24803-99-4Relevant academic research and scientific papers
Metalloporphyrins as ligands: Synthesis and characterization of [(η6- cymene)-Ru{η5-Ni(OEP)}]2+
Dailey,Yap,Rheingold,Rauchfuss
, p. 1833 - 1835 (1996)
A new bonding mode is present in the lille compound, in which a metalloporphyrin serves as a π ligand. The results of an X-ray crystal structure analysis (shown on the right) and spectroscopic studies clearly show that the metalloporphyrin is strongly affected by the complexation.
Transformations of meso-Iminofunctionalized Pd(II) and Ni(II)-Complexes of β-Alkylsubstituted Porphyrins
Erzina, Dina R.,Zamilatskov, Ilya A.,Stanetskaya, Nadezhda M.,Tyurin, Vladimir S.,Kozhemyakin, Grigory L.,Ponomarev, Gelii V.,Chernyshev, Vladimir V.,Fitch, Andrew N.
, p. 1508 - 1522 (2019)
The meso-imino derivatives of the palladium (II) and nickel (II) complexes of coproporphyrins I and II and β-octaethylporphyrin were obtained by the Vilsmeier formylation followed by interaction with amines. The metal complexes of the azomethines obtained were transformed to the corresponding complexes of cyclopentane and cyclopentane-pyrrolidone fused porphyrin derivatives by thermolysis. The plausible mechanism of such transformations was suggested and substantiated with quantum chemical calculations. Meso-cyano-, meso-hydroxy-, and meso-aminocarbonyl derivatives of β-octaethylporphyrin were obtained by treatment of the corresponding meso-imino derivatives with bases. Demetalation of the nickel complex of the meso- hydroxy-β-octaethylporphyrin led to formation of the free base derivative. The structures of new types of the porphyrin derivatives were determined via X-ray powder diffraction analysis. The obtained types of porphyrins are promising candidates to use as photosensitizers in medicine applications due to their longer wave absorption combined with high stability.
The exhaustive reduction of formylporphyrins to methylporphyrins using dimethylformamide/water as reductant under microwave irradiation
Fletcher, Sarah J.,Harper, Shannon R.,Arnold, Dennis P.
, p. 200 - 208 (2014/05/20)
The reduction of meso-formyl derivatives of 5,15-diaryl- and 5,10,15-triphenylporphyrin (and their nickel(II) complexes) to the corresponding meso-methyl porphyrins is achieved in high yield by microwave heating of the substrate in dimethylformamide (DMF)
Synthesis and Properties of Tris(octaethylporphyrin)s Connected with Vinylene Groups
Higuchi, Hiroyuki,Shimizu, Kenji,Takeuchi, Makoto,Ojima, Juro,Sugiura, Ken-ichi,Sakata, Yoshiteru
, p. 1923 - 1934 (2007/10/03)
Tris(octaethylporphyrin)s, in which two octaethylporphyrin (OEP) rings are connected with vinylene groups at α,γ- and α,β-meso positions of the central OEP ring, were synthesized.The tris(OEP)s have similar conformational and configurational structures to
Does one-electron transfer to nickel(II) porphyrins involve the metal or the porphyrin ligand?
Lexa, Doris,Momenteau, Michel,Mispelter, Jo?l,Savéant, Jean-Michel
, p. 30 - 35 (2008/10/08)
Nickel( I ) complexes can be reversibly produced by one-electron electrochemical reduction of nickel(II) porphyrins within the time scale of cyclic voltammetry as well as thin-layer and conventional cell electrolysis in solvents such as dimethylformamide and benzonitrile. UV-vis and ESR spectroscopies indicate the formation of a nickel(I) complex rather than the anion radical of the nickel(II) porphyrin. ESR data suggest an out-of-plane displacement of the nickel(I) ion caused by the insufficient size of the hole offered by the porphyrin ligand.
The Reductive Chemistry of Nickel Hydroporphyrins. Evidence for a Biologically Significant Difference between Porphyrins, Hydroporphyrins, and Other Tetrapyrroles
Stolzenberg, Alan M.,Stershic, Matthew T.
, p. 6391 - 6402 (2007/10/02)
The chemical and electrochemical reductions of nickel porphyrin and hydroporphyrin complexes in the octaethyl, tetraphenyl, and methylated octaethyl series were investigated in nonaqueous media.The potentials for reduction of the complexes were determined by cyclic voltammetry in three solvents.A single, reversible, one-electron reduction was observed near -1.5 V versus SCE for most complexes in acetonitrile and dimethylformamide.Ni(OEiBC) and Ni(DMOEiBC) had voltammograms with shapes characteristic of electrocatalytic processes when reduced in methylene chloride.Other complexes were generally reduced irreversibly (ip,ap,c) in this solvent.UV-vis, EPR, and 1H NMR spectroscopy were used to characterize the reduced species obtained by electrochemical and chemical means.The site of reduction depends upon the method of reduction (and the time scale of the method), the saturation level of the macrocycle, and the identity of the substituents on the macrocycle.Ni(OEP) is reduced to the anion radical Ni(OEP).-, which undergoes further reduction to afford the stable, diamagnetic phlorin anion complex Ni(OEPH)-.Ni(OEC) and Ni(DMOEiBC) are reduced to transient nickel(I) complexes.NiI(OEC)- reacts further to give the chlorin-phlorin anion complex Ni(OECH)-.Ni(OEiBC) is reduced to NiI(OEiBC)-.Aside from reduced F430, NiI(OEiBC)- is the first stable nickel(I) tetrapyrrole and is the only known nickel(I) complex that has a ?-system extending over the entire macrocycle.Chemical reductions of Ni(TPP), Ni(TPC), and Ni(TPiBC) produce mixtures of anion radical, phlorin anion, and phlorin dianion species.The macrocycles that appear best able to accomodate the large, approximately 2.1 Angstroem Ni-N distance required by nickel(I) are those that were shown to ruffle in neutral, low-spin nickel(II) complexes.One consequence of ruffling is a reduction in the macrocycle core size to give smaller Ni-N distances (1.92 Angstroem) than typically observed in a porphyrin environment.Apparently, the hole size/ligand field strength of hydroporphyrins can be varied over a wide range at little cost in energy.Further consideration of the conformational energy of these complexes suggests that a fundamental difference between porphyrins, hydroporphyrins, corrins, oxoporphyrins, and other tetrapyrrole macrocycles is their optimal hole size and the range of hole sizes that are readily accessible in their complexes.The effects of the stereochemistry of the macrocycle substituents are discussed, and an explanation is developed for the widely varying affinities of nickel tetrapyrroles for axial ligands.
Oxidative chemistry of nickel hydroporphyrins
Stolzenberg, Alan M.,Stershic, Matthew T.
, p. 1614 - 1620 (2008/10/08)
The chemical and electrochemical oxidations of nickel porphyrin, chlorin, and isobacteriochlorin complexes in the octaethyl and methyl-substituted octaethyl series were investigated in nonaqueous media. The potentials for oxidation of the complexes were determined by cyclic voltammetry in acetonitrile, methylene chloride, and dimethylformamide solutions containing TBAP as supporting electrolyte. EPR and absorption spectroscopy were used to characterize the one- and two-electron-oxidized complexes. The first oxidation of all complexes yielded nickel(II) cation radicals. Unlike Ni(TPP).+, the cation radical complexes did not undergo internal electron transfer to afford nickel(III) complexes at low temperatures. Nickel(II) dication complexes were the product of the second oxidation of nickel porphyrins and chlorins in acetonitrile. The second oxidation of nickel isobacteriochlorins afforded nickel(III) cation radical complexes. The results suggest that the greatly enhanced stability of oxidized cis-Ni(OEC) species is not a consequence of redox activity of the coordinated nickel but rather of the ruffled conformation of the macrocycle.
The lowest excited states of copper porphyrins
Asano, Motoko,Kaizu, Youkoh,Kobayashi, Hiroshi
, p. 6567 - 6576 (2007/10/02)
Relaxation processes of excited copper porphyrins were studied with relevance to the structure of the substates of the lowest excited states.Lifetimes of luminescence at room temperature were determined as 17, 29, 69, and 105 ns for T(EtO)PPCu , TPPCu(TPP: 5,10,15,20-tetraphenylporphin), TFPPCu, and OEPCu(OEP: 2, 3, 7, 8,12,13,17,18 octaethylporphin ) in toluene, respectively.Emission intensities and lifetimes of OEPCu and TFPPCu measured as a function of temperature show a variation ascribed to a Boltzmann distribution between the lowest trip-doublet and -quartet with an energy gap of 300-00 cm -1 The anomalous temperature dependence for TPPCu and T( EtO) PPCu is explained by a larger energy gap and larger vibronic distortions in the excited state.The difference in behavior is attributed to the orbital nature of the triplet: a 1 e)>> for OEPCu and TFPPCu but a 2 e)>> for TPPCu and T(EtO)PPCu.The assumption of a low energy charge tl'ansfer state is not necessary for our analysis.
STRUCTURE OF OCTAETHYLPORPHYRIN N-OXIDE AND THE CHARACTERIZATION OF ITS NICKEL(II) AND COPPER(II) COMPLEXES
Balch, Alan L.,Chan, Yee Wai,Olmstead, Marilyn,Renner, Mark W.
, p. 2393 - 2398 (2007/10/02)
The structure of octaethylporphyrin N-oxide has been determined by X-ray crystallography.It crystallizes in the triclic space group P1 (No. 2) with one molecule per unit cell of dimensions a= 7.612 (3) Angstroem, b= 9.740 (4) Angstroem, c=10.566 (4) Angst
Metalloporphyrin Gas and Condenced-Phase Resonance Raman Studies: The Role of Vibrational Anharmonicities as Determinants of Raman Frequencies
Asher, Sanford A.,Murtaugh, James
, p. 7244 - 7251 (2007/10/02)
The first resonance Raman spectra of gas-phase porphyrins are reported.An extensive temperature-dependent study of the Raman spectra of nickel(II) and cobalt(II) octaethylporphyrine both in the gas phase and in condenced solution phases demonstrates a large temperature dependence of the Raman frequencies.The small frequency differences observed between the gas- and condenced phase samples indicate that the van der Waals interactions occuring in hydrocarbon solvents do not affect the heme frequencies.The temperature dependence of Raman frequencies shows an apparent activation energy.This temperature dependence is interpreted as arising from anharmonic interactions between high-frequency vibrations and thermally populated low-frequency vibrations.Frequency shifts as large as 15 cm-1 are observed between 40 and 600 K for the heme core size dependent Raman vibrations.These shifts may be interpreted as an expansion of the heme ring as low-frequency vibrations are thermally populated.The large temperature dependence of the heme vibrational frequencies may account for some of the spectral shifts observed in photochemically generated transient Raman studies in heme proteins.Transient heme temperature increases of greater than 100 K are expected to occur during photolysis of liganded heme complexes such as carbon monoxyhemoglobin and carbon monoxymyoglobin.This temperature increase will result in shifts to lower frequency for the heme Raman vibrations.
