Receptor-Mediated and Hydrolytic Denitrosylation of Dinitrosyl Iron Complexes to Yield Amorphous Fe_<i>x</i>O_<i>y</i> and Its Photoinduced Transformation into Crystalline Fe@Fe_<i>x</i>O_<i>y</i> Nanoparticles

In this study, denitrosylation of amine-bound {Fe(NO)₂}¹⁰ [(2-A)Fe(NO)₂] (<b>amp-DNIC</b>) was explored to occur through (a) receptor-mediated transfer of ·NO/[NO]^- to [Mn(TPP)(Cl)] and (b) a hydrolytic process leading to the liberation of ·NO together with N₂O. In the presence of the bifunctional ·NO/[NO]^--receptor [Mn(TPP)(Cl)] (TPP = 5,10,15,20-tetraphenyl-21<i>H</i>,23<i>H</i>-porphine), <b>amp-DNIC</b> acts as a dual ·NO/[NO]^- delivery reagent for the conversion of [Mn(TPP)(Cl)] into [Mn(TPP)(NO)] and [Mn(TPP)(NO)₂]. Alternatively, incubation of <b>amp-DNIC</b> in an acetonitrile solution containing 5% deaerated water resulted in its hydrolytic transformation into amorphous Fe_<i>x</i>O_<i>y</i> particles (<b>amp-1</b>) accompanied by the release of ·NO (∼75%), N₂O (∼10%), and nitrite (∼6%). Upon irradiation of <b>amp-DNIC</b> in the presence of the photosensitizer Eosin Y and the sacrificial reductant TEA, the formation of cubic and crystalline Fe@Fe_<i>x</i>O_<i>y</i> core-shell composite carbonaceous material (<b>amp-2</b>) was characterized by high-resolution X-ray diffraction (HRXRD), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), and extended X-ray absorption fine structure (EXAFS). Based on the mechanisms described above, the hydrolytic transformation of <b>amp-DNIC</b> into <b>amp-1</b> occurred, followed by the photoinduced structural rearrangement of <b>amp-1</b>, amorphous Fe_<i>x</i>O_<i>y</i> particles, into <b>amp-2</b>, the cubic and crystalline Fe@Fe_<i>x</i>O_<i>y</i> core-shell composite carbonaceous material.