Journals

Solutions of porphyrin (H₂L) complexes, RuL(MeCN)₂, in MeCONMe₂, DMF, or pyrrole, bind 1.0 mol of O₂ per Ru reversibly at 20 ^oC and 1 atm pressure. The MeCN complexes are prepared by photolysis of the corresponding RuL(CO)(EtOH), complexes in MeCN. In PhMe solution, the O₂ reaction leads only to a slow irreversible oxidation to Ru(III). Related complexes with more strongly coordinated axial ligands, such as pyridine and N-methylimidazole, also give only oxidation products. Electrolysis of the bisacetonitrile complex brings about a reversible 1-electron oxidation to give a Ru(III) cation.

2-Formyl-4-vinyl-deuterohemin- and 2-vinyl-4-formyl-deuterohemin-substituted horseradish peroxidase were prepared from apoperoxidase and the respective hemins. The 2 hemins bind at different rates to the apoprotein and the resultant substituted peroxidases possess different visible spectra and activities. Thus, the hemin 2 and 4 substituents interact with apoperoxidase and are not exposed to the solvent.

The interactions between dimeric porphyrins I (n = O-8), covalently linked at their peripheries, were measured from their electronic absorption spectra and ¹³C NMR spectra. For I (n less than 2), interactions between the 2 rings are observed; for I (n greater than 2), the interactions decrease.

Heating a mixture of RuCl₃H₂O and o-cyanobenzamide in naphthalene to 290 ^oC for 1 h, followed by cooling, addition of EtOH to the residue, filtering the suspension, and drying gave a solid residue which was Soxhlet-extracted with glacial HOAc, dried, and reextracted with pyridine or its derivatives to give RuPcL₂ (I; H₂Pc = phthalocyanine, L = pyridine, 4-methylpyridine, 4-tert-butylpyridine). CO was bubbled through a refluxing solution of RuPcL₂ in diglyme to give RuPcL(CO) (II). Refluxing of Ru₃(CO)₁₂ and PcH₂ in PhCN gave a dark blue solid, probably RuPc(CO), which upon Soxhlet extraction with pyridines gave II also.

While CuII porphyrins are known to luminescence, Ag^II complexes do not. Ag^III octethylporphyrin has no emission while Au^III tetraphenylporphyrin has a moderabely intense phosphorescence with a nonexponential decay fit with 2 decay times of 63 and 184 μs. In contrast to Cu^II porphyrins, the Ag complexes have a metal redox potential, II to III, between that of ring oxidation and ring reduction suggesting that luminescence is quenched by low-energy charge transfer transitions Ag^II → ring or ring → Ag^III. Near-IR (700-1100 nm) absorption spectra confirm the presence of weak absorption bands in Ag^II and Ag^III complexes that are not observed in complexes of Cu^II and Au^III. The near-IR absorption of Cu^II(TPP) and the quenching of its unusually broad emission by pyridine suggest that a charge transfer state is close to the emitting level. Iterative extended Huckel calculations explain these facts by the energy of orbital b_1g(dx²-y²), which rises along the series Cu < Ag < Au.

Analysis of stool specimens from a patient with familial coproporphyria by high-performance liquid chromatography revealed that 112 μg/g of dry feces (14% of the total porphyrin present) was Cu coproporphyrin. Examination of stool specimens from other patients with this disease confirmed the presence of significant amtounts of both Cu coproporphyrin and coproporphyrin. Further investigation showed that the Cu coproporphyrin was probably formed by a nonenzymic incorporation of Cu in either the bile or feces.

Variously substituted phenoxides (L) react with [Fe(PPIXDBE)]₂O (PPIXDBE is protoporphyrin IX di-tert-Bu ester dianion) to produce 5-coordinate high-spin complexes Fe(PPIXDBE)L which display spectroscopic properties similar to those of the Met form of the α mutant chain of Hb M Boston. The addition of pyridine or 1-methylimidazole (L') to Fe(PPIXDBE)L at 77 ^oK produced low-spin 6-coordinate complexes Fe(PPIXDBE)LL' which were studied spectroscopically. With the strongly basic 2,6-dimethoxyphenoxide (L), the above reaction was studied at 298 ^oK, where for L' = 1-methylimidazole the binding constant was approximately 100 M^-1 in CH₂Cl₂. The Fe(PPIXDBE)LL' complexes were made in an attempt to mimic the Fe(III) in the αchain of Met Hb M Iwate; however, the latter is high spin. With excess p-nitrophenoxide in CH₂Cl₂, Fe(PPIXDBE)(OC₆H₄-4-NO₂) forms Fe(PPIXDBE)(OC₆H₄ -4-NO₂)_2-, which exhibits a high-spin EPR spectrum at 77 ^oK. Addition of phenoxides or F- to Fe(II)

The biodistribution of ^99mTc-labeled glutathione in mice was dependent on the presence of Sn²⁺. The radioactivity ratio of the kidney to the liver increased from 1.17 to >6.0 as the Sn²⁺ ion concentration in the glutathione injection solution increased from 0 to 1.11 mM. The activity in the kidneys increased for the 1st 2 h and then decreased for 4 h. In the absence of the Sn²⁺, the radioactivity in the liver, kidney, and blood decreased 30 min after administration. Apparently, the reducing agent Sn²⁺ increases the retention of glutathione in the kidney.

A review, in Italian, with 82 references describing the properties, synthesis and biochemistry of pyrroles.