17632-19-8Relevant articles and documents
Cis-influence of hydroporphyrin macrocycles on axial ligation equilibria and alkyl exchange reactions of alkylcobalt(III) porphyrin complexes.
Stolzenberg,Summers
, p. 1518 - 1524 (2000)
Stability constants are reported for the coordination of pyridine and substituted pyridines to the alkylcobalt(III) complexes of octaethylporphyrin (OEP), t-octaethylchlorin (OEC), and ttt-octaethylisobacteriochlorin (OEiBC) in toluene solution. The stability constants correlate with the base strength of the nitrogenous ligand. A cis-influence of the macrocycle saturation level on the stability constants is observed. Stability constants for coordination of a given pyridine ligand to an alkylcobalt(III) complex are roughly 10 times smaller than the stability constants for the corresponding cobalt(II) complex. Analysis of a thermodynamic cycle demonstrates that this leads to decreased stability of the complex with respect to Co-C bond homolysis upon ligand coordination, a base-on effect. Alkyl exchange occurs between cobalt complexes of different tetrapyrroles. Equilibrium data establish that the exchange is nonstatistical and that the Co-C bond is stabilized by increasing the saturation of the tetrapyrrole macrocycle.
Synthesis and Spectral Properties of meso-Nitro-Substituted Octaethylporphyrins and Their Co(II) Complexes
Chizhova, N. V.,Mamardashvili, N. Zh.,Rusanov, A. I.
, p. 1878 - 1883 (2020)
Abstract: The reaction of 2,3,7,8,12,13,17,18-octaethylporphyrin with sodium nitrite in trifluoroacetic acid produced 5-nitro-2,3,7,8,12,13,17,18-octaethylporphyrin, 5,15-dinitro-2,3,7,8,12,13,17,18-octaethylporphyrin, and 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin. Reactions of octaethylporphyrin, mono-, di-, tri-, and tetranitro-substituted porphyrins coordination to cobalt(II) acetate in a chloroform–methanol mixture were studied. The corresponding Co(II) porphyrinates were obtained and identified. It was shown that, upon dissolution of Co(II) octaethylporphyrinates in dimethylformamide in the presence of NaOH, the Co(II)→Co(III) oxidation occurs in the coordination site of the macrocycle.
Generation of an (alkoxycarbonyl)rhodium complex in an alcohol analog of the water-gas shift reaction
Miller, Roy G.,Kyle, Jeffrey A.,Coates, Geoffrey W.,Anderson, D. Joe,Fanwick, Phillip E.
, p. 1161 - 1166 (1993)
(Octaethylporphyrinato)rhodium(II) dimer ((OEPRh)2, 1) reacts with CO and ethanol in CH2Cl2 to give (octaethylporphyrinato)rhodium(III) chloride (5), (ethoxycarbonyl)(octaethylporphyrinato)rhodium(III) (OEPRh(CO)OEt, 6), and formyl(octaethylporphyrinato)rhodium(III) (2). The structure of 6 was clarified by X-ray diffraction analysis. Complex 6 crystallized in the monoclinic space group P21/n (No. 14) with a = 14.581 (1) ?, b = 14.181 (2) ?, c = 17.4530 (9) ?, V = 3608.8 (9) ?3, Z = 4, R = 0.046, Rw = 0.051, and T = 293 K for 415 parameters and 4864 reflections. The 1H and 13C spectral properties of 2 and 6 in CD2Cl2 were determined and the behaviors of 1, 2, (octaethylporphyrinato)rhodium(III) hydride (3), and 6 in CH2Cl2 solvent were examined. Photolysis of 2 in CH2Cl2 at 300 nm afforded (octaethylporphyrinato)rhodium(III) chloride. Treatment of OEPCoNa with acetic anhydride in ethylene glycol dimethyl ether afforded acetyl(octaethylporphyrinato)cobalt(III) and an analogous experiment with acetic formic anhydride generated an acyl(octaethylporphyrinato)cobalt(III) complex.
Chelation, formulation, encapsulation, retention, and in vivo biodistribution of hydrophobic nanoparticles labelled with 57Co-porphyrin: Oleylamine ensures stable chelation of cobalt in nanoparticles that accumulate in tumors
Hervella, Pablo,Dam, Johan Hygum,Thisgaard, Helge,Baun, Christina,Olsen, Birgitte Brinkmann,H?ilund-Carlsen, Poul Flemming,Needham, David
, p. 11 - 25 (2018)
Background and motivation: While small molecules can be used in cancer diagnosis there is a need for imageable diagnostic NanoParticles (NPs) that act as surrogates for the therapeutic NPs. Many NPs are composed of hydrophobic materials so the challenge is to formulate hydrophobic imaging agents. To develop individualized medical treatments based on NP, a first step should be the selection of patients who are likely responders to the treatment as judged by imaging tumor accumulation of NPs. This requires NPs with the same size and structure as the subsequent therapeutic NPs but labelled with a long-lived radionuclide. Cobalt isotopes are good candidates for NP labelling since 55Co has half-life of 17.5 h and positron energy of 570 keV while 57Co (t1/2 271.6 d) is an isotope suited for preclinical single photon emission tomography (SPECT) to visualize biodistribution and pharmacokinetics of NPs. We used the hydrophobic octaethyl porphyrin (OEP) to chelate cobalt and to encapsulate it inside hydrophobic liquid NPs (LNPs). We hypothesized that at least two additional hydrophobic axial ligands (oleylamine, OA) must be provided to the OEP-Co complex in order to encapsulate and retain Co inside LNP. Results: 1. Cobalt chelation by OEP and OA. The association constant of cobalt to OEP was 2.49 × 105 M?1 and the formation of the hexacoordinate complex OEP-Co-4OA was measured by spectroscopy. 2. NP formulation and characterization: LNPs were prepared by the fast ethanol injection method and were composed of a liquid core (triolein) surrounded by a lipid monolayer (DSPC:Cholesterol:DSPE-PEG2000). The size of the LNPs loaded with the cobalt complex was 40 ± 5 nm, 3. Encapsulation of OEP-Co-OA: The loading capacity of OEP-Co-OA in LNP was 5 mol%. 4. Retention of OEP-57Co-4OA complex in the LNPs: the positive effect of the OA ligands was demonstrated on the stability of the OEP-57Co-4OA complex, providing a half-life for retention in PBS of 170 h (7 days) while in the absence of the axial OA ligands was only 22 h. 5 Biodistribution Study: the in vivo biodistribution of LNP was studied in AR42J pancreatic tumor-bearing mice. The estimated half-life of LNPs in blood was about 7.2 h. Remarkably, the accumulation of LNPs in the tumor was as high as 9.4% ID/g 24 h after injection with a doubling time for tumor accumulation of 3.22 h. The most important result was that the nanoparticles could indeed accumulate in the AR42J tumors up to levels greater than those of other NPs previously measured in the same tumor model, and at about half the values reported for the molecular agent 57Co-DOTATATE. Conclusions: The additional hydrophobic chelator OA was indeed needed to obtain a stable octahedral OEP-Co-4OA. Cobalt was actually well-retained inside LNP in the OEP-Co-4OA complex. The method described in the present work for the core-labelling of LNPs with cobalt is now ready for labeling of NPs with 55Co, or indeed other hexadentate radionuclides of interest for preclinical in vivo PET-imaging and radio-therapeutics.
Structure of Phenyl Derivatives of Octaethylporphyrin and Dissociation Kinetics of Their Mn3+, Co2+, and Cu2+ Complexes in Acetic Acid
Kuvshinova,Kuz'min,Pukhovskaya,Semeikin,Golubchikov
, p. 652 - 654 (2007/10/03)
Octaethyl-, 5-phenyloctaethyl-, 5,15-diphenyloctaethyl-, 5,10,15,20-tetraphenyloctaethyl, and dodecaphenylporphyrins were prepared, and their geometries were optimized by the method of molecular mechanics. The deformation of the porphyrin macroring grows
