Journal of Porphyrins and Phthalocyanines

A two dimensional colormap analysis program customized for phthalocyanines and related macrocyclic compounds has been developed in order to effectively visualize the atomic displacements from the mean plane. Eleven known phthalocyanine structures, including super- and subphthalocyanines, have been analysed as examples using the program, and the distribution of the skeletal deformations within the molecules surveyed.

Solid state properties of dicyano(2,3-naphthalocyaninato)cobalt(III) neutral radical crystal, [Co(2,3-Nc)(CN)₂]CH₃CN, were characterized by measurements of the resistivity under high pressure and under uniaxial strain, thermoelectric power, magnetic susceptibility, ESR and polarized reflectance spectra. The title compound exhibited thermally activated-type electrical conductivity along the c-axis. The room temperature (RT) resistivity ρ_RT along the c-axis and activation energy E_a rapidly decreased with increasing pressure. The temperature-dependent thermoelectric power S was that of a typical one-dimensional (1D) semiconductor. However the high absolute value of S suggested that this electronic system should be strongly correlated. Although the electrical resistivity exhibited monotonous temperature-dependence, the magnetic susceptibility clearly indicated a Peierls-type transition and marked fluctuation from RT. Both Peierls-type transitions and fluctuations are characteristic phenomena to 1D conductors. Furthermore ESR spectra manifested that the Peierls-type transition occurred at 100 K. The inconsistency between the electrical behavior (without a phase-transition) and magnetic behavior (with a phase-transition) indicates separation of the degrees of freedom in spin and charge (spin-charge separation) of this material. Spin-charge separation is a theoretically predicted phenomenon peculiar to the 1D conductors with strong correlation. The reflectance spectra were quantitatively explained by a 1D Hubbard model, and manifested the existence of a structural fluctuation of this material from RT. Based on these observed physical properties it is concluded that [Co(2,3-Nc)(CN)₂]CH₃CN is a strongly correlated 1D semiconductor with a Mott(Hubbard) type energy gap and characterised with a fluctuation and spin-charge separation.

The kinetics of the reaction of the tetrakis(1-methylpyridium-4-yl)porphyrin tetracation, [H₂(TMPyP)]⁴⁺, with gold(III) ions were studied along with equilibria of gold(III) species in aqueous medium at 25°C, I = 0.10 M (NaNO₃). The equilibrium constants for the formation of [AuCl_4-n(OH)_n]^- (n = 0,…,4), defined as β_n = [AuCl_4-n(OH)_n]^- [Cl^-]ⁿ / [AuCl₄^-][OH^-]ⁿ were found to be that logβ₁ = 7.94 ± 0.03, logβ₂ = 15.14 ± 0.03, logβ₃ = 21.30 ± 0.05 and logβ₄ = 26.88 ± 0.05. The overall reaction was first order with respect to each of the total [Au(III)] and [H₂TMPyP⁴⁺]. On the basis of pH dependence on rate constants and the hydrolysis of gold(III), the rate expression can be written as d[Au(TMPyP)⁵⁺]/dt = (k₁[AuCl₄^-] + k₂[AuCl₃(OH)^-] + k₃[AuCl₂(OH)₂^-] + k₄[AuCl(OH)₃^-])[H₂TMPyP⁴⁺], where k₁, k₂, k₃ and k₄ were found to be (2.16 ± 0.31) × 10^-1, (6.56 ± 0.19) × 10^-1, (1.07 ± 0.24) × 10^-1, and (0.29 ± 0.21) × 10^-1M^-1.s^-1, respectively. The kinetic data revealed that the trichloromonohydroxogold(III) species, [AuCl₃(OH)]^-, is the most reactive. The higher reactivity of [AuCl₃(OH)]^- is explained by hydrogen bonding formation between the hydroxyl group of [AuCl₃(OH)]^- and the pyrrole hydrogen atom of [H₂(TMPyP)]⁴⁺. Furthermore, applying the Fuoss equation to the observed rate constants at different ionic strengths, the apparent net charge of [H₂(TMPyP)]⁴⁺ was calculated to be +3.5.

The synthesis of new lipophilic meso-tetraarylporphyrins bearing cardanol is described; cardanol is both a dangerous pollutant and renewable, widely available, relatively low-cost natural material obtained as a byproduct of the cashew industry for the edible use of cashew kernel. Such compounds exhibited unusual chemical and physico-chemical properties.

Alcohols and phenols are tetrahydropyranylated in the presence of N,N',N″,N‴-tetramethyltetra-2,3-pyridinoporphyrazinato copper(II) in good to excellent yields under solvent-free conditions.

Photodynamic therapy (PDT) is one of the most effective treatments for cancer. We synthesized and characterized a series of 16 glycoconjugated porphyrins using a modification of the Lindsey method in the presence of Zn(OAc)₂·2H₂O as a template. The Zn²⁺ ion template strategy improved the yield about 3-fold in the case of meta-substituted tetraphenylporphyrins, and free-base porphyrins were obtaind almost quantitatively by demetalation with 4 M HCl. The hydrophobicity parameter (Log P) of these porphyrins was evaluated by reversed phase high-performance liquid chromatography (RP-HPLC). The Log P values ranged from +4.8 to +7.8, so that most of the compounds are amphiphilic. The effect of the glycopyranosyl unit on the hydrophobicity of these compounds is discussed on the basis of the Log P value.

3,4,5,6-tetrafluorophthalonitrile and 3,4,5,6-tetrachlorophthalonitrile were used as substrates with various phenoxides to prepare 3,4,6-trihalo-5-p-substitutedphenoxyphthalonitriles, containing four substituents other than hydrogen, by nucleophilic aromatic substitution reactions. Subsequent reactions with unsymmetrical catechols gave tetrasubstitutedphthalonitriles, having four different substituents. In one instance, attempts to displace the last remaining fluoro group by an octanoxide nucleophile led to substitution of a p-methylphenoxy group, showing that phenoxy substituents are also labile in nucleophilic aromatic substitution reactions on phthalonitriles. Alternatively, 4,5-dimethoxyphthalonitrile or 4,5-dineopentoxyphthalonitrile underwent electrophilic aromatic substitution reactions with dibromoisocyanuric acid to give their respective 3,6-dibromophthalonitriles. Coupling of these bromophthalonitriles with tri(n-butyl)phenylylethynyltin and tri(n-butyl)vinyltin in the presence of a nickel catalyst gave 4,5-dimethoxy-3,6-bisphenylethy nylphthalonitrile, 3-bromo-4,5-dimethoxy-6-phenylethynylphthalonitrile, 4,5-dineopentoxy-3,6-bisphenylethynylphthalonitrile, 3-bromo-4,5-dineopentoxy-6-phenylethynylphthalonitrile, 4,5-dimethoxy-3,6-vinylphthalonitrile and 3-bromo-4,5-dimethoxy-6-vinylphthalonitrile. Reductions in the coupling steps sometimes led to 4,5-dimethoxy-3-phenylethynylphthalonitrile and 4,5-dimethoxy-3-vinylphthalonitrile.

We report the characterization of sulfonated phthalocyanines using capillary electrophoresis and mass spectrometry. Derivatives investigated included the copper, cobalt, zinc and metal-free sulfonated phthalocyanines. In general, sulfonated phthalocyanines were found as aggregates in capillary electrophoresis separations, even at low concentration. Separations were much better at pH 9.0 than at pH 2.5. The addition of β-cyclodextrin did not alter the electropherograms significantly. The electropherograms of commercially available copper phthalocyanine-3,4',4″,4‴-tetrasulfonic acid and 4,4',4″,4‴-tetrasulfonic acid were very different, consistent with the latter compound having a structure that is not fully sulfonated. Matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) were used to characterize the sulfonated phthalocyanines. In general, MALDI gave better results than ESI. Mass spectral evidence was obtained for a pentasulfonated species of both the metal-free phthalocyanine and zinc phthalocyanine when these species were made by sulfonation of the metal-free phthalocyanine (followed by zinc insertion in the latter case). Sulfonated tetraphenylporphyrin derivatives were used as standards for mass spectrometry and to estimate the effect of net charge on the capillary electrophoresis migration time for sulfonated tetrapyrroles. Clean separation of the sulfonated tetraphenylporphyrin derivatives [5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenylporphyrin (TPPS3) and 5,10-bis(4-sulfonatophenyl)-15,20-diphenylporphyrin (TPPS2a)] was observed by capillary electrophoresis.

A multitechnique investigation of the determination of the order of magnitude of the second and third order NLO response of [5-[(4-dimethylaminophenyl)ethynyl]-15-[(4-nitrophenyl)ethynyl]-10,20-diphenylporphyrinato]nickel(II) (1) is reported with the aim to produce self consistent evidence for a significant NLO response of this kind of push-pull porphyrin chromophore. The experimental multitechnique approach is based on the EFISH technique, working with a non-resonant incident wavelength of 1.907 μm, on the solvatochromic method and finally on a vibrational method, avoiding any fluorescence or resonance interference. A theoretical MNDO-TDHF evaluation of the zero-frequency quadratic and cubic hyperpolarizabilities of an ab initio optimized planar structure is also reported. The order of magnitude of the quadratic hyperpolarizability of (1) at zero frequency (β₀), was found to be significantly lower than that reported for the corresponding Cu(II) or Zn(II) complexes with the same push-pull porphyrin chromophore.