Journal of Porphyrins and Phthalocyanines

The synthesis of new metal-free and zinc(II), cobalt(II) phthalocyanines substituted with four 4-(2-N'-cyanoethyl)aminoethylsulfanyl groups is described. The new compounds have been characterized by elemental analysis and IR, ¹H NMR and UV-vis spectroscopy.

Soret-excited resonance Raman (RR) spectra are reported for some 40 nonplanar metalloporphyrin complexes. These include (i) copper β-octabromo-meso-tetra(para-X-phenyl)porphyrins, Cu[Br₈T(p-X-P)P] (X = CH₃, H, F, CF₃, NO₂); (ii) copper β-octachloro-meso-tetra(para-X-phenyl)porphyrins, Cu[Cl₈T(p-X-P)P] (X = H, CF₃); (iii) zinc β-octabromo-meso-tetraphenylporphyrin, Zn[Br₈TPP], and zinc β-octasubstituted meso-tetrakis(pentafluorophenyl)porphyrins, Zn[Y₈TPFPP] (Y = CH₃, Cl, Br); (iv) nickel β-octabromo-meso-tetra(para-X-phenyl)porphyrins, Ni[Br₈T(p-X-P)P] (X = CH₃, H, F, Br, COOMe, CF₃, NO₂), with and without bis-ligated axial pyridine and imidazole ligands; (v) nickel β-octachloro-meso-tetra(para-X-phenyl)porphyrins, Ni[Cl₈T(p-X-P)P] (X = CH₃, H, F, COOMe, CF₃, NO₂), again with and without bis-ligated axial pyridine ligands; and (vi) nickel octaethyltetraphenylporphyrin, Ni[OETPP], and palladium octaethyltetraphenylporphyrin, Pd[OETPP]. The spectra lead to the following conclusions. For a particular nonplanar porphyrin ligand, the high-frequency RR marker bands ν₂ and ν₄ downshift with increasing size of the coordinated metal ion, including a low- to high-spin transition for nickel porphyrins. In contrast, for a particular coordinated metal ion, these frequencies downshift with increasing nonplanarity of the porphyrin ligand, which in turn correlates with decreasing metal–nitrogen distances or the 'core size'. Similar results were also found for β-octaalkyl-meso-tetraphenylmetalloporphyrins by Shelnutt and coworkers. Thus, it appears that this complicated multiple-valued core size dependence of the high-frequency RR marker bands may be a generally shared property of all saddled metalloporphyrins. Variations in the electronic character of the metalloporphyrins resulting from variations in the para-substituents on meso-aryl groups do not result in significant shifts in the RR marker bands. The symmetric C_meso–C_phenyl stretching frequency (ν₁) at approximately 1240 cm^-1 is prominent in all the RR spectra except those of the low-spin Ni saddled porphyrins, for which they are relatively suppressed, and possible electronic-structural implications of this effect are discussed. In the low-frequency regions of the RR spectra of the compounds studied, the strongest band is roughly around 300 cm^-1 and appears to be relatively safely assignable as γ₁₆, a pyrrole tilting mode that strongly resembles the saddling mode in terms of atomic displacements.

Water-soluble phthalocyaninato zirconium(IV) and hafnium(IV) complexes have been synthesized for the first time. An increased solubility in comparison to PcZrCl₂ and PcHfCl₂ was caused by the introduction of gallic, 1,8-dihydroxynaphthalene-3,6-disulfonic (chromotropic), and 5-sulfosalicylic acids in the axial position. The new compounds were characterized by ¹H NMR, IR, UV-vis and elemental analysis.

A method is described for preparation of monosubstituted derivatives of platinum and palladium coproporphyrin-I. The method is based on chemical differentiation of one of the four alkoxycarbonyl groups of the starting coproporphyrin-I tetraalkyl ester by selective acid hydrolysis. The hydrolysis results after chromatographic purification to pure mono hydroxycarbonyl coproporphyrin, which can be subsequently coupled with a chemical species carrying a functional group of interest. The described method is used for preparation of phosphorescent metalloporphyrin labeling reagents having an isothiocyanato reactive group.

The cyclotetramerisation products from the 1,8-diazabicyclo[5,4,0]undec-7-ene catalysed reaction of a 1:1 mol mixture of 3,6-didecylphthalonitrile and 3,4-dicynopyridine in the presence of zinc chloride have been isolated by chromatography. The fractions comprise zinc octadecylphthalocyanine and compounds in which one, two, three and four pyridinoid rings replace the didecylbenzenoid moiety. The zinc bis(1,4-didecylbenzo)bis(3,4-pyrido)porphyrazine fraction was separated further into four sub-fractions and the components have been characterised by 400 MHz proton nuclear magnetic resonance spectroscopy, visible region spectroscopy, fluorescence spectroscopy and by cyclic voltammetry.

We describe the synthesis of tetrasulfonated silicon phthalocyanine and its oligomer product prepared by metal salt catalyzed polycondensation. The catalytic effect of H₂O-free CaCl₂ in quinoline is used for the polycondensation of dihydroxy silicon phthalocyanine to the cofacially arrayed oligomer. Spectroscopic characterization and photoelectron spectroscopy data of the prepared compounds are reported. We present the first results on polypyrrole films doped with these substances.

A total of 21 different porphyrins, some of them closely related to the photosensitizer meta-tetrahydroxyphenylchlorin (m-THPC) with a varied degree of hydrophilic/lipophilic substitution were synthesized employing conventional porphyrin condensation procedures and modern functionalization via organolithium reagents. For 14 of them, the photodynamic therapy (PDT) related photophysical properties were determined in isotropic solution and in liposome membrane-model systems. The photophysical data indicate that the localization of m-THPC may be fine-tuned by carefully changing the substitution pattern.