The precise analysis of redox chemistry of MN4-based macrocyclic complexes is of great importance because of stabilization of unusual oxidation states of metal ions by macrocyclic ligand and thus have various applications in biochemistry, electrochemistry, electrocatalysis, pharmaceuticals etc. In this work, MN4-macrocyclic complexes of Co (II) and Ni(II) transition metal ...

Photoautotrophic bacteria that oxidize ferrous iron (Fe[II]) under anaerobic conditions are thought to be ancient in origin, and the ferric (hydr)oxide mineral products of their metabolism are likely to be preserved in ancient rocks. Here, two enrichment cultures of Fe(II)-oxidizing photoautotrophs and a culture of the genus Thiodictyon were studied with respect to their ability to fractionate ...

We present near-infrared (observed frame) spectra of the high-redshift quasar S4 0636+68 at z = 3.2 which was previously thought to be one of a group of “strong” Fe II emitters (i.e., F (Fe IIλλ4434–4684)/F (Hβ) > 1). Our K-band spectrum clearly shows emission lines of Hβ and [O III]λλ4959, 5007 as well as optical Fe II emission. Our computed value of F (Fe II λλ4434–4684)/F (Hβ) ≃ 0.8 for S4 0...

The potential for microbially catalyzed NO3(-)-dependent oxidation of solid-phase Fe(II) compounds was examined using a previously described autotrophic, denitrifying, Fe(II)-oxidizing enrichment culture. The following solid-phase Fe(II)-bearing minerals were considered: microbially reduced synthetic goethite, two different end products of microbially hydrous ferric oxide (HFO) reduction (bioge...

A method for speciation and determination of low levels of dissolved iron in rainwater was established by coupling reverse flow injection analysis with a 2-m liquid waveguide capillary cell and spectrophotometric detection. Ferrozine solution was injected into a sample stream to form an Fe(II)-ferrozine complex with Fe(II), and the absorbance of this complex was detected at both 562 nm and 625 ...

The important question of iron bioavailability in the sea has become complicated by the discovery that marine phytoplankton can take up Fe bound in very stable chelates via reductive processes, and some particular Fe species through specialized transport mechanisms. As a result there is some question of whether the small fraction of Fe that is ‘‘free’’ or unchelated in seawater is important in ...

We obtained 0.8-2.4 µm spectra at a resolution of 320 km s −1 of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on the analysis of the Fe II emission in that region and the kinematics of the low-ionization broad lines. We show that the 1µm Fe II lines (λ9997, λ10501, λ10863 and λ11126) are the strongest Fe II lines in the observed i...

Proton NMR studies at 360 MHz establish the binary Fe(II)-bleomycin complex to be paramagnetic with a spectrum covering 70 ppm. Addition of carbon monoxide generates a stable, diamagnetic Fe(II)-bleomycin-CO complex that is a putative structural analog of the "active" Fe(II)-bleomycin-O2 complex. The following six groups have been determined to be coordinated to the Fe(II) ion from analysis of ...

Schiff base macrocycles are emerging as useful scaffolds for binding two or more catalytic metals in close proximity. Such coordination chemistry allows for the evaluation of potentially beneficial catalytic cooperative effects. In the field of ring opening polymerization (ROP) of cyclic esters, only a handful of metal systems bound by Schiff base [2 + 2] type macrocycles have been studied. Nev...