Differences in actinide metal-ligand orbital interactions: comparison of U(IV) and Pu(IV) β-ketoiminate N,O donor complexes

Syntheses and characterization of UCl(2)((Ar)acnac)(2), UI(2)((Ar)acnac)(2), and PuI(2)((Ar)acnac)(2) are reported ((Ar)acnac denotes a bis-phenyl β-ketoiminate ligand where Ar = 3,5-(t)Bu(2)C(6)H(3)). Structural analyses and computations show significant metal-ligand orbital interaction differences in U(IV) vs. Pu(IV) bonding.     

Studies on photoinduced effects in pulse-electrodeposited Ag/Hg-1212/CdSe hetero-nanostructures

Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined. The increase in carrier concentration across the junction due to photo-irradiation has been observed.     

Effect of laser irradiation of C-V characteristics of electrodeposited Ag/Tl-2223/CdSe hetero-nanostructures

One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation, metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction built-in-potential (V _D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied.     

Halodiazophosphonates, a new class of diazo compounds for the diastereoselective intermolecular Rh(II) catalyzed cyclopropanation

(Halodiazomethyl)phosphonates 2A-C have been generated by a one-pot procedure via a clean, efficient, and rapid deprotonation/electrophilic halogenation sequence from diethyl diazomethylphosphonate 1 (EDP). Subsequent intermolecular Rh(II)-catalyzed cyclopropanation afforded the corresponding halocyclopropylphosphonates 3-10 in moderate to high yields and high diastereomeric ratios. Catalyst loadings down to 0.1 mol % as well as clean and selective product formation were achieved.     

Bonding Trends Traversing the Tetravalent Actinide Series: Synthesis, Structural, and Computational Analysis of An(IV)((Ar)acnac)(4) Complexes (An = Th, U, Np, Pu; (Ar)acnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-(t)Bu(2)C(6)H(3))

A series of tetravalent An(IV) complexes with a bis-phenyl β-ketoiminate N,O donor ligand has been synthesized with the aim of identifying bonding trends and changes across the actinide series. The neutral molecules are homoleptic with the formula An((Ar)acnac)(4) (An = Th (1), U (2), Np (3), Pu (4); (Ar)acnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-(t)Bu(2)C(6)H(3)) and were synthesized through salt metathesis reactions with actinide chloride precursors. NMR and electronic absorption spectroscopy confirm the purity of all four new compounds and demonstrate stability in both solution and the solid state. The Th, U, and Pu complexes were structurally elucidated by single-crystal X-ray diffraction and shown to be isostructural in space group C2/c. Analysis of the bond lengths reveals shortening of the An-O and An-N distances arising from the actinide contraction upon moving from 1 to 2. The shortening is more pronounced upon moving from 2 to 4, and the steric constraints of the tetrakis complexes appear to prevent the enhanced U-O versus Pu-O orbital interactions previously observed in the comparison of UI(2)((Ar)acnac)(2) and PuI(2)((Ar)acnac)(2) bis-complexes. Computational analysis of models for 1, 2, and 4 (1a, 2a, and 4a, respectively) concludes that both the An-O and the An-N bonds are predominantly ionic for all three molecules, with the An-O bonds being slightly more covalent. Molecular orbital energy level diagrams indicate the largest 5f-ligand orbital mixing for 4a (Pu), but spatial overlap considerations do not lead to the conclusion that this implies significantly greater covalency in the Pu-ligand bonding. QTAIM bond critical point data suggest that both U-O/U-N and Pu-O/Pu-N are marginally more covalent than the Th analogues.     

Quantitative analysis of D-24851, a novel anticancer agent, in human plasma and urine by liquid chromatography coupled with tandem mass spectrometry

The development of a liquid chromatography/tandem mass spectrometric assay for the quantitative analysis of the novel tubulin inhibitor D-24851 in human plasma and urine is described. D-24851 and the deuterated internal standard were extracted from 250 microL of plasma or urine using hexane/ether (1:1, v/v). Subsequently, 10-microL aliquots of reconstituted extracts were injected onto an Inertsil ODS analytical column (50 x 2.0 mm i.d., 5 microm particle size). An eluent consisting of methanol/5 mM ammonium acetate, 0.004% formic acid in water (80:20, v/v) was pumped at a flow rate of 0.2 mL/min. An API 365 triple quadrupole mass spectrometer was used in the multiple reaction monitoring mode for sensitive detection. For human plasma a dynamic range of 1-1000 ng/mL was validated, and for human urine a range of 0.25-50 ng/mL. Validation was performed according to the most recent FDA guidelines and all results were within requirements. The assay has been successfully applied to support a phase I clinical trial with orally administered D-24851.     

Uranium(IV) Sulfates: Investigating Structural Periodicity in the Tetravalent Actinides

Chemical trends within the periodic table are frequently used as guides for predicting reactivity, structure, and electronic properties of the elements. While these trends have been rigorously investigated for the transition metals, the understanding of trends within the actinide series is elementary in comparison. Herein, we report the synthesis and characterization of five new U(IV) sulfate compounds and discuss their relationship to previously reported An(IV) sulfate species, an analysis that allows for the elucidation of solid state trends across the actinides. One such trend suggests the increase in Lewis acidity that occurs when traversing the actinides from thorium to plutonium promotes bidentate binding of the sulfate ligand as long as complexation can outcompete the resulting increase in steric pressure. This hypothesis correlates well with the experimental results previously reported for the solution phase speciation in An(IV) sulfate systems.     

Reactivity of UH3 with mild oxidants

Addition of 2 equiv of I2 to a stirring suspension of UH3 in Et2O results in vigorous gas evolution and the formation of UI4(OEt2)2 (1), which can be isolated in good yields as an air- and moisture-sensitive brick-red powder. Addition of 3 equiv of AgBr to UH3 in DME produces UBr3(DME)2 (2), while addition of 4 equiv of AgX to UH3 in DME-CH2Cl2 provides UX4(DME)2 (X = Br, 3; Cl, 4). Similarly, the reaction of 4 equiv of AgOTf with UH3 in neat DME generates U(OTf)4(DME)2 (5). Each of these reactions proceeds with the evolution of hydrogen. Complex can also be generated by reaction of 4 equiv of Me3SiI with UCl4 in Et2O. All complexes were fully characterized, including analysis by X-ray crystallography.     

Borane-mediated silylation of a metal-oxo ligand

The addition of 1 equiv of HSiPh(3) to UO(2)((Ar)acnac)(2) ((Ar)acnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-(t)Bu(2)C(6)H(3)), in the presence of 1 equiv of B(C(6)F(5))(3), results in the formation of U(OSiPh(3))(OB{C(6)F(5)}(3))((Ar)acnac)(2) (1), via silylation of an oxo ligand and reduction of the uranium center. The addition of 1 equiv of Cp(2)Co to 1 results in a reduction to uranium(IV) and the formation of [Cp(2)Co][U(OSiPh(3))(OB{C(6)F(5)}(3))((Ar)acnac)(2)] (2) in 78% yield. Complexes 1 and 2 have been characterized by X-ray crystallography, while the solution-phase redox properties of 1 have been measured with cyclic voltammetry.     

玫瑰红与介孔二氧化硅生物光敏复合体的激发态性质

以光动力治疗药物玫瑰红( Rose Bengal,RB)与孔径为2.7nm的介孔二氧化硅MCM-41为主体材料进行结构组装,制备了具有生物光敏功能的介孔复合载体.对介孔复合载体的性质进行了表征,通过紫外吸收和荧光光谱对玫瑰红RB在介孔孔道内的光学性质进行了分析.由于介孔道表面与RB的相互作用,不同结构和性质的内孔道中的...