N-Heterocyclic Carbene to Actinide d-Based π-bonding Correlates with Observed Metal-Carbene Bond Length Shortening Versus Lanthanide Congeners.

Comparison of bonding and electronic structural features between trivalent lanthanide (Ln) and actinide (An) complexes across homologous series' of molecules can provide insights into subtle and overt periodic trends. Of keen interest and debate is the extent to which the valence f- and d-orbitals of trivalent Ln/An ions engage in covalent interactions with different ligand donor functionalities and, crucially, how bonding differences change as both the Ln and An series are traversed. Synthesis and characterization (SC-XRD, NMR, UV-vis-NIR, and computational modeling) of the homologous lanthanide and actinide N-heterocyclic carbene (NHC) complexes [M(CMe)(X)(I)] {X = I, M = La, Ce, Pr, Nd, U, Np, Pu; X = Cl, M = Nd; X = I/Cl, M = Nd, Am; and I = [C(NMeCMe)]} reveals consistently shorter An-C vs Ln-C distances that do not substantially converge upon reaching Am/Nd comparison.

Oxidative Dissolution of Lanthanide Metals Ce and Ho in Molten GaCl.

Gallium trichloride (GaCl) was used as a solvent for the oxidative dissolution of the lanthanide (Ln) metals cerium (Ce) and holmium (Ho). Reactions were performed at temperatures above 100 °C in sealed vessels to maintain the liquid phase for GaCl during the oxidizing reactions. The best results were obtained from reactions using 8 equiv of GaCl to metal where the inorganic complexes [Ga][Ln(GaCl)] [Ln = Ce (), Ho ()] could be isolated.

Isostructural σ-hydrocarbyl phospholide complexes of uranium, neptunium, and plutonium.

σ-Hydrocarbyl complexes of the form [M(η-PCMe)(μ-η:η-CHPh)K(η-arene)] (M = La, Ce, Pr, U, Np, Pu; arene = benzene or toluene) were synthesised in one-pot reactions from [MI(THF)], or [U(BH)(toluene)] (M = U). All complexes were examined by multinuclear (H, C{H}, P{H}) NMR and UV-vis-NIR spectroscopy, as well as single-crystal X-ray diffraction from which molecular metal-phosphorus bonds for Np and Pu, and a σ-hydrocarbyl metal-carbon bond for Pu, have been structurally authenticated.

T1 relaxation time of ISMRM/NIST T1 phantom spheres at 7 T.

T1 relaxation times of the 14 T1 phantom spheres that make up the standard International Society for Magnetic Resonance in Medicine (ISMRM)/National Institute of Standards and Technology (NIST) system phantom are reported at 7 T. T1 values of six of the 14 T1 spheres at 7 T (with T1 > 270 ms) have been reported previously, but, to the best of our knowledge, not all of the T1s of the 14 T1 spheres at 7 T have been reported before. Given the increasing number of 7-T MRI systems in clinical settings and the increasing need for T1 phantoms that cover a wide range of T1 relaxation times to evaluate rapid T1 mapping techniques at 7 T, it is of high interest to obtain accurate T1 values for all the ISMRM/NIST T1 spheres at 7 T.

Homoleptic Uranium-Bis(acyl)phosphide Complexes.

The first uranium bis(acyl)phosphide (BAP) complexes were synthesized from the reaction between sodium bis(mesitoyl)phosphide () or sodium bis(2,4,6-triisopropylbenzoyl)phosphide () and UI(1,4-dioxane). Thermally stable, homoleptic BAP complexes were characterized by single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy, when appropriate, for the elucidation of the electronic structure and bonding of these complexes. EPR spectroscopy revealed that the BAP ligands on the uranium center retain a significant amount of electron density.

Synthesis, solid-state, solution, and theoretical characterization of an "in-cage" scandium-NOTA complex.

Developing chelators that strongly and selectively bind rare-earth elements (Sc, Y, La, and lanthanides) represents a longstanding fundamental challenge in inorganic chemistry. Solving these challenges is becoming more important because of increasing use of rare-earth elements in numerous technologies, ranging from paramagnets to luminescent materials. Within this context, we interrogated the complexation chemistry of the scandium(III) (Sc) trication with the hexadentate 1,4,7-triazacyclononane-1,4,7-triacetic acid (HNOTA) chelator.

[AnI(THF)] (An = Np, Pu) Preparation Bypassing An Metal Precursors: Access to Np/Pu Nonaqueous and Organometallic Complexes.

Direct comparison of homologous molecules provides a foundation from which to elucidate both subtle and patent changes in reactivity patterns, redox processes, and bonding properties across a series of elements. While trivalent molecular U chemistry is richly developed, analogous Np or Pu research has long been hindered by synthetic routes often requiring scarcely available metallic-phase source material, high-temperature solid-state reactions producing poorly soluble binary halides, or the use of pyrophoric reagents. The development of routes to nonaqueous Np/Pu from widely available precursors can potentially transform the scope and pace of research into actinide periodicity.

Isolation and characterization of a californium metallocene.

Californium (Cf) is currently the heaviest element accessible above microgram quantities. Cf isotopes impose severe experimental challenges due to their scarcity and radiological hazards. Consequently, chemical secrets ranging from the accessibility of 5f/6d valence orbitals to engage in bonding, the role of spin-orbit coupling in electronic structure, and reactivity patterns compared to other f elements, remain locked.

Th-Desferrioxamine: characterization of a fluorescent bacterial probe.

Diversifying our ability to guard against emerging pathogenic threats is essential for keeping pace with global health challenges, including those presented by drug-resistant bacteria. Some modern diagnostic and therapeutic innovations to address this challenge focus on targeting methods that exploit bacterial nutrient sequestration pathways, such as the desferrioxamine (DFO) siderophore used by () to sequester Fe. Building on recent studies that have shown DFO to be a versatile vehicle for chemical delivery, we show proof-of-principle that the Fe sequestration pathway can be used to deliver a potential radiotherapeutic.

Structural and Spectroscopic Comparison of Soft-Se vs. Hard-O Donor Bonding in Trivalent Americium/Neodymium Molecules.

Covalency is often considered to be an influential factor in driving An vs. Ln selectivity invoked by soft donor ligands. This is intensely debated, particularly the extent to which An /Ln covalency differences prevail and manifest as the f-block is traversed, and the effects of periodic breaks beyond Pu.

The H T dispersion curve of fentanyl citrate to identify NQR parameters.

We report the H T dispersion curve between 0 and 5 ​MHz for the synthetic opioid fentanyl citrate (CHNO). The structures in the curve can be used to estimate the N nuclear quadrupole resonance (NQR) frequencies of the material. Density functional theory predictions of the NQR parameters of several fentanyl citrate compounds are also reported.

Exploiting Functional Impurities for Fast and Efficient Incorporation of Manganese into Quantum Dots.

The incorporation of manganese (Mn) ions into Cd(Zn)-chalcogenide QDs activates strong spin-exchange interactions between the magnetic ions and intrinsic QD excitons that have been exploited for color conversion, sunlight harvesting, electron photoemission, and advanced imaging and sensing. The ability to take full advantage of novel functionalities enabled by Mn dopants requires accurate control of doping levels over a wide range of Mn contents. This, however, still represents a considerable challenge.

Design and implementation of a J-coupled spectrometer for multidimensional structure and relaxation detection at low magnetic fields.

In recent years, it has been realized that low and ultra-low field (mT-nT magnetic field range) nuclear magnetic resonance spectroscopy can be used for molecular structural analysis. However, spectra are often hindered by lengthy acquisition times or require large sample volumes and high concentrations. Here, we report a low field (50 μT) instrument that employs a linear actuator to shuttle samples between a 1 T prepolarization field and a solenoid detector in a laboratory setting.

Correction of Factor Effects for Simultaneous Collection of Elemental Analysis and Relaxation Times by Nuclear Magnetic Resonance.

A new method for measurement of elemental analysis by nuclear magnetic resonance (NMR) of unknown samples is discussed here as a quick and robust means to measure elemental ratios without the use of internal or external calibration standards. The determination of elemental ratios was done by normalizing the signal intensities by the frequency dependent quality factor () and the gyromagnetic ratios (γ) for each measured nucleus. The correction for the frequency dependence was found by characterizing the output signal of the probe as a function of the quality factor () and the frequency, and the correction for γ was discussed in a previous study.

Identification of the Formal +2 Oxidation State of Neptunium: Synthesis and Structural Characterization of {Np[CH(SiMe)]}.

We report a new formal oxidation state for neptunium in a crystallographically characterizable molecular complex, namely Np in [K(crypt)][NpCp″] [crypt = 2.2.2-cryptand, Cp″ = CH(SiMe)].

Identification of the Formal +2 Oxidation State of Plutonium: Synthesis and Characterization of {Pu[CH(SiMe)]}.

Over 70 years of chemical investigations have shown that plutonium exhibits some of the most complicated chemistry in the periodic table. Six Pu oxidation states have been unambiguously confirmed (0 and +3 to +7), and four different oxidation states can exist simultaneously in solution. We report a new formal oxidation state for plutonium, namely Pu in [K(2.

Synthesis of Acetone-Derived C , C , and C Carbon Scaffolds for Chemical and Fuel Applications.

A simple, inexpensive catalyst system (Amberlyst 15 and Ni/SiO -Al O ) is described for the upgrading of acetone to a range of chemicals and potential fuels. Stepwise hydrodeoxygenation of the produced ketones can yield branched alcohols, alkenes, and alkanes. An analysis of these products is provided, which demonstrates that this approach can provide a product profile of valuable bioproducts and potential biofuels.

Synthesis and characterization of potassium aryl- and alkyl-substituted silylchalcogenolate ligands.

Treatment of either triphenyl(chloro)silane or tert-butyldiphenyl(chloro)silane with potassium metal in THF, followed by addition of 18-crown-6, affords [K(18-crown-6)][SiPh3] () and [K(18-crown-6)][SiPh2(t)Bu] (), respectively, as the reaction products in high yield. Compounds and were fully characterized including by multi-nuclear NMR, UV/vis and IR spectroscopies. Addition of elemental chalcogen to either or , results in facile chalcogen insertion into the potassium-silicon bond to afford the silylchalcogenolates, [K(18-crown-6)][E-SiPh2R] (E = S, R = Ph (); E = Se, R = Ph (); E = Te, R = Ph (); E = S, R = (t)Bu (); E = Se, R = (t)Bu (); E = Te, R = (t)Bu ()), in moderate to good yield.

Coordination chemistry of 2,2'-biphenylenedithiophosphinate and diphenyldithiophosphinate with U, Np, and Pu.

New members of the dithiophosphinic acid family of potential actinide extractants were prepared: heterocyclic 2,2'-biphenylenedithiophosphinic acids of stoichiometry HS2P(R2C12H6) (R = H or (t)Bu). The time- and atom-efficient syntheses afforded multigram quantities of pure HS2P(R2C12H6) in reasonable yields (∼60%). These compounds differed from other diaryldithiophosphinic acid extractants in that the two aryl groups were connected to one another at the ortho positions to form a 5-membered dibenzophosphole ring.

Syntheses, structures, and (1)H, (13)C{(1)H} and (119)Sn{(1)H} NMR chemical shifts of a family of trimethyltin alkoxide, amide, halide and cyclopentadienyl compounds.

The synthesis and full characterization, including Nuclear Magnetic Resonance (NMR) data ((1)H, (13)C{(1)H} and (119)Sn{(1)H}), for a series of Me3SnX (X = O-2,6-(t)Bu2C6H3 (), (Me3Sn)N(2,6-(i)Pr2C6H3) (), NH-2,4,6-(t)Bu3C6H2 (), N(SiMe3)2 (), NEt2, C5Me5 (), Cl, Br, I, and SnMe3) compounds in benzene-d6, toluene-d8, dichloromethane-d2, chloroform-d1, acetonitrile-d3, and tetrahydrofuran-d8 are reported. The X-ray crystal structures of Me3Sn(O-2,6-(t)Bu2C6H3) (), Me3Sn(O-2,6-(i)Pr2C6H3) (), and (Me3Sn)(NH-2,4,6-(t)Bu3C6H2) () are also presented. These compiled data complement existing literature data and ease the characterization of these compounds by routine NMR experiments.

Ozonated graphene oxide film as a proton-exchange membrane.

Graphene oxide (GO) contains several chemical functional groups that are attached to the graphite basal plane and can be manipulated to tailor GO for specific applications. It is now revealed that the reaction of GO with ozone results in a high level of oxidation, which leads to significantly improved ionic (protonic) conductivity of the GO. Freestanding ozonated GO films were synthesized and used as efficient polymer electrolyte fuel cell membranes.

Solid-state and solution-state coordination chemistry of lanthanide(III) complexes with (pyrazol-1-yl)acetic acid.

As a precursor of carboxyl-functionalized task-specific ionic liquids (TSILs) for f-element separations, (pyrazol-1-yl)acetic acid (L) can be deprotonated as a functionalized pyrazolate anion to coordinate with hard metal cations. However, the coordination chemistry of L with f-elements remains unexplored. We reacted L with lanthanides in aqueous solution at pH = 5 and synthesized four lanthanide complexes of general formula [Ln(L)3(H2O)2]·nH2O (1, Ln = La, n = 2; 2, Ln = Ce, n = 2; 3, Ln = Pr, n = 2; 4, Ln = Nd, n = 1).

Spectroscopic characterization of alumina-supported bis(allyl)iridium complexes: site-isolation, reactivity, and decomposition studies.

The covalent attachment of tris(allyl)iridium to partially dehydroxylated gamma-alumina is found to proceed via surface hydroxyl group protonation of one allyl ligand to form an immobilized bis(allyl)iridium moiety, (=AlO)Ir(allyl)(2), as characterized by CP-MAS (13)C NMR, inductively coupled plasma-mass spectrometry, and Ir L(3) edge X-ray absorption spectroscopy. Extended X-ray absorption fine-structure (EXAFS) measurements taken on unsupported Ir(allyl)(3) and several associated tertiary phosphine addition complexes suggest that the eta(3)-allyl ligands generally account for an Ir-C coordination number of 2 rather than 3, with an average Ir-C distance of 2.16 A.

Fast photoreduction of a heme peptide encapsulated in nanostructured materials.

Microperoxidase-11 has been immobilized on siliceous materials MCM-41 and SBA-15 and on amino-functionalized SBA-15. Resonance Raman spectroscopy has provided solid evidence that the exogenous species occupy the pores of the mesoporous silica materials. Photoreduction of the microperoxidase-11 Fe(III) center has been observed to occur in the immobilized samples and results in a long-lived stable reduced heme.

Sensitivity considerations in polarization transfer and filtering using dipole-dipole couplings: implications for biomineral systems.

The robustness and sensitivities of different polarization-transfer methods that exploit heteronuclear dipole-dipole couplings are compared for a series of heterogeneous solid systems, including polycrystalline tetrakis(trimethylsilyl)silane (TKS), adamantane, a physical mixture of doubly (13)C,(15)N-enriched and singly (13)C-enriched polycrystalline glycine, and a powder sample of siliceous marine diatoms, Thalossiosira pseudonana. The methods were analyzed according to their respective frequency-matching spectra or resultant signal intensities. For a series of (13)C{(1)H} cross-polarization experiments, adiabatic passage Hartmann-Hahn cross-polarization (APHH-CP) was shown to have several advantages over other methods, including Hartmann-Hahn cross-polarization (HHCP), variable-amplitude cross-polarization (VACP), and ramped-amplitude cross-polarization (RACP).