Scott D. Bunge

Growth and morphology of cadmium chalcogenides: the synthesis of nanorods, tetrapods, and spheres from CdO and Cd(O2CCH3)2

In this work, we investigated the controlled growth of nanocrystalline CdE (E = S, Se, and Te) via the pyrolysis of CdO and Cd(O2CCH3)2 precursors, at the specific Cd to E mole ratio of 0.67 to 1. The experimental results reveal that while the growth of CdS produces only a spherical morphology, CdSe and CdTe exhibit rod-like and tetrapod-like morphologies of temporally controllable aspect ratios. Over a 7200 s time period, CdS spheres grew from 4 nm (15 s aliquot) to 5 nm, CdSe nanorods grew from dimensions of 10.8 × 3.6 nm (15 s aliquot) to 25.7 × 11.2 nm, and CdTe tetrapods with arms 15 × 3.5 nm (15 s aliquot) grew into a polydisperse mixture of spheres, rods, and tetrapods on the order of 20 to 80 nm. Interestingly, long tracks of self-assembled CdSe nanorods (3.5 × 24 nm) of over one micron in length were observed. The temporal growth for each nanocrystalline material was monitored by UV-VIS spectroscopy, transmission electron spectroscopy, and further characterized by powder X-ray diffraction. This study has elucidated the vastly different morphologies available for CdS, CdSe, and CdTe during the first 7200 s after injection of the desired chalcogenide.

A tetradecanuclear copper dimeric macrocyclic complex with a body-centred heptanuclear core-structure and magnetism

2,6-Diformyl-4-methylphenol and 1,3-diamino-2-hydroxypropane template condense in the presence of Cu(NO(3))(2) and azide to produce a 3 : 3 macrocyclic ring containing an unprecedented grouping of seven copper(ii) ions within the macrocyclic cavity, with the seventh metal completing a body-centred heptanuclear lattice.

Anhydrous solution synthesis of germanium nanocrystals from the germanium(II) precursor Ge[N(SiMe3)2]2

A convenient, simple, single-source solution synthesis of Ge nanocrystals via thermal reduction of Ge(II) precursor Ge[N(SiMe3)2]2 in a non-coordinating solvent at 300 degrees C and 1 atm Ar is described.

Membrane Receptor Mapping: The Membrane Topography of FceRI Signaling

Ligand binding to membrane receptors initiates cascades of biochemical events leading to physiological responses. Hundreds of proteins and lipids are implicated in signaling networks and programs in genomics and proteomics are continuously adding new components to the signaling “parts lists”. Here, we generate high resolution maps of signaling networks using cytoplasmic face-up membrane sheets that can be labeled with inununogold probes (3–10 nm) and imaged in the transmission electron microscope. Our model system is the mast cell and we focus on mapping the topography of the high affinity IgE receptor, FceRI, its associated tyrosine kinases, Lyn and Syk, and the signaling proteins that propagate signals from these kinases. Crosslinked receptors and their signaling partners segregate during signaling to multiple, dynamic membrane domains, including a transient FceRI-Lyn domain and at least two other distinct domains, one characterized by the presence of receptor, Syk and multiple signaling proteins, but not Lyn (primary signaling domains), and one characterized by the presence of LAT and PLCγl but not receptor (secondary signaling domains). PI 3-kinase associates with both primary and secondary signaling domains and may help to recruit specific signaling proteins through the local remodeling of inositol phospholipids. The lipid raft markers, GM1 and Thy-1, fail to localize in native membrane sheets either with each other or with signaling domains. We introduce new probes to localize multiple signaling molecules on the same membrane sheet and new computational tools to capture and analyze their topographical relationships. In the future, we expect that high resolution maps of signaling networks will be integrated with chemical kinetic analyses, with cell fractionation data and with a range of real-time fluorescence measurements, into mathematical models with power to predict mechanisms that regulate the efficiency, specificity, amplitude and duration of signaling pathways.

Synthesis and characterization of InP and InN colloidal quantum dots

InP quantum dots (QDs) with zinc blende structure and InN QDs with hexagonal structure were synthesized from appropriate organometallic precursors in a noncoordinating solvent using myristic acid as a ligand. The QDs were characterized by TEM, the associated energy dispersive spectroscopy (EDS), electron diffraction, and steady state UV-VIS optical absorption and photoluminescence spectroscopy. To our best knowledge, this paper reports synthesis of InN colloidal quantum dots for the first time.

Synthesis, structural characterization and dynamic behavior of Group 12 metals containing the sterically hindered ligand [N(t-Bu)CH(t-Bu)CHN-t-Bu]− ☆

Abstract The reaction of two molar equivalents of the alkyl-substituted (E)-4-lithio-1,4-diazabut-1-ene, Li[μ-N(t-Bu)CH(t-Bu)CHN-t-Bu], with zinc dichloride, cadmium dibromide, or mercury dibromide in diethyl ether yields zinc M{[μ-N(t-Bu)CH(t-Bu)CHN-t-Bu][N(t-Bu)CH(t-Bu)CHN-t-Bu]}, [M=Zn (1)], cadmium M[μ-N(t-Bu)CH(t-Bu)CHN-t-Bu]2, [M=Cd (2)], or mercury M{[μ-N(t-Bu)CH(t-Bu)CHN-t-Bu][N(t-Bu)CH(t-Bu)CHN-t-Bu]} [M=Hg (3)], respectively, as colorless crystals. In the solid state, the central metal of 2 possesses a coordination number of four; compounds 1 and 3 display the rather unusual coordination number of three.

Synthesis and characterization of InP and InN colloidal nanocrystals

We report on colloidal synthesis of InP and InN nanocrystals (NCs) from organometallic precursors in a noncoordinating solvent using myristic acid as a ligand. The results of NC structural and optical characterization are presented.