Synthesis and characterization of molybdenum oxo complexes of two tripodal ligands: reactivity studies of a functional model for molybdenum oxotransferases

Oxygen atom transfer between DMSO and benzoin catalyzed by cis-dioxidomolybdenum(vi) complexes of tetradentate Mannich bases

Dioxidomolybdenum(vi) complexes of tetradentate ONNO donor Mannich base ligands for the catalytic oxygen atom transfer between benzoin and DMSO are reported.

Hydrogen photogeneration catalyzed by a cobalt complex of a pentadentate aminopyridine-based ligand

The combination of a new cobalt complex with a cyclometalated iridium photosensitizer gives an efficient system for H₂ evolution.

Addition of dioxygen to an N4S(thiolate) iron(II) cysteine dioxygenase model gives a structurally characterized sulfinato-iron(II) complex

The non-heme iron enzyme cysteine dioxygenase (CDO) catalyzes the S-oxygenation of cysteine by O(2) to give cysteine sulfinic acid. The synthesis of a new structural and functional model of the cysteine-bound CDO active site, [Fe(II)(N3PyS)(CH(3)CN)]BF(4) (1) is reported. This complex was prepared with a new facially chelating 4N/1S(thiolate) pentadentate ligand. The reaction of 1 with O(2) resulted in oxygenation of the thiolate donor to afford the doubly oxygenated sulfinate product [Fe(II)(N3PySO(2))(NCS)] (2), which was crystallographically characterized. The thiolate donor provided by the new N3PyS ligand has a dramatic influence on the redox potential and O(2) reactivity of this Fe(II) model complex.

Bis- and tris(pyridyl)amine-oxidovanadium complexes: characteristics and insulin-mimetic potential

Two novel vanadium complexes, [V(IV)O(bp-O)(HSO4)] (1) and [V(IV)O(bp-OH)Cl2] x CH3OH (2 x CH3OH), where bp-OH is 2-{[bis(pyrid-2-yl)methyl]amine}methylphenol, were prepared and structurally characterised. EPR spectra of methanol solutions of 2 suggest exchange of Cl- for CH3OH and partial conversion to [VO(bp-OH)(CH3OH)3]2+. Speciation studies on the VO2+-bpOH system in a water/dmso mixture (4:1 v/v) revealed [VO(bp-O)(H2O)n]+ as the dominating species in the pH range 2-7. The insulin-mimetic properties of 1 and 2, [V(IV)O(SO4)tpa] (3), [V(IV)O(pic-trpMe)2] (5) and the new mixed-ligand complexes [V(V)O(pic-trpH)tpa]Cl2 (4Cl2) and [V(V)O(pic-OEt)tpa]Cl2 (6Cl2), tpa = tris(pyrid-2-yl)methylamine, picH-trpH = 2-carboxypyridine-5-(L-tryptophan)carboxamide (picH-trpMe is the respective tryptophanmethyl ester), pic-OEt = 5-carboethoxypyridine-2-carboxylic acid, were evaluated with rat adipocytes, employing two lipolysis assays (release of glycerol and free fatty acids (FFA)), respectively and a lipogenesis assay (incorporation of glucose into lipids). The IC50 values for the inhibition of lipolysis in the FFA assay vary between 0.41 (+/-0.03) (5) and 21.2 (+/-0.6) mM (2), as compared to 0.81 (+/-0.2) mM for VOSO4.