Colloidal ferrite spinel nanoparticles (Co x Ni 1-x Fe 2 O 4 ) were prepared by a microwave-stimulated Bradley technique under nonhydrolytic conditions. The effect of Ni 2+ doping on the structural properties was studied by powder XRD. The particle size, hydrodynamic size, and morphology were evaluated by transmission electron microscopy (TEM) and dynamic light scattering (DLS), which showed mean crystallite sizes of ca. 10 and 60 nm for powder and colloidal suspensions of Co x Ni 1-x Fe 2 O 4 , respectively. The cytotoxicity of the nanoparticles was tested against murine macrophages J774.E, osteosarcoma D17 cells, and human red blood cells (RBCs). The adsorption of bovine serum albumin (BSA) was studied, and the BSA showed a high affinity for the surface [a]
A new base metal iron‐cobalt dyad has been obtained by connection between a heteroleptic tetra‐NHC iron(II) photosensitizer combining a 2,6‐bis[3‐(2,6‐diisopropylphenyl)imidazol‐2‐ylidene]pyridine with 2,6‐bis(3‐methyl‐imidazol‐2‐ylidene)‐4,4′‐bipyridine ligand, and a cobaloxime catalyst. This novel iron(II)‐cobalt(III) assembly has been extensively characterized by ground‐ and excited‐state methods like X‐ray crystallography, X‐ray absorption spectroscopy, (spectro‐)electrochemistry, and steady‐state and time‐resolved optical absorption spectroscopy, with a particular focus on the stability of the molecular assembly in solution and determination of the excited‐state landscape. NMR and UV/Vis spectroscopy reveal dissociation of the dyad in acetonitrile at concentrations below 1 mM and high photostability. Transient absorption spectroscopy after excitation into the metal‐to‐ligand charge transfer absorption band suggests a relaxation cascade originating from hot singlet and triplet MLCT states, leading to the population of the 3MLCT state that exhibits the longest lifetime. Finally, decay into the ground state involves a 3MC state. Attachment of cobaloxime to the iron photosensitizer increases the 3MLCT lifetime at the iron centre. Together with the directing effect of the linker, this potentially makes the dyad more active in photocatalytic proton reduction experiments than the analogous two‐component system, consisting of the iron photosensitizer and Co(dmgH)2(py)Cl. This work thus sheds new light on the functionality of base metal dyads, which are important for more efficient and sustainable future proton reduction systems.
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