DBS requires small amounts of whole blood which can be easily performed especially in (very) young children where collection of large whole blood amounts is often not possible. DBS is perfectly suited for TDM of HIV-1-infected children; but nevertheless, DBS can also easily be applied for TDM of patients in areas with limited or no laboratory facilities.     

Assessment of cardiac iron by MRI susceptometry and R2* in patients with thalassemia

A magnetic resonance imaging cardiac magnetic susceptometry (MRI-CS) technique for assessing cardiac tissue iron concentration based on phase mapping was developed. Normal control subjects (n=9) and thalassemia patients (n=13) receiving long-term blood transfusion therapy underwent MRI-CS and MRI measurements of the cardiac relaxation rate R2*. Using MRI-CS, subepicardium and subendocardium iron concentrations were quantified exploiting the hemosiderin/ferritin iron specific magnetic susceptibility. The average of subepicardium and subendocardium iron concentrations and R2* of the septum were found to be strongly correlated (r=0.96, P<.0001), and linear regression analysis yielded CIC (μg Fe/g_{wet tissue})=(6.4±0.4)·R2* _septum (s⁻¹) − (120±40). The results demonstrated that septal R2* indeed measures cardiac iron level.     

Mixed guanidinato/alkylimido/azido tungsten(VI) complexes: synthesis and structural characterization

A series of structurally characterized new examples of pentacoordinated heteroleptic tungsten(VI)-guanidinates complexes are described. Starting out from [WCl(2)(Nt-Bu)(2)py(2)] (1) (py = pyridine) and the guanidinato transfer reagents (TMEDA)Li[(Ni-Pr)(2)CNi-Pr(2)] (2a) (TMEDA = N,N,N',N'-tetramethylethylendiamine) and [Li(NC(NMe(2))(2))](x) (2b), the title compounds [WCl(Nt-Bu)(2)[(Ni-Pr)(2)CNi-Pr(2)]] (3) and [W(Nt-Bu)(2)Cl{NC(NMe(2))(2)]](2) (6) were selectively formed by the elimination of one mole equivalent of lithium chloride. The isopropyl-substituted guanidinato ligand [(Ni-Pr)(2)CNi-Pr(2)} of monomeric 3 is N(1),N(3)-bonded to the tungsten center. The introduction of the sterically less-demanding tetramethyl guanidinato ligand [NC(NMe(2))(2)] expectedly leads to dimeric 6 exhibiting a planar W(2)N(2) ring with the guanidinato group bridging the two tungsten centers via the deprotonated imino N-atom. The remaining chloro ligand of 3 is labile and can be substituted by sterically less-crowded groups such as dimethylamido or azido that yield the presumably monomeric compounds 4 and 5, respectively. A similar treatment of 6 with sodium azide yields the dimeric azido derivative 7. Reacting [WCl(2)(Nt-Bu)(2)py(2)] directly with an excess of sodium azide leads to the dimeric bis-azide species [[W(Nt-Bu)(2)(N(3))(mu(2)-N(3))py](2)]. The new compounds were fully characterized by single-crystal X-ray diffractometry (except 2, 4, and 5), NMR, IR, and mass-spectroscopy as well as elemental analysis. Compound 5, [W(N(3))(Nt-Bu)(2)[(Ni-Pr)(2)CNi-Pr(2)]], can be sublimed at 80 degrees C, 1 Pa.     

Strong Enumeration Reducibilities

We investigate strong versions of enumeration reducibility, the most important one being s-reducibility. We prove that every countable distributive lattice is embeddable into the local structure of the s-degrees. However, is not distributive. We show that on sets s-reducibility coincides with its finite branch version; the same holds of e-reducibility. We prove some density results for . In particular is upwards dense. Among the results about reducibilities that are stronger than s-reducibility, we show that the structure of the bs-degrees is dense. Many of these results on s-reducibility yield interesting corollaries for Q-reducibility as well.     

La suite de Thue–Morse et la catégorie Rec

We define the category $\mathrm{Rec}(\mathbf{K})$ of recurrence matrices over a field K and use it to calculate determinants of Hankel matrices related to the Thue–Morse sequence. To cite this article: R. Bacher, C. R. Acad. Sci. Paris, Ser. I 342 (2006).     

Two- and three-dimensional mapping of the iron distribution in the apoplastic fluid of plant leaf tissue by means of magnetic resonance imaging

A three-dimensional nuclear magnetic resonance imaging (MRI) technique for non-invasive mapping of iron in the apoplastic fluid of plant compartments was developed. The new technique was applied to a leaf of red stem dogwood (Cornus stolonifera). The results are compared with MRI measurements of iron distributions in two dimensions and with total reflection X-ray fluorescence results.