Kinetics, mechanism, and spectroscopy of the reversible binding of nitric oxide to aquated iron(II). An undergraduate text book reaction revisited

A detailed kinetic and mechanistic analysis of the classical "brown-ring" reaction of [Fe(H2O)(6)](2+) with NO was performed using stopped-flow and laser flash photolysis techniques at ambient and high pressure. The kinetic parameters for the "on" and "off" reactions at 25 degreesC were found to be k(on) = 1.42 x 10(6) M-1 s(-1), DeltaH(on)(double dagger) = 37.1 +/- 0.5 kJ mol (-1), DeltaS(on)(double dagger) = -3 +/- 2 J K-1 mol(-1), DeltaV(on)(double dagger) = + 6.1 +/- 0.4 cm(3) mol(- 1), and k(off) = 3240 +/- 750 s(-1), Delta(off)(double dagger) = 48.4 +/- 1.4 kJ mol(-1), DeltaS(off)(double dagger) = -15 +/- 5 J K-1 mol-1, DeltaV(off)(double dagger) = +1.3 +/- 0.2 cm(3) mol(-1). These parameters suggest that both reactions follow an interchange dissociative (I-d) ligand substitution mechanism, which correlates well with the suggested mechanism for the water exchange reaction on [Fe(H2O)(6)](2+). In addition, Mossbauer spectroscopy and EPR measurements were performed on the reaction product [Fe(H2O)(5)(NO)](2+). The Mossbauer and EPR parameters closely resemble those of the {FeNO}(7) units in any of the other well-characterized nitrosyl complexes. It is concluded that its electronic structure is best described by the presence of high-spin Fe-III antiferromagnetically coupled to NO- (S = 1) yielding the observed spin quartet ground state (S= 3/2), i.e., [Fe-III(H2O)(5)(NO-)](2+), and not [Fe- I(H(2)0)(5)(N0(-))](2+) as usually quoted in undergraduate text books

Indocyanine green as a prospective sensitizer for photodynamic therapy of melanomas

Spectroscopic, photochemical and biological properties of indocyanine green (ICG) are presented. Light over 800 nm is effectively absorbed by ICG. This property as well as photochemical behaviour of ICG make it a very suitable dye for photodynamic treatment of melanoma cells. Cytotoxicity of ICG itself and the effect of photodynamic therapy (PDT) were evaluated by following the growth of human (SKMEL 188) and mouse (S91) melanoma cells. The surviving fraction of the cells irradiated (lambda(ex) = 830 nm) vs non-irradiated, treated with the same dose of ICG, is significantly decreased (5- to 10-fold). These results show that ICG is a very promising dye for photodynamic therapy of melanomas

Anticancer activity of ruthenium(II) polypyridine complexes bearing pyrrolidine substituents

International audienceA set of homoleptic ruthenium polypyridine (bipyridine and terpyridine) complexes flanked with several electron-donating pyrrolidine moieties has been characterized and the anticancer activity was evaluated toward human lung adenocarcinoma epithelial (A549) and murine colon carcinoma (CT26). Good antiproliferative effects were observed with an IC50 ranging from ca. 4 to 21 mu M against both cell lines. Dependence was found between the cytotoxicity, the lipophilicity and the Ru-II/Ru-III oxidation potential. All the studied compounds interacted quite well with albumin while the interaction with DNA was marginal. The biological studies revealed that the ruthenium complexes induced the ROS overproduction which might be one but not the only way of cell death induction