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Cross cyclotetramerization of bis(4- tert-butylphenyl)fumaronitrile with 1,2,5-selenadiazole-3,4-dicarbonitrile in the presence of magnesium butoxide as template afforded a mixture of magnesium(II) porphyrazine complexes, from which magnesium complex of 5,6,8,9,11,12-hexakis(4- tert-butylphenyl)[1,2,5]selenadiazolo[3,4- b]porphyrazine was isolated by column chromatography and was subjected to demetalation on treatment with trifluoroacetic acid. The free ligand was found to undergo protonation at one meso-nitrogen atom in acid medium and deprotonation of one pyrrole ring to form monoanion by the action of bases. Reductive deselenation of the title compound with formation of vicinal diamino porphyrazine was studied by spectral and kinetic methods, and a mechanism involving two hydrosulfide ions was proposed. [ABSTRACT FROM AUTHOR]

Acid-base properties of Al(III), Ga(III), and In(III) complexes with tert-butyl-substituted thianaphthene-annulated porphyrazine and tetra(2,3-pyrazino)porphyrazine in proton-donor medium (CHCl-CFCOOH) were studied by spectrophotometric titration. The concentration stability constants of the singly protonated complexes were determined. The effects of the metal nature and aromatic heterocyclic fragment on the basicity of meso-nitrogen atoms were analyzed. Negative inductive effect of the sulfur atom in the thianaphthene fragment reduces the basicity of the meso-nitrogen atoms as compared to analogous porphyrazine and phthalocyanine complexes. Acid-base transformations of the thianaphthene-annulated tetra(2,3-pyrazino)porphyrazine involve both meso-nitrogen atoms and those in the pyrazine rings. [ABSTRACT FROM AUTHOR]

Cross cyclotetramerization of trans-2,3-diphenylbutanedinitrile with 1,2,5-thia(selena)diazole-3,4-dicarbonitriles or phthalodinitrile in the presence of magnesium butoxide gave mixtures of Mg(II) porphyrazine complexes which were treated with trifluoroacetic acid to isolate unsymmetrical hexaphenyl-substituted 1,2,5-thia(selena)diazolo-and benzo-fused porphyrazines together with diphenyltribenzoporphyrazine. Their 1H NMR and electronic absorption spectra (in the UV and visible regions) were recorded. The effect of benzene and heteroring fusion on the electronic and steric structure and spectral properties of porphyrazine derivatives was studied in terms of the molecular orbital perturbation theory and semiempirical quantum-chemical calculations (AM1, PM3, ZINDO/S, CNDO/S). [ABSTRACT FROM AUTHOR]

The effect of tetra-β-phenyl substitution on the acid-base properties of the porphyrazine macroring was studied by theoretical and experimental methods. [ABSTRACT FROM AUTHOR]

Indium complex of 13,17-dibutyl-2,3,7,8,12,18-hexamethyl-5-azaporphyrin (Cl)InMAP was synthesized, and acid-base interactions of themeso-nitrogen atoms in (Cl)InMAP and its diaza analog (Cl)InDAP with acetic and trifluoroacetic acids were studied by1H NMR and electronic spectroscopy. Depending on the medium, the complexes and proton-donor species HA give rise to acid solvates>N···(HA)n which are converted to final acid-base interaction products, H-complexes>N···H+···A-(HA)m or ionic associates>NH+···A-(HA)l , as the acidity of the medium rises. In acetic acid solution, the acid solvates derived from more basic (Cl)InMAP exist in equilibrium with the H-associates (pKa1 = 4.45±0.03). From (Cl)InDAP, the corresponding H-associates are formed only in the presence of H2SO4 (pKa1 = 2.10±0.03). In more polar media (solutions of trifluoroacetic acid in methylene chloride), ionic associates are formed, which involve one [(Cl)InMAP, pK1 = 2.46±0.02] or twomeso-nitrogen atoms [(Cl)InDAP, pK1 = 2.11±0.03, pK2 = 0.41±0.04). [ABSTRACT FROM AUTHOR]

Nucleophilic substitution of fluorine atoms in the phenyl rings by alkoxy groups was performed in perfluorosubstituted zinc(II) octaphenylporphyrazine [ZnPAF40]. Up to 12 fluorine atoms are substituted in the reaction with sodium butoxide in boiling butanol leading to the formation of [ZnPAF40-n(OBu)n] (n = 6-12). Up to eight monosaccharide groups are introduced in the reaction with 1,2:3,4-di-O-isopropylidene-α-D-galactopyranose (Gal´) in toluene in the presence of sodium hydride leading to the formation of [ZnPaF(40-n)(Gal´)n] (n = 6-8). It was possible to obtain a water-soluble glycoconjugated zinc(II) porphyrazine [ZnPaF(40-n)(Gal)n] after removal of the isopropylidene protecting groups by treatment with trifluoroacetic acid. Substitution products are characterized by electron absorption spectroscopy, NMR spectroscopy, and mass spectrometry. Substituting the fluorine atoms with monosaccharide residues leads to an increase in the fluorescence quantum yield from ФF = 0.19 for [ZnPAF40] to 0.29 for [ZnPA(Gal´)nF40-n] (n = 6-8). [ABSTRACT FROM AUTHOR]

In this review, we generalize the research results obtained by Russian scientists in the last 10-15 years for porphyrins, related compounds, and their metal complexes with a pronounced application potential. The main attention is paid to the analysis of relationships between the spectral, catalytic, and sensor properties of tetrapyrrole compounds and the structure of peripheral substituents and axial ligands and the nature of the coordinating metal atom. [ABSTRACT FROM AUTHOR]

The article focuses on a study related to examining the acid-base properties, deselenation and synthesis of 5,6,8,9,11,12-Hexakis(4-tert-butylphenyl)[1,2,5]selenadiazolo[3,4-b]porphyrazine, a macrocyclic compound, published in a 2013 issue of the "Russian Journal of Organic Chemistry."

Quantum-chemical calculations for series of porphin (H2P) and porphyrazine (H2PA) derivatives whose molecules contain a 3,4-annulated five-membered heteroaromatic ring of pyrrole, furan, and thiophene as well as 1,2,5-triazole, 1,2,5-oxadiazole, and 1,2,5-thiadiazole have been carried out by the AM1 and INDO/Sm methods (m means “modified parametrization”). As follows from the unrestricted Hartree-Fock AM1 calculations, the ground state energy of the a isomer is lower than that of the b isomers for all compounds, the a and b isomers being NH isomers with the additional five-membered ring fused to a pyrrolenine or pyrrole ring, respectively. Condensation of the five-membered ring for the b isomers of the H2P derivatives is shown to extend the main conjugation path from 18-membered to 21-membered cyclopolyene. However, the 18-membered cyclopolyene for the a isomers of the H2P derivatives and 16-membered cyclopolyene for both isomers of the H2PA derivatives prove to be isolated from the five-membered ring carrying six π-electrons. Based on INDO/Sm computations of electronic absorption spectra of the H2P and H2PA derivatives, it is shown that the Qx level of the a isomers is sensitive to the nature of the annulated ring whereas the Qy level is practically not shifted. On the contrary, the Qx level of the b isomers is relatively insensitive to the nature of the annulated ring while the Qy level decreases monotonously in the H2P and H2PA series, being the first excited state level for the majority of the derivatives (X is along the NH-HN axis; Y, perpendicular to it). The electronic absorption spectra at the border of the visible and near-UV regions are determined mainly by two high-intensity G → Bx and G → By transitions for the H2P derivatives. However, four intense G → Bx, G → By, G → Nx, and G → Ny transitions are characteristic of the spectra of the H2PA derivatives. [ABSTRACT FROM AUTHOR]

Basic properties of tri(4- tert-butylbenzo)[ b,g,l](1,2,5-thiadiazolo)[3,4-q]porphyrazine and its Cu complex in the H2SO4-CH3COOH medium were studied by means of spectrophotometric titration. It was found that in going from an acetic acid solution 100% H2SO4 the complete acid-base interaction consecutively involves all the four meso-nitrogen atoms of the porphyrazine macroring, as well as one of the nitrogen atoms of the 1,2,5-thiadiazol fragment. The stability constants of the resulting acid forms were determined and compared with the gas-phase proton affinities calculated by the AM1 method. Annulation of a 1,2,5-thiadiazole fragment to the porphyrazine macroring increases the basicity of the 1,2,5-thiadiazole nitrogen atoms and decreases the basicity of macroring meso-nitrogen atoms. [ABSTRACT FROM AUTHOR]

Cross cyclotetramerization of 1,2,5-thiadiazole-3,4-dicarbonitrile and 4- tert-butylphthalodinitrile in the presence of magnesium butoxide gave a mixture of symmetric and asymmetric porphyrazine magnesium(II) complexes. One of these, (22(3),72(3),122(3)-tri- tert-butyltribenzo[ b,g,l][1,2,5]thiadiazolo[3,4- q]-5,10,15,20-tetraazaporphyrinato)magnesium(II) (MgSBBB), was isolated by column chromatography and was treated with trifluoroacetic acid to obtain the corresponding free ligand (H2SBBB). The effect of the mode of heteroring fusion on the electronic absorption spectra of tribenzoporphyrazines was studied. [ABSTRACT FROM AUTHOR]

Tetraphenyltetraazaporphyrin was reacted with bromine in trifluoroacetic acid to obtain tetrakis(4-bromophenyl)tetraazaporphyrin. The latter forms with pyridine and dimethyl sulfoxide proton-transfer complexes which differ from each other by the degree of proton transfer from the NH acid to base. [ABSTRACT FROM AUTHOR]

Absorption, fluorescence, and phosphorescence spectra of metal complexes of 4-tert-butylphenyl-substituted tetra(1,4-diazepino)porphyrazine MPADz4Ph8′ (M = Mg, Zn; PA = porphyrazine; Dz = diazepine; Ph = phenyl; Ph′ = 4-tert-butylphenyl) were recorded in DMF at 293 and 77 K. The Q(0–0) absorption bands of MgPADz4Ph8′ and ZnPADz4Ph8′ did not show signs of splitting, i.e., corresponded to the monomeric form. Singlet–triplet gaps of 4700 cm–1 for the Mg complex and 4800 cm–1 for the Zn complex were determined from fluorescence and phosphorescence spectra. Fluorescence quantum yields and lifetimes were measured. Rate constants of S1,2 → S0 radiative transitions and total rate constants of nonradiative deactivation of the S1,2 states were determined. Internal conversion rate constants were estimated. Conformer geometries of MgPADz4Ph8 (in the 6H tautomeric form) were calculated by density functional theory in the PBE/TZVP version. The conformer of symmetry S4v (D2d) had the lowest energy. Nonplanar diazepine rings induced small but perceptible out-of-plane distortions in the central porphyrazine ring of MgPADz4Ph8. This feature correlated with the observed Stokes shifts of 400 and 350 cm–1 (at 293 K) for MgPADz4Ph8′ and ZnPADz4Ph8′ whereas the metal phthalocyanines had shifts of ~50 cm–1. Excited electronic states of MgPADz4Ph8 were calculated using INDO/Sm. The Q-state energy of 15,200 cm–1 agreed well with the observed value of 14,800 cm–1. Strong featureless absorption in the range 330–450 nm (Soret band analog) with maxima at ~25,000 and ~29,000 cm–1 was due mainly to two strong electronic transitions with calculated energies of 24,100 and 31,500 cm–1; a shoulder on the long-wavelength side of the Soret band at ~23,000 cm–1, to a transition of calculated energy 23,800 cm–1. [ABSTRACT FROM AUTHOR]

We have fabricated and tested tandem photovoltaic cells containing series-connected subcells of the 'oxide-organic semiconductor-metal' type. The organic semiconductors were two phthalocyanine dyes (SubPc and PcVO); Al or Ag:Mg were used as capping metallic electrodes. A semitransparent composite metal-oxide layer formed by molybdenum oxide MoO deposited over an ultrathin Al layer is used to join the subcells. Additionally, a MoO layer deposited onto glass/ITO substrates serves as an anode buffer in the front subcell, and LiF deposited onto the dye layers serves as a cathode buffer in the front or rear subcells. Upon optimization of the thickness and composition of the intermediate layer, the open circuit voltage U amounts to 1.6 V reflecting total summation of the contributions from the each of the subcells at a wide spectral coating from 300-1000 nm. The fill factor in the tandem cell is not worse than in individually made single cells with the same scheme or in disconnected subcells. [ABSTRACT FROM AUTHOR]

We have performed complex experimental and theoretical investigations of the spectral-luminescent properties and electronic structure of new phthalocyanine analogs, Mg octaphenylporphyrazine and its derivatives with an annulated thiadiazole or selenadiazole ring instead of two phenyl groups. Fluorescence characteristics have been determined at 293 and 77 K: emission, excitation, and fluorescence polarization spectra; fluorescence quantum yield φ, and lifetime τ. Annulation of a five-membered chalcogen-containing heterocycle leads to splitting of the long-wavelength absorption band Q(0-0) and to the bathochromic shift of its longest wavelength component Q(0-0), which increase upon passage from S to Se. At the same time, the fluorescence quantum yield φ and lifetime τ decrease, which is related to the intramolecular heavy-atom effect. The geometric structure of the ground state of the Mg porphyrazine molecules has been determined based on the density functional theory (DFT), and excited electronic states have been calculated with modified parametrization of the INDO/S method, INDO/Sm. Semiquantitatively, the calculated level positions of the lowest Q states and spectral shifts of Mg octaphenylporphyrazine and S-derivative agree with experimental data. For the range of the Soret band, calculated transition energies and their intensity distributions substantially depend on the dihedral angle γ between a phenyl ring and porphyrazine macrocycle. We show that, based on calculations at the angle γ = 60°, bands in the observed absorption spectra can be assigned with an accuracy of ∼2000 cm. [ABSTRACT FROM AUTHOR]

Spectral and luminescent properties of a new phthalocyanine analog, the magnesium complex of diphenyl substituted mono(1,4-diazepino)tribenzoporphyrazine, have been studied at 293 and 77 K. The results have been explained on the basis of quantum-chemical calculations for both this molecule and its simpler analogs with respect to 6 H/1 H-isomerism of the 1,4-diazepine ring. The small difference between the ground-state energies for the 6 H and 1 H isomers makes tautomerism between them possible. It is shown that the electronic transitions with intramolecular charge transfer from the diazepine fragment to the macrocycle have relatively low energy, especially for the 1 H isomers. These states can be of considerable importance for photophysical and photochemical processes. A comparison of the theoretical and experimental electronic absorption spectra has confirmed that the diazepine ring in the substituted Mg-diazepinoporphyrazine is present in the 6 H-form. It is established that substitution of one benzene ring by a diazepine fragment leads to quenching of fluorescence, decreasing its quantum yield to 27% (for Mg-phthalocyanine 76%). [ABSTRACT FROM AUTHOR]