Benjamin P. Warner

A SIMPLE PREPARATIVE ROUTE TO BIS(IMIDO)-URANIUM(VI) COMPLEXES BY THE DIRECT REDUCTIONS OF DIAZENES AND AZIDES

In clean, one-pot procedures, the uranium complex 1 reductively cleaves azides and azo compounds to generate bis(imido) derivatives [Eq. (a)]. This unusual reaction has not been observed previously in either the actinide series or with a metallocene complex.

Ytterbium trichloride-catalyzed allylation of aldehydes with allyltrimethylsilane

Abstract Ytterbium chloride (YbCl 3 ) is found to be an effective catalyst for the allylation of both aromatic and aliphatic aldehydes using allyltrimethylsilane.

Plutonium(III)-catalyzed Meerwein–Ponndorf–Verley reactions

Abstract The reactivity of Th(IV), U(III), U(IV), Pu(III) and Pu(IV) iso -propoxide in the Meerwein–Ponndorf–Verley reduction of ketones by iso -propanol have been examined. Plutonium(III) iso -propoxide is found to be an effective catalyst for the reduction of a range of substituted aryl-alkyl ketones, while An(IV) iso -propoxides (An=Th, U, Pu) are found to be inactive. U(III) was found to oxidize under the reaction conditions to a U(IV) complex, which was also catalytically inactive.

Rapid identification of metal-binding peptoid oligomers by on-resin X-ray fluorescence screening.

N‐Substituted glycine peptoid oligomers have recently attracted attention for their metal binding capabilities. Due to their efficient synthesis on solid phase, peptoids are well suited for generation of compound libraries, followed by screening for molecular recognition and other diverse functional attributes. Ideally, peptoids could be simultaneously screened for binding to a number of metal species. Here, we demonstrate the use of bench‐top X‐ray fluorescence (XRF) instrumentation to screen rapidly, on solid support, a library of peptoid oligomers incorporating metal‐binding functionalities. A subset of the peptoid sequences exhibited significant metal binding capabilities, including a peptoid pentamer and a nonamer that were shown to selectively bind nickel. The binding capabilities were validated by colorimetric assay and by depletion of Ni2+ ion concentration from solution, establishing bench‐top XRF as a rapid, practicable high‐throughput screening technique for peptoid oligomers. This protocol will facilitate discovery of metallopeptoids with unique material properties.

Ytterbium Trichloride-Catalyzed Diels-Alder Reactions of Unactivated Dienes

Abstract Ytterbium chloride (YbCl3) is an effective and reusable catalyst for Diels-Alder reactions of unactivated dienes with α,β-unsaturated ketones and aldehydes at room temperature, leading to products with high regio- and stereoselectivities.

An ultra high throughput, double combinatorial screening method of peptide-metal binding

An effective ultra-high throughput, double combinatorial method of screening potential selective ligands based upon oligopeptides is described. This rapid screening of bead-based libraries by Micro X-ray Fluorescence (MXRF) was used to identify selective chelating agents for metals that may be found in radioactive dispersive devices (RDDs). The method has proven to be a powerful tool to rapidly and quantitatively screen metal–ligand interactions. It is a tag-free, sensitive technique, which in a combinatorial approach with peptide libraries (e.g. varying charge, length, hydrophobicity, ligand elements etc.), provides a rapid and quantitative means for identifying metal–ligand interactions.

A high throughput screening method for the selection of zeolites for binding cations

An effective high throughput screening technique is described for the rapid analysis of zeolites as binding agents for cationic sequestration.

Lewis base binding affinities and redox properties of plutonium complexes

As part of the actinide molecular science competency development effort, the initial goal of this work is to synthesize and investigate several series of complexes, varying by actinide metal, ligand set, and oxidation state. We are examining the reactivity of plutonium and neptunium organometallic complexes to elucidate fundamental chemical parameters of the metals. These reactions will be compared to those of the known corresponding uranium complexes in order to recognize trends among the actinide elements and to document differences in chemical behavior.

Micro x-ray fluorescence as a high throughput screening method for metal chelating compounds

Micro X-ray Fluorescence (MXRF) has proven to be a powerful tool in the rapid and quantitative means of screening oliogpeptides. MXRF is a non-destructive method of analysis, which can detect elemental composition of a sample by measuring its characteristic X-ray emission wavelengths or energies. An effective high throughput screening technique is described for the rapid screening of bead-based libraries by MXRF in order to identify suitable chelating agents that will bind metals found in radioactive dispersive devices. It is a sensitive technique which in conjunction with the wide range of chemistry inherent in peptide libraries (e.g. varying charge, length, hydrophobicity, aromaticity etc.), provides a rapid and quantitative means for screening chelator-ion binding. The method involves the selection of a suitable library of ligands; in this case it is a bead-based library of peptides. The library is exposed to the cation of interest and immobilized on to a microarray. The array is then analyzed by MXRF enabling rapid identification of chelating agents. This enables the screening of approximately 27,500 sequences per day. Initial experiments carried out successfully identified sequences that are selective for Co under certain binding conditions. This involved the screening of 8,400 sequences in adverse environmental conditions containing possible interferences (e.g. Ca, Fe, Al, Cs, Ir), which could be encountered in our application.

High-throughput screening of metal chelating compounds

An effective high throughput screening technique is described for the rapid analysis of solid-supported libraries to identify selective chelating agents for metals, focusing on those possibly present in radioactive dispersal devices. Micro X-ray Fluorescence (MXRF) is the method of choice. MXRF is a rapid and sensitive technique which allows the measurement of metal-chelator complexes without significant sample preparation. For this study we have employed commercial peptide libraries and have examined factors such as side-chain charge, oligopeptide length, hydrophobicity, and aromaticity in relation to metal binding. MXRF provides a rapid and quantitative means for screening chelator-ion binding. Initial experiments carried out successfully identified sequences that are selective for Co under certain binding conditions containing possible interferences (e.g. Ca, Fe, Al, Cs, Ir), which could be encountered in our application.