Binding of an Oxo-Bridged Dinuclear Iron(III) Complex{[Fe(phen)(H2O)3]2O}(SO4)2 to DNA and Its Recognition of Single- and Double-Stranded DNA As Determined by Electrochemical Studies

An earth-abundant system for light-driven CO2 reduction to CO using a pyridinophane iron catalyst

Herein we report an earth-abundant photocatalytic system for CO2 reduction to CO based on an iron catalyst combined with a CuI photosensitizer. Under visible light irradiation CO is produced as the main product (TONCO = 565, TOFmaxCO = 114 h-1) with a high selectivity over H2 production (SelCO2 = 84%).

Application of a europium complex, Eu(AA)3phen (AA=acrylic acid, phen=1,10-phenanthroline) as a spectroscopic probe and cleaving reagent of DNA

A complex Eu(AA)3phen was synthesized and characterized by elemental analysis, IR spectroscopy and (1)H NMR. Interaction between Eu(AA)3phen and DNA was studied by UV/visible absorption spectroscopy, fluorescence spectrophotometer, circular-dichroism (CD) spectra and gel-electrophoresis measurements. Absorption spectral indicated that Eu(AA)3phen binding to DNA was an electrostatic mode, which was authenticated by the effect of ionic strength, thermal denaturation and fluorescence quenching experiments. The intrinsic binding constant Kb of Eu(AA)3phen was calculated to be 1.6×10(4) L mol(-1).

Synthesis, structure, and solution properties of [(mim-TASN)FeCl2]+ and its μ-oxo derivative

A series of iron(III) complexes based on the tetradentate ligand 4-((1-methyl-1H-imidazol-2-yl)methyl)-1-thia-4,7-diazacyclononane (L) has been synthesized, and their solution properties investigated. Addition of FeCl(3) to methanol solutions of L yields [LFeCl(2)]FeCl(4) as a dark red solid. X-ray crystallographic analysis reveals a pseudo-octahedral environment around iron(III) with the three nitrogen donors of L coordinated facially. Ion exchange reactions with NaPF(6) in methanol facilitate chloride exchange resulting in a different diastereomer for the [LFeCl(2)](+) cation. X-ray analysis of [LFeCl(2)]PF(6) finds meridional coordination of the three nitrogen donors of L. Electrochemical studies of [LFeCl(2)](+) in acetonitrile display a single Fe(III)/(II) reduction potential at -280 mV versus ferrocenium/ferrocene. In methanol, a broad cathodic wave is observed because of partial exchange of one chloride for methoxide with half-potentials of -170 mV and -440 mV for [LFeCl(2)](+/0) and [LFeCl(OCH(3))](+/0), respectively. The equilibrium constants for chloride exchange are 7 × 10(-4) M(-1) for Fe(III) and 2 × 10(-8) M(-1) for Fe(II). In aqueous solutions chloride exchange yields three accessible complexes as a function of pH. Strongly acidic conditions yield the aqua complex [LFeCl(OH(2))](2+) with a measured pK(a) of 3.8 ± 0.1. Under mildly acidic conditions, the μ-OH complex [(LFeCl)(2)(OH)](3+) with a pK(a) of 6.1 ± 0.3 is obtained. The μ-oxo complex [(LFeCl)(2)(O)](2+) is favored under basic conditions. The diiron Fe(III)/Fe(III) complexes [(LFeCl)(2)(OH)](3+) and [(LFeCl)(2)(O)](2+) can be reduced by one electron to the mixed valence Fe(III)/Fe(II) derivatives at -170 mV and -390 mV, respectively. From pH dependent voltammetric studies, the pK(a) of the mixed valent μ-OH complex [(LFeCl)(2)(OH)](2+) is calculated at 10.3.

Discrete tetrairon(III) cluster exhibiting a square-planar Fe4(mu4-O) core: structural and magnetic properties

The aerobic reaction of the Schiff-base ligand N-(benzimidazol-2-yl)salicylaldimine (Hbisi) with iron(II) perchlorate in methanol leads to the formation of the remarkable coordination compound [Fe(4)(mu(4)-O)(mu-MeO)(4)(bisi)(4)](ClO(4))(2) x 4 MeOH (1), whose single-crystal X-ray structure reveals the presence of a discrete Fe(III)(4)(mu(4)-O) core. Magnetic and Mossbauer studies both show that the exchange interaction within the square tetranuclear iron(III) unit is dominated by the central bridging mu(4)-oxido ligand, the involvement of the mu-methoxido bridges being negligible.