A. David Baker

SALT DEPENDENCE OF BINDING OF Δ- and Λ-Ru(2, 2′-bypyridine)2ppz (+2) AND A CHIRAGEN ANALOG WITH CALF THYMUS DNA: UNPREDICTIBILITY OF ENANTIOSELECTIVE BINDING TO DNA

Abstract Fluorescence techniques have been used to measure binding constants with calf thymus DNA for both enantiomers of Ru(bpy)2ppz(+2) as well as a (+)-chiragen[6] complex of ruthenium(II) of Δ configuration, which has ppz as a third ligand. The configuration of the more strongly binding enantiomer of Ru(bpy)2ppz(+2) is unambiguously assigned as Λ (and not Δ as previously assumed), by comparison of the circular dichroism spectrum of the (+)-chiragen[6] complex of ruthenium(II) with ppz to the CD spectra of the bipyridine complexes. This assignment is also consistent with exciton theory of the circular dichroism spectra of such complexes. Binding constants for each enantiomer as well as the (+)-chiragen[6] complex are reported, and serve to quantitate the chiral discrimination of binding to DNA. Analysis of the sodium ion concentration dependence of the binding constants using polyelectrolyte theory indicates that the binding is largely electrostatic in nature. The non-electrostatic contribution (Kt°) a...

The He(I) photoelectron spectra of some γ-substituted Co(III) acetylacetonate complexes

Abstract The He(I) photoelectron spectra of the complexes of Co(III) with acetylacetone and several derivatives are reported. The ionization potentials of metal-localized d -electrons and ligand π-orbitals are used to probe the extent of metal-to-ligand π-bonding and possible aromatic character in the chelate ring.

Relative diels-alder reactivity of 3-alkyl-2-(3-butenyl)-1,2-dihydropyridines. : Interplay of electronic and steric factors related to the 3-alkyl group.

Abstract Steric effects have been found to predominate over Frontier Molecular Orbital (FMO) effects in controlling the relative rates of intramolecular cycloadditions of 3-R-substituted- 2-(3-butenyl)1,2-dihydropyridines (DHP) in the series 4a–c (R = H, Me, Et).

Enantiospecific cleavage of DNA using copper(II) chelated to the periphery of a ligand on a chiral tris-chelate of ruthenium(II)

The A isomer of [Ru(bpy)2ppz2+], but not the Δ, promotes cleavage of plasmid DNA in the presence of copper(II), 3-mercaptopropionic acid and hydrogen peroxide.

Unexpected rate retardation by 4-alkyl substituents in neutral electron demand diels-alder reactions of 2-(3-butenyl)-1,2-dihydropyridines

Abstract Sustmanns equation gives insight into the slower intramolecular reactivity of 4-alkyl-2-(3-butenyl)-1, 2-dihydropyrldines 2a – 2f relative to the parent 1a . Steric effects are inconsistent with the observed rate data.