9 research outputs found
Josiah Parsons Cooke Jr.: Epistemology in the Service of Science, Pedagogy, and Natural Theology
Josiah Parsons Cooke established chemistry education at Harvard University, initiated an atomic weight research program, and broadly impacted American chemical education through his students, the introduction of laboratory instruction, textbooks, and influence on Harvard's admissions requirements. The devoutly Unitarian Cooke also articulated and defended a biogeochemical natural theology, which he defended by arguing for commonalities between the epistemologies of science and religion. Cooke's pre-Mendeleev classification scheme for the elements and atomic weight research were motivated by his interest in numerical order in nature, which reflected his belief in a divine lawgive
Enantiomer-Specific Binding of Ruthenium(II) Molecular Wires by the Amine Oxidase of Arthrobacter globiformis
The copper amine oxidase from Arthrobacter globiformis (AGAO) is reversibly inhibited by molecular wires comprising a Ru(II) complex head group and an aromatic tail group joined by an alkane linker. The crystal structures of a series of Ru(II)-wireâAGAO complexes differing with respect to the length of the alkane linker have been determined. All wires lie in the AGAO active-site channel, with their aromatic tail group in contact with the trihydroxyphenylalanine quinone (TPQ) cofactor of the enzyme. The TPQ cofactor is consistently in its active (âoff-Cuâ) conformation, and the side chain of the so-called âgateâ residue Tyr296 is consistently in the âgate-openâ conformation. Among the wires tested, the most stable complex is produced when the wire has a â(CH_2)_4â linker. In this complex, the Ru(II)(phen)(bpy)_2 head group is level with the protein molecular surface. Crystal structures of AGAO in complex with optically pure forms of the C4 wire show that the linker and head group in the two enantiomers occupy slightly different positions in the active-site channel. Both the Î and Î isomers are effective competitive inhibitors of amine oxidation. Remarkably, inhibition by the C4 wire shows a high degree of selectivity for AGAO in comparison with other copper-containing amine oxidases
P450 Electron Transfer Reactions
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Cyanide Compounds
Chapter 4, âCyanide Compounds,â illustrates an explosively developing research theme in which the cyanide ligand is used as a linking agent for the designed assembly of polynuclear metal complexes. Syntheses of several basic building blocks, such as K3[Cr(CN)6],Cr(Me3tacn)(CN)3,K4[Mo(CN)8],Na[W(CO)5CN],K[CpFe(CO)(CN)2],[NEt4][Cp*Rh(CN)3],[Fe4(bpy)8(ÎŒ-CN)4][PF6]4,. are given here. These units may be used in several ways to construct polynuclear compounds. One approach involves a hexacyanometalate core decorated with peripheral metal centers, e.g., [{Cu(tpa)(CN)}6Fe][ClO4]8. or [Cr{CNNi(tetren)}6][ClO4]9. An octacyanometalate unit can lead to higher nuclearity condensed compounds, as in [Co{Co(MeOH)3}8(ÎŒ-CN)30{Mo(CN)3}6]. Alternatively, a cluster core may be substituted with cyano complexes as ligands, as in [PPh4]2[Fe4S4{NCW(CO)5}4]. If there are two cis cyano ligands on the building block, then quadrilateral or square structures often result, as in {CpFe(CO(ÎŒ-CN)2Cu(PCy3)}2 and [Fe2Cu2(bpy)6(ÎŒ-CN)4][PF6]4 However, if there are three adjacent cyano ligands, then cubic cages may be constructed as in [(CpCo)4(Cp*Rh)4(ÎŒ-CN)12][PF6]4