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Alan Davison

Bio: Alan Davison is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Denticity & Ligand. The author has an hindex of 42, co-authored 207 publications receiving 5783 citations. Previous affiliations of Alan Davison include Brigham and Women's Hospital & Suffolk University.


Papers
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Journal ArticleDOI
TL;DR: The 1,1′-dilithioferrocene can be used in situ, or when isolated as the pyrophoric adduct [(C 5 H 4 Li) 2 Fe]·TMEDA, to prepare the following complexes in high yields: ferrocene-1, 1, 1′-bis(dimethylarsine) (Fdma), ferrocenophane, Fdpa, Fdt, Fydioxene, and Fdmp, which can be converted quantitatively to Fdt by reduction with lithium aluminum hydr

369 citations

Journal Article
TL;DR: It is proposed that the plasma and mitochondrial membrane potentials play a major role in the uptake of the cationic compound hexakis(2-methoxyisobutylisonitrile)-technetium-99m, which exhibits interesting tumor cell interaction characteristics with promise for in vivo tumor imaging.
Abstract: Uptake of the cationic compound hexakis(2-methoxyisobutylisonitrile)-technetium-99m ([99mTc]MIBI) was examined in nine human tumor cell lines. The concentration of [99mTc]MIBI after a 1-h incubation with the compound varies from 5 to 28% of the activity in the external medium. In contrast, normal V79 cells (Chinese hamster lung fibroblasts) and human peripheral blood mononuclear cells exhibit a minimal uptake of less than 2% of the activity in the medium. Kinetic experiments with SW-13 cells indicate a rapid uptake over time (t½ of 10 min) until a steady state is approached whose concentration appears directly correlated with the extracellular concentration of [99mTc]MIBI with no evidence of saturation over the range tested (10-12-10-9m). [99mTc]MIBI is taken up by a temperature dependent process that is restricted to living cells. Microautoradiography demonstrates that [99mTc]MIBI is clustered in the cytoplasm around the nucleus. Given that depolarizing the plasma membrane potential in high K+ buffer results in lowering the uptake of [99mTc]MIBI and that alteration of the mitochondrial membrane potential with valinomycin or nigericin induces, respectively, a significant decrease or increase of [99mTc]MIBI uptake, we propose that the plasma and mitochondrial membrane potentials play a major role in the uptake. These data suggest that the γ emitter [99mTc]MIBI exhibits interesting tumor cell interaction characteristics with promise for in vivo tumor imaging.

261 citations

Journal ArticleDOI
TL;DR: Biological distribution and imaging data in animals indicate that certain members of this class of cationic technetium compounds may be effective for cardiac imaging in man.

198 citations

Journal ArticleDOI
TL;DR: The benzoyl-protected dimercaptodiamides (PhCOS(CH/sub 2)/sub n/CONH)/sub 2/X (n = 1, X = (CH/ sub 2/)/sub 3/, and 0-C/sub 6/H/sub 4/) have been synthesized as discussed by the authors.
Abstract: The benzoyl-protected dimercaptodiamides (PhCOS(CH/sub 2/)/sub n/CONH)/sub 2/X (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and 0-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/ and (CH/sub 2/)/sub 3/) have been synthesized. From these, via the sodium dithionite reduction of TcO/sub 4//sup -/ in base, the technetium complexes (TcO(S(CH/sub 2/)/sub n/CONXNCO(CH/sub 2/)/sub n/S))/sup -/ (n = 1, X = (CH/sub 2/)/sub 2/, (CH/sub 2/)/sub 3/, and o-C/sub 6/H/sub 4/; n = 2, X = (CH/sub 2/)/sub 2/) have been prepared. The synthesis and characterization of the complexes, and their precursors, are presented, and the radiopharmaceutical applicability is discussed.

142 citations

Journal ArticleDOI
TL;DR: In this paper, the pertechnetate ion with aqueous sodium dithionite was reduced to hexakis(alkyl isocyanide) technetium(I) hexafluorophosphate (Tc(CNR)/sub 6/)PF/sub 6/ (where R = tert-butyl, methyl, cyclohexyl, and phenyl), and the complexes were characterized by elemental analysis, optical, ir, and /sup 1/H NMR spectroscopy, conductance, cyclic voltammetry, and field des
Abstract: The complexes, hexakis(alkyl isocyanide) technetium(I) hexafluorophosphate (Tc(CNR)/sub 6/)PF/sub 6/ (where R = tert-butyl, methyl, cyclohexyl, and phenyl), have been prepared by reduction of the pertechnetate ion with aqueous sodium dithionite (Na/sub 2/S/sub 2/O/sub 4/) in the presence of the isocyanide ligands. These complexes have been characterized by elemental analysis, optical, ir, and /sup 1/H NMR spectroscopy, conductance, cyclic voltammetry, and field desorption mass spectrometry.

140 citations


Cited by
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Journal ArticleDOI
01 Apr 1988-Nature
TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

9,929 citations

Journal ArticleDOI
TL;DR: This review will focus mainly on the new methods that have appeared in the literature since 1989 for stereoselective cyclopropanation reactions from olefins: the halomethylmetal-mediated cycloalkane reactions, the transition metal-catalyzed decomposition of diazo compounds, and the nucleophilic addition-ring closure sequence.
Abstract: Organic chemists have always been fascinated by the cyclopropane subunit.1 The smallest cycloalkane is found as a basic structural element in a wide range of naturally occurring compounds.2 Moreover, many cyclopropane-containing unnatural products have been prepared to test the bonding features of this class of highly strained cycloalkanes3 and to study enzyme mechanism or inhibition.4 Cyclopropanes have also been used as versatile synthetic intermediates in the synthesis of more functionalized cycloalkanes5,6 and acyclic compounds.7 In recent years, most of the synthetic efforts have focused on the enantioselective synthesis of cyclopropanes.8 This has remained a challenge ever since it was found that the members of the pyrethroid class of compounds were effective insecticides.9 New and more efficient methods for the preparation of these entities in enantiomerically pure form are still evolving, and this review will focus mainly on the new methods that have appeared in the literature since 1989. It will elaborate on only three types of stereoselective cyclopropanation reactions from olefins: the halomethylmetal-mediated cyclopropanation reactions (eq 1), the transition metal-catalyzed decomposition of diazo compounds (eq 2), and the nucleophilic addition-ring closure sequence (eqs 3 and 4). These three processes will be examined in the context of diastereoand enantiocontrol. In the last section of the review, other methods commonly used to make chiral, nonracemic cyclopropanes will be briefly outlined.

1,426 citations

Book ChapterDOI
K. Wade1
TL;DR: In this paper, the borane-carborane structural pattern has been studied in a wide range of other compounds, including metal clusters, metal-hydrocarbon 7∼ complexes, and various neutral or charged hydrocarbons.
Abstract: Publisher Summary This is one of two articles in this volume that is concerned with the borane-carborane structural pattern. In the other, Williams has shown how the pattern reflects the coordination number preferences of the various atoms involved. The purpose of the present article is to note some bonding implications of the pattern, and to show its relevance to a wide range of other compounds, including metal clusters, metal-hydrocarbon 7∼ complexes, and various neutral or charged hydrocarbons. Boranes and carboranes may be regarded as cluster compounds in the sense defined by Cotton; they contain a finite group or skeleton of atoms held together entirely, mainly, or at least to a significant extent by bonding directly between those atoms, even though some other atoms may be associated intimately with the cluster. Examples of their structural pattern, however, can be found far beyond the confines of what is normally regarded as cluster chemistry, so this survey includes many systems not commonly referred to as clusters.

1,235 citations

Journal ArticleDOI
TL;DR: The history of the first generation PDT agent hematoporphyrin derivative is described in detail in this article, where the optical spectra of porphyrins and chlorins are analyzed.

916 citations