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Cobalt(III) tetraphenylporphyrin catalyses a hydride transfer reaction from tributyltin hydride to 10-methylacridinium ion via the formation of hydridocobalt(III) tetraphenylporphyrin, which is the rate-determining step, followed by facile hydride transfer from the hydridocobalt(III) porphyrin to 10-methylacridinium ion in acetonitrile. Tributyltin hydride is also effective for the hydrometallation of alkenes and alkynes with cobalt(III) tetraphenylporphyrin to yield the corresponding organocobalt(III) porphyrins regioselectively. The hydrometallation is suggested to proceed via the hydride transfer from tributyltin hydride to cobalt(III) tetraphenylporphyrin to give the hydridocobalt(III) porphyrin, followed by the hydrogen transfer from hydridocobalt(III) porphyrin to alkenes and alkynes to yield the corresponding organocobalt(III) porphyrins. The regioselectivities are consistent with the stabilities of radicals generated by the hydrogen transfer from hydridocobalt(III) porphyrin to alkenes and alkynes. The rates of the electrophilic cleavage of cobalt-carbon bonds of organocobalt(III) porphyrins by trifluoroacetic acid in MeCN are also reported.

A procedure has been devised by which quantitative coordination of Ru(NH₃)₅²⁺ groups to the nitrile sites in [5,10,15,20-tetrakis(4-cyanophenyl)porphyrinato]cobalt(II) and [5,10,15,20-tetrakis(4-cyano-2,6-dimethylphenyl)porphyrinato]cobalt(II) can be achieved. The procedure takes advantage of the solubility of both [Ru(NH₃)₅(OSO₂CF₃)](CF₃SO₃)₂ and either porphyrin in a mixed solvent consisting of 1,2-dimethoxyethane/N,N-dimethylacetamide (27:1 v/v). This new synthetic procedure allowed the fully ruthenated porphyrins to be isolated as solids in milligram quantities. The products were characterized using cyclic and rotating disk voltammetry and infrared and NMR spectroscopy.

Iron porphyrin and cobalt porphyrin were respectively modified on glassy carbon (GC) electrodes together with multiwalled carbon nanotubes (MWCNTs), and the modified electrodes were characterized by X-ray photoelectron spectroscopy (XPS). Their electrochemical performance for the reduction of oxygen (O₂), proton (H⁺) and carbon dioxide (CO₂) were respectively investigated and compared by cyclic voltammetry (CV). The results showed that iron porphyrin-MWCNT modified electrode always had a better performance than cobalt porphyrin-MWCNT modified electrode. It is proposed that iron porphyrin-MWCNT modified electrode will have promising application in electrochemical architectures like microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) for its good biocompatibility, easy availability, as well as excellent electrochemical performance.

Two types of cobalt porphyrins, viz., meso-tetrakis(tolylporphyrinato)cobalt(II), (TTP)Co (1), and meso-tetrakis(triphenylamino porphyrinato)cobalt(II), [(TPA)₄P]Co, (2) were self-assembled via metal-ligand axial coordination of phenyl imidazole functionalized fulleropyrrolidine, ImC${}_{60}$ to form a new series of donor–acceptor constructs. A 1:2 complex formation with ImC${}_{60}$ was established in the case of (TTP)Co while for [(TPA)₄P]Co only a 1:1 complex was possible to positively identify. The binding constants $K_1$ and $K_2$ for step-wise addition of ImC${}_{60}$ to (TTP)Co were found to be 1.07 × 10⁵ and 3.20 × 10⁴ M${}^{-1}$, respectively. For [(TPA)₄P]Co:ImC${}_{60}$, the measured $K_1$ values was found to be 6.48 × 10⁴ M${}^{-1}$, slightly smaller than that observed for (TTP)Co. Although both cobalt porphyrins were non-fluorescent, they were able to quench the fluorescence of ImC${}_{60}$ indicating occurrence of excited state events in the supramolecular donor-acceptor complexes. Electrochemistry coupled with spectroelectrochemistry, revealed the formation of cobalt(III) porphyrin cation instead of a cobalt(II) porphyrin radical cation, as the main product, during oxidation of phenyl imidazole coordinated cobalt porphyrin. With the help of computational and electrochemical results, an energy level diagram was constructed to witness excited state photo-events. Competitive energy and electron transfer from excited CoP to coordinated ImC${}_{60}$, and electron transfer from Im¹C${}_{60}$* to cobalt(II) porphyrin resulting into the formation of PCo${}^{III}$:ImC${}_{60}^{•-}$ charge separated state was possible to envision from the energy diagram. Finally, using femtosecond transient absorption spectroscopy and data analysis by Glotaran, it was possible to establish sequential occurrence of energy transfer and charge separation processes. The lifetime of the final charge separated state was $\sim$ 2 ns. A slightly better charge stabilization was observed in the case of [(TPA)₄P]Co:ImC${}_{60}$ due to the presence of electron rich, peripheral triphenylamine substituents on the cobalt porphyrin.

To prepare the novel plate-like nanocomposite Co^IIITMPyP/Nb₃O₈, the cationic cobalt (III) tetrakis–5, 10, 15, 20–(N–methyl–4–pyridyl) porphyrin (Co^IIITMPyP) was intercalated into the interlayer of the perovskite structural material KNb₃O₈ via the electrostatic self-assembly of the positively charged Co^IIITMPyP molecules and the electronegative Nb₃O${}_8^{-}$ nanosheets. The Nb₃O${}_8^{-}$ nanosheets was obtained by exfoliating the protonated product of niobate KNb₃O₈ in the tetrabutyl ammonium hydroxide (TBA${}^{+}$OH${}^{-}$) aqueous solution. The zeta potential was measured to indicate the stability and uniformity of the Nb₃O${}_8^{-}$ nanosheet colloidal dispersion, and the structure and component of the parent material KNb₃O₈, the acidified product HNb₃O₈, and the interlayered nanocomposite Co^IIITMPyP/Nb₃O₈ were characterized using XRD, FT-IR, SEM and AFM. Furthermore, the electrocatalytic activity toward the oxygen reduction reaction (ORR) of Co^IIITMPyP/Nb₃O₈ hybrids modified GCE was investigated by the cyclic voltammetry (CV) measurements. The modified GCE exhibited good electrocatalytic activity toward ORR in consideration of the peak shift from $-$0.723V to $-$0.300V. The linear correlation of the reduction peak current and the square root of the scan rate suggested a diffusion controlled process.