201
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Papatriantafyllopoulou C, Wernsdorfer W, Abboud KA, Christou G. Mn21Dy Cluster with a Record Magnetization Reversal Barrier for a Mixed 3d/4f Single-Molecule Magnet. Inorg Chem 2010; 50:421-3. [DOI: 10.1021/ic102378u] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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202
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Kuppuswamy S, Ghiviriga I, Abboud KA, Veige AS. Activation of an Aryl C−H Bond Converts Chelating Diphenolate Ligands Bound to Zirconium into Trianionic Pincer Ligands: σ-Donor Ligand Effects versus Thermolysis. Organometallics 2010. [DOI: 10.1021/om100732d] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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203
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Rossi MB, Abboud KA, Alborés P, Baraldo LM. Structural and Spectroscopic Evidence of Strong Electronic Delocalization through a Cyanido Bridge in a Mixed‐Valence Os–Ru Complex. Eur J Inorg Chem 2010. [DOI: 10.1002/ejic.201000912] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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204
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Sarkar S, Culver JA, Peloquin AJ, Ghiviriga I, Abboud KA, Veige AS. Primary Carbon-Nitrogen Bond Scission and Methyl Dehydrogenation across a WW Multiple Bond. Angew Chem Int Ed Engl 2010; 49:9711-4. [DOI: 10.1002/anie.201004233] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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205
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Sarkar S, Culver JA, Peloquin AJ, Ghiviriga I, Abboud KA, Veige AS. Primary Carbon-Nitrogen Bond Scission and Methyl Dehydrogenation across a WW Multiple Bond. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201004233] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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206
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Kwan JC, Ratnayake R, Abboud KA, Paul VJ, Luesch H. Grassypeptolides A-C, cytotoxic bis-thiazoline containing marine cyclodepsipeptides. J Org Chem 2010; 75:8012-23. [PMID: 21047144 PMCID: PMC2993180 DOI: 10.1021/jo1013564] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
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Grassypeptolides A−C (1−3), a group of closely related bis-thiazoline containing cyclic depsipeptides, have been isolated from extracts of the marine cyanobacterium Lyngbya confervoides. Although structural differences between the analogues are minimal, comparison of the in vitro cytotoxicity of the series revealed a structure−activity relationship. When the ethyl substituent of 1 is changed to a methyl substituent in 2, activity is only slightly reduced (3−4-fold), whereas inversion of the Phe unit flanking the bis-thiazoline moiety results in 16−23-fold greater potency. We show that both 1 and 3 cause G1 phase cell cycle arrest at lower concentrations, followed at higher concentrations by G2/M phase arrest, and that these compounds bind Cu2+ and Zn2+. The three-dimensional structure of 2 was determined by MS, NMR, and X-ray crystallography, and the structure of 3 was established by MS, NMR, and chemical degradation. The structure of 3 was explored by in silico molecular modeling, revealing subtle differences in overall conformation between 1 and 3. Attempts to interconvert 1 and 3 with base were unsuccessful, but enzymatic conversion may be possible and could be a novel form of activation for chemical defense.
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207
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Taguchi T, Wernsdorfer W, Abboud KA, Christou G. Mn8 and Mn16 Clusters from the Use of 2-(Hydroxymethyl)pyridine, and Comparison with the Products from Bulkier Chelates: A New High Nuclearity Single-Molecule Magnet. Inorg Chem 2010; 49:10579-89. [DOI: 10.1021/ic101594d] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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208
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Seo H, Roberts BP, Abboud KA, Merz KM, Hong S. Novel Acyclic Diaminocarbene Ligands with Increased Steric Demand and Their Application in Gold Catalysis. Org Lett 2010; 12:4860-3. [DOI: 10.1021/ol102018z] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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209
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Hirsch-Weil D, Abboud KA, Hong S. Isoquinoline-based chiral monodentate N-heterocyclic carbenes. Chem Commun (Camb) 2010; 46:7525-7. [PMID: 20835472 DOI: 10.1039/c0cc02211j] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
C(1)-symmetric isoquinoline-based chiral diaminocarbene ligands (MIQ) have been developed to block three quadrants of the metal coordination sphere, complementing C(2)-symmetric biisoquinoline-based ligands (BIQ). MIQ-Cu complexes catalyzed conjugate borylation of various α,β-unsaturated amides in good yields (82-99%) and enantioselectivities (75-87% ee).
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210
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Denomme DR, Dumbris SM, Hyatt IFD, Abboud KA, Ghiviriga I, McElwee-White L. Synthesis and Electronic Structure of Tetrakis(η3-phenylpropargyl)zirconium. Organometallics 2010. [DOI: 10.1021/om100405n] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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211
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Kuppuswamy S, Peloquin AJ, Ghiviriga I, Abboud KA, Veige AS. Synthesis and Characterization of Tungsten(VI) Alkylidene Complexes Supported by an [OCO]3− Trianionic Pincer Ligand: Progress towards the [tBuOCO]W≡CC(CH3)3 Fragment. Organometallics 2010. [DOI: 10.1021/om100189b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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212
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Stamatatos TC, Abboud KA, Christou G. A Family of 3-D Coordination Polymers Composed of Mixed-Valence Mn6 Octahedra within Na4 Tetrahedra. J CLUST SCI 2010. [DOI: 10.1007/s10876-010-0324-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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213
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Bergeron RJ, Bharti N, Wiegand J, McManis JS, Singh S, Abboud KA. The impact of polyether chain length on the iron clearing efficiency and physiochemical properties of desferrithiocin analogues. J Med Chem 2010; 53:2843-53. [PMID: 20232803 DOI: 10.1021/jm9018146] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
(S)-2-(2,4-Dihydroxyphenyl)-4,5-dihydro-4-methyl-4-thiazolecarboxylic acid (2) was abandoned in clinical trials as an iron chelator for the treatment of iron overload disease because of its nephrotoxicity. However, subsequent investigations revealed that replacing the 4'-(HO) of 2 with a 3,6,9-trioxadecyloxy group, ligand 4, increased iron clearing efficiency (ICE) and ameliorated the renal toxicity of 2. This compelled a closer look at additional polyether analogues, the subject of this work. The 3,6,9,12-tetraoxatridecyloxy analogue of 4, chelator 5, an oil, had twice the ICE in rodents of 4, although its ICE in primates was reduced relative to 4. The corresponding 3,6-dioxaheptyloxy analogue of 2, 6 (a crystalline solid), had high ICEs in both the rodent and primate models. It significantly decorporated hepatic, renal, and cardiac iron, with no obvious histopathologies. These findings suggest that polyether chain length has a profound effect on ICE, tissue iron decorporation, and ligand physiochemical properties.
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214
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Sarkar S, McGowan KP, Culver JA, Carlson AR, Koller J, Peloquin AJ, Veige MK, Abboud KA, Veige AS. NCN Trianionic Pincer Ligand Precursors: Synthesis of Bimetallic, Chelating Diamide, and Pincer Group IV Complexes. Inorg Chem 2010; 49:5143-56. [DOI: 10.1021/ic100232s] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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215
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Liu TF, Stamatatos TC, Abboud KA, Christou G. An alcoholysis route to a Cu16 cluster, and the influence of the alcohol. Dalton Trans 2010; 39:3554-6. [PMID: 20354607 DOI: 10.1039/c002925b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A systematic investigation of the alcoholysis of copper(II) pivalate (piv(-)) solutions has led to a series of Cu(2), Cu(6), and Cu(16) products, depending on the alcohol used as solvent. When Pr(n)OH or Bu(n)OH was employed, the products were the clusters [Cu(16)O(4)(OH)(4)(OR)(8)(piv)(12)(ROH)] (R = Pr(n), Bu(n)) that are almost isostructural. The Cu(16) clusters are antiferromagnetically-coupled with an S = 0 spin ground state.
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216
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Lampropoulos C, Stamatatos TC, Manos MJ, Tasiopoulos AJ, Abboud KA, Christou G. New Mixed-Valence MnII/III6 Complexes Bearing Oximato and Azido Ligands: Synthesis, and Structural and Magnetic Characterization. Eur J Inorg Chem 2010. [DOI: 10.1002/ejic.200901013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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217
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Snead DR, Inagaki S, Abboud KA, Hong S. Bis(2-alkylpyrrolidin-1-yl)methylidenes as Chiral Acyclic Diaminocarbene Ligands. Organometallics 2010. [DOI: 10.1021/om901112n] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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218
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O'Reilly M, Falkowski JM, Ramachandran V, Pati M, Abboud KA, Dalal NS, Gray TG, Veige AS. Catalytic aerobic oxidation by a trianionic pincer Cr(III)/Cr(V) couple. Inorg Chem 2010; 48:10901-3. [PMID: 19894679 DOI: 10.1021/ic9019469] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Aerobic oxidation that incorporates both O atoms into a substrate (PPh(3)) is achieved by employing a Cr(III)/Cr(V)[triple bond]O catalytic couple. A terphenyl trianionic pincer ligand stabilizes a high oxidation state Cr(V)[triple bond]O complex, and both the reduced (Cr(III), IR/X-ray) and oxidized (Cr(V)[triple bond]O, electron paramagnetic resonance/IR/X-ray) participants in the catalytic cycle are characterized.
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219
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Lampropoulos C, Redler G, Data S, Abboud KA, Hill S, Christou G. Binding of Higher Alcohols onto Mn12 Single-Molecule Magnets (SMMs): Access to the Highest Barrier Mn12 SMM. Inorg Chem 2010; 49:1325-36. [DOI: 10.1021/ic901480y] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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220
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Taguchi T, Daniels MR, Abboud KA, Christou G. Mn4, Mn6, and Mn11 clusters from the use of bulky diphenyl(pyridine-2-yl)methanol. Inorg Chem 2010; 48:9325-35. [PMID: 19728691 DOI: 10.1021/ic901306k] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The synthesis, crystal structure, and magnetochemical characterization are reported of three new Mn clusters [Mn(4)O(2)(O(2)CBu(t))(5)(dphmp)(3)] (1), [Mn(6)O(4)(OMe)(2)(O(2)CPh)(4)(dphmp)(4)] (2), and [Mn(11)O(7)(OMe)(7)(O(2)CPh)(7)(dphmp)(4)(MeOH)(2)] (3). They were obtained from the use of diphenyl(pyridine-2-yl)methanol (dphmpH), a bulkier version of the 2-(hydroxymethyl)pyridine (hmpH) reagent commonly employed previously in Mn chemistry. The reaction of dphmpH with MnCl(2) x 4 H(2)O and NaO(2)CBu(t) in MeCN/MeOH (30 mL, 5:1 v/v) led to the isolation of tetranuclear complex 1, whereas the analogous reaction with NaO(2)CPh gave hexanuclear complex 2. When the 5:1 solvent ratio in the latter reaction was changed to 1:29, the isolated product was now undecanuclear complex 3. Complexes 1-3 all possess rare or unprecedented Mn(x) topologies: Complex 1 possesses a [Mn(4)(mu(3)-O)(2)](8+) (4 Mn(III)) butterfly core, one edge of which is additionally bridged by an alkoxide arm of a dphmp(-) chelate; complex 2 possesses a [Mn(6)(mu(4)-O)(2)(mu(3)-O)(2)(mu(3)-OMe)(2)](8+) (6 Mn(III)) core with a face-sharing double cubane topology; and complex 3 (Mn(II), 10 Mn(III)) possesses a [Mn(4)(mu(4)-O)(3)(mu(3)-OMe)](5+) cubane unit, attached on one side to a Mn(II) atom by a mu(4)-O atom and alkoxide groups, and on the other side to a [Mn(5)(mu(4)-O)(mu(3)-O)(3)(mu(3)-OMe)(mu-OR)(3)](3+) unit consisting of three face-sharing defective cubanes linked to an additional Mn(III) atom by a mu(3)-O atom. Solid-state dc and ac magnetic susceptibility measurements on 1-3 establish that they possess S = 0, 3, and 5/2 ground states, respectively. ac susceptibility studies on 2 and 3 reveal weak non-zero frequency-dependent out-of-phase (chi(M)'') signals at temperatures below 3 K, possibly indicative of single-molecule magnets with very small barriers. The combined results demonstrate a ligating difference between bulky dphmp(-) and hmp(-), and the resulting usefulness of the former to provide access to a variety of Mn(x) molecular species not known with the latter.
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221
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Taguchi T, Thompson MS, Abboud KA, Christou G. Unusual Fe9 and Fe18 structural types from the use of 2,6-pyridinedimethanol in FeIII cluster chemistry. Dalton Trans 2010; 39:9131-9. [DOI: 10.1039/c0dt00635a] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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222
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Lowry RJ, Jan MT, Abboud KA, Ghiviriga I, Veige AS. The next generation of C2-symmetric ligands: A di-N-heterocyclic carbene (NHC) ligand and the synthesis and X-ray characterization of mono- and dinuclear rhodium(I) and iridium(I) complexes. Polyhedron 2010. [DOI: 10.1016/j.poly.2009.06.075] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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223
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Jeletic MS, Ghiviriga I, Abboud KA, Veige AS. A new chiral di-N-heterocyclic carbene (NHC) cyclophane ligand and its application in palladium enantioselective catalysis. Dalton Trans 2010; 39:6392-4. [DOI: 10.1039/c0dt00268b] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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224
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Taguchi T, Wernsdorfer W, Abboud KA, Christou G. Mn7 and Mn12 Clusters From Use of 2-(Pyridine-2-yl)propan-2-ol: A New Half-Integer Single-Molecule Magnet. Inorg Chem 2009; 49:199-208. [DOI: 10.1021/ic901741n] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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225
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Shen DE, Abboud KA, Reynolds JR. Novel Bis-arylPheDOT Synthons for Electrochromic Polymers. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2009. [DOI: 10.1080/10601320903394389] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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