75557-96-9

Upstream product

• 616-47-7 1-methyl-1H-imidazole 
• 105118-92-1 chloroiron(III) meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinate 
• 52629-13-7 [(all-cis)-5,10,15,20-tetrakis-[2-(2,2-dimethylpropionamido)phenyl]porphyrinato^(2-)]-iron(II) 

Downstream Products

• 75559-87-4 (O2)iron(1-methylimidazole)(α,α,α,α-5,10,15,20-tetrakis[o-pivalamidophenyl]porphyrinate) 
• 55449-22-4 (5,10,15,20-tetrakis(α,α,α,α-O-pivalamidophenyl)porphyrinato)iron(II)(1-methylimidazole)(O2) 
• 105118-92-1 chloroiron(III) meso-α,α,α,α-tetrakis(o-pivalamidophenyl)porphyrinate 

Relevant academic research and scientific papers

Spectroscopic investigations into the binding of hydrogen sulfide to synthetic picket-fence porphyrins

The reversible binding of hydrogen sulfide (H2S) to hemeprotein sites has been attributed to several factors, likely working in concert, including the protected binding pocket environment, proximal hydrogen bond interactions, and iron ligation environment. To investigate the importance of a sterically-constrained, protected environment on sulfide reactivity with heme centers, we report here the reactivity of H2S and HS- with the picket-fence porphyrin system. Our results indicate that the picket-fence porphyrin does not bind H2S in the ferric or ferrous state. By contrast, reaction of the ferric scaffold with HS- results in reduction to the ferrous species, followed by ligation of one equivalent of HS-, as evidenced by UV-vis, NMR spectroscopy and mass spectrometry studies. Measurement of the HS- binding affinities in the picket-fence or tetraphenyl porphyrin systems revealed identical binding. Taken together, these results suggest that the protected, sterically-constrained binding pocket alone is not the primary contributor for stabilization of ferric H2S/HS- species in model systems, but that other interactions, such as hydrogen bonding, must play a critical role in facilitation of reversible interactions in ferric hemes.

Kinetics and Mechanism of Reductive Dioxygen Activation Catalyzed by the P-450 Model System. Iron Picket Fence as a Catalytic Center

Picket-fence porphyrin (TpivPP)-iron-N-methylimidazole-O2 complex is used as an artifical P-450, and the decomposition rates are investigated in detail in the presence of HCl and H2-colloidal platinum supported on poly(vinylpyrrolidone) with or without addition of benzoic anhydride.From the decay rates of the oxy complex followed by electronic spectrum under a variety of conditions, pseudo-first-order rate (with the complex) constants are obtained.The pseudo-first-order constants are proportional to first order with the colloidal platinum and first order with dihydrogen.Analysis of the dependence of the rate constants on the acidity strongly suggests the simultaneous participation of the protonated and unprotonated oxy complexes in the transition states.Cyclohexene used as a guest does not affect the rate at all, demonstrating that the product-forming step comes later than the rate-determining step.It is also ascertained that H2 favorably competes with cyclohexene in the product-forming step under the conditions of the rate measurements.However, competitive oxidation of the present artifical P-450 porphirin is satisfactorily slow, and solvent oxidation is not appreciable.Products of the present acid-catalyzed reductive decomposition of the oxy complex are corresponding ferric (deoxy) complex, trans-cyclohexan-1,2-diol ethyl ether drived from cyclohexene oxide and ethanol.Slow regeneration of the ferrous oxy complex from the ferric complex leads to the effective recycling (turnover) of the artifical P-450 system.

Oxygenation Patterns for Substituted meso-Tetraphenylporphyrin Complexes of Iron(II). Spectroscopic Detection of Dioxygen Complexes in the Absence of Amines

The reaction of dioxygen with iron(II) porphyrins in inert solvents has been studied by 1H NMR spectroscopy in order to detect the presence of reactive intermediates.Sterically hindered porphyrins have been examined in which the formation of peroxo- and oxo-bridged dimeric structure is limited.The iron(II) porphyrins studied have 1H NMR spectra characteristic of intermediate-spin (S = 1), four-coordinate species.Reduction of iron(III) chloride (FeIIICl) or iron(III) chloride (FeIIICl) with either aqueous sodium dithionite or zinc amalgam in dichloromethane solution produces FeII or FeII.The previously reported reduction of these two porphyrins with piperidine has been reexamined and shown to form the bis(pipridine) adducts of the iron(II) porphyrins.Addition of dioxygen to paramagnetic iron(II) (FeII) in toluene solution below -70 deg C produces a new diamagnetic complex that is formulated as FeO2. 1H NMR spectroscopic observations indicated that, on warming, this species is successively converted to FeIIIO2FeIII and to FeIIIOFeIII.The latter has been previously isolated.Reaction of FeO2 with N-methylimidazole (N-MeIm) at -70 deg C results in the formation of (N-MeIm)FeO2.Addition of oxygen to FeII at -70 deg C in toluene solution results in the formation of diamagnetic FeO2.This, on warming, is converted to FeO2Fe and then to FeOH and FeOFe as the final stable products.Addition of dioxygen to FeII and FeII in dichloromethane solution at -70 deg C produces diamagnetic dioxygen adducts.On warming, these undergo dissociation to form the parent iron(II) complex and irreversible oxidation to form iron(III) porphyrin hydroxide and chloride.