Oscar I. Koifman

A new water-soluble sulfonated cobalt(II) phthalocyanines: Synthesis, spectral, coordination and catalytic properties

Novel complexes of cobalt(II) with sulfonated derivatives of phthalocyanines are synthesized. The influence of the sulfonated groups number in peripheral substituent on solubility of macrocycle and ability to form ordered structures in solution is showed. Transition from H-aggregates to monomeric phthalocyanine structures and sandwich-type dimers was found during formation of metallophthalocyanine complexes with 1,4-diazabicyclo(2.2.2)octane. The catalytic activity of metallophthalocyanines was studied on the model of Merox process.

Porphyrazines with annulated diazepine rings 4: Synthesis and properties of MgII tetradiazepinoporphyrazine carrying exocyclic styryl fragments

A novel tetradiazepinoporphyrazine MgII complex bearing eight peripheral styryl substituents, [St8TDzPAMg(H2O)] (St = -CH=CHAr, where Ar = 4-methoxyphenyl) was prepared by template cyclotetramerization of the corresponding precursor — 5,7-distyryl substituted diazepino-2,3-dicarbonitrile — in the presence of MgII butoxide in n-butanol. UV-visible and 1H NMR spectral data indicate that the complex is strongly aggregated in non-coordinating solvents (dichloromethane, chloroform, benzene), it is dimeric in pyridine, whereas it is predominantly monomeric in dimethylsulfoxide and dimethylformamide. The fluorescence response is high for solutions in which the monomeric form is prevalent, but it is strongly quenched as the content of the dimer is increased. Evidence was obtained that dimerization occurs due to intermolecular hydrogen bonding between acidic CH2 groups in the diazepine ring (6H form) of one molecule with meso- and/or diazepine N atoms of another molecule, dimerization being also contributed by the presence of chlatrated water. In the presence of fluoride anions the dimer is destroyed with formation of the monomeric species, which is changed to the 1H form upon heating, as indicated by 1H NMR spectra.

Molecular structure and bonding in octamethylporphyrin tin(II), SnN4C28H28

Gas-phase electron diffraction was applied for the molecular structure determination of octamethylporphyrin tin(II), SnN(4)C(28)H(28), at the temperature of 706(10) K. The molecule was found to possess C(4v) symmetry with the Sn atom 1.025(30) Å above the plane of the N atoms and the following main internuclear distances (r(h1), Å): Sn-N = 2.301(9), C(α)-N = 1.360(8), C(α)-C(β) = 1.453(4), C(α)-C(m) = 1.395(4), C(β)-C(CH3) = 1.498(4). Quantum chemical calculations, DFT (B3LYP, BP86, PBE, PBE0) with cc-pVDZ, cc-pVTZ and cc-pVQZ basis sets reproduce the experimental bond distances with accuracy within 0.03 Å. According to NBO(B3LYP/cc-pVTZ) analysis, the direct donation gives a prevailing contribution to Sn-N bonding, decreasing the net charge on Sn from formal +2 to +1.28. The substitution effects at the pyrrole rings are discussed. The ability of different theoretical methods to predict the structure of this compound is analyzed.

Synthesis and spectral study of tetra(2,3-thianaphtheno)-porphyrazine, its tetra-tert-butyl derivative and their Mg(II), Al(III), Ga(III) and In(III) complexes

Starting from easily available thiophenols (PhSH (1a), 4-tert-butyl-PhSH (1b)) and oxalylchloride we have prepared 2,3-thianaphtenequinones 2a,b which were then successively converted to thianaphthene-2,3-dicarboxylic acids 4a,b their imides 10a,b, diamides 9a,b and finally to thianaphthene-2,3-dicarbonitriles 11a,b — the key precursors for the series of novel porphyrazines bearing four 2,3-annulated thianaphthene moieties. The free-bases 12a,b were obtained by cyclotetramerization of the dinitrile 11a,b in the presence of lithium in n-pentanol, while the reaction with magnesium(II) butoxide in n-butanol leads to the Mg(II) complex 13a. Complexes with Al(III) (14a,b), Ga(III) (14a,b) and In(III) (14a,b) were obtained by the template cyclotetramerization of the dinitriles 11a,b in a melt with the corresponding (hydroxy)acetates. Tetra(2,3-thianaphtheno)porphyrazine 12a and its metal complexes 13a–15a are only sparingly soluble in common organic solvents, the solubility is enhanced for their tert-butyl substituted derivatives 12b, 14b–16b. The study of the electronic absorbtion spectra has revealed that the extension of the porphyrazine π-chromophore by fusion of four thianaphthene fragments due to the angular type of their annulation (similar to that found in 1,2-naphthalocyanines) and negative inductive effect of the sulfur atoms has an effect on its spectral properties which is less than in the case of the isoelectronic naphthalene rings fusion and is comparable with the influence of four benzene rings in phthalocyanines.

Nanoaggregates in floating layers of azaporphyrins

An analysis of compression isotherms of floating layers of copper tetra-tert-butylphthalocyanine (CuPctBu4) and copper tetrabenzotriazaporphyrine, obtained at varied initial conditions, is carried out. The structure of layers is determined by three methods: the traditional one (direct estimation of area per molecule from a π-A isotherm), by a quantitative analysis of compression isotherms (with the use of Volmer equation), and by Brewster angle microscopy. It is shown that in layers with edge-on arrangement of molecules (initial surface concentrations N0 > 0.15 μmol.m-2), the layer structure, determined by the quantitative method, may differ drastically from the structure obtained by the traditional one. The equation of state of the floating layer generalized to the case when structural units of 2D gas are molecular aggregates is used to describe the layer of azaporphyrines. Boundaries of existence and characteristics of structure and properties of floating layers in stable states (size of nanoaggregates formed in a layer, number of molecules in them, interaggregate spacing, compressibility) are determined. The quantitative model of floating layer of copper tetra-tert-butylphthalocyanine is proposed. Constants characterizing a stable monolayer, as well as the region where it may be formed, are determined on the base of the model created.

Phosphorus(V) tetrapyrazinocorrolazines — first corrolazine derivatives with fused heterocyclic rings

Tetrapyrazinocorrolazines — first corrolazine derivatives with annulated heterocycles — have been prepared as phosphorus(V) complexes by the reaction of metal free tetrapyrazinoporphyrazines [(R8TPyzPA)H2] (R = Ph, Me) with phosphorus(III) chloride or bromide in pyridine. Oxophosphorus(V) complexes [(R8TPyzCA)P=O] were obtained when the reaction mixture was poured into water, while dilution with methanol leads to dimethoxyphosphorus(V) complexes [(R8TPyzCA)P(OMe)2]. The obtained compounds were characterized by MALDI-TOF mass-spectrometry and by IR, 1H, 31P NMR measurements. Their UV-vis spectral and basic properties in CH2Cl2–CF3COOH medium were studied in comparison to phosphorus(V) complex of octaphenylcorrolazine [(Ph8CA)P=O].

Perfluorinated porphyrazines 1: Synthesis and UV-vis spectral study of perfluorinated octaphenylporphyrazine and its indium(III) complex, [MPA(F5Ph)8](M = 2H, InIII(OH))

Novel perfluorinated porphyrazine has been prepared as indium(III) complex of octa(pentafluorophenyl)porphyrazine by cyclotetramerization of 1,2-dicyano-1,2-bis(pentafluorophenyl)-ethylene (mixture of cis- and trans-isomers) with basic indium(III) acetate in a melt. The InIII complex is stable in trifluoroacetic and sulfuric acids, but is easily demetalated with formation of the free-base in a chloroform solution containing HCl or slighly acidified with CF3COOH in the presence of tetraalkylammonium chloride as a catalyst. Perfluorination of octaphenylporphyrazine macrocycle leads to a hypsochromic shift of the Q-band maxima in the electronic absorption spectra, to drastic decrease of the basicity of meso-nitrogen atoms of porphyrazine macrocycle and to increase of the acidity of the internal NH-groups.

Kinetics and mechanism of the oxidation of dithiocarbamic acids in the presence of Co(II) phthalocyaninetetacarboxylic acid

The present work contains kinetic data of the oxidation of sodium diethyldithiocarbamate in the presence of phthalocyanine catalysts. It is shown that the nature of the peripheral substituent has a great influence on the self- - association of phthalocyanines and on their catalytic activity. A mechanism of the oxidation of sodium diethyldithiocarbamate involving the formation of a triple complex of the substrate, the reduced form of the catalyst and oxygen is offered. It is also shown that the oxidation mechanism of dithiocarbamic acids is different from that for cysteine.

The influence of molecular structure and π-system extent on nano- and microstructure of Langmuir layers of copper azaporphyrins

Comparative analysis of the structure of floating layers formed by copper tetra-tert-butylsubstituted phthalocyanine (CuPctBu4) and tetrabenzotriazaporphyrin (CuThptBu4) dissolved in a number of solvents is performed. The influence of the π-system extent (tetra-tert-butylsubstituted copper porphyrazine and phthalocyanine: CuPaztBu4 and CuPctBu4) on the structure of Langmuir layers of copper azaporphyrins is studied. It is shown that both the lack of one meso-atom and the increase of the extent of the π-system cause the balance between intermolecular interactions (AP–AP) — (AP-water) to shift to the latter and lead to formation of stable monolayers with the most open face-on structure of nanoaggregates instead of the edge-on one, all other factors being equal, in Langmuir layers prepared from solutions in aromatic solvents. The micro-level structural difference of copper tetra-tert-butylsubstituted porphyrazine (CuPaztBu4) and phthalocyanine (CuPctBu4) resulted from the structural difference of two-dimensional nanoaggregates forming the layers was shown using Brewster angle microscopy.

Symmetrical and difunctional substituted cobalt phthalocyanines with benzoic acids fragments: Synthesis and catalytic activity

Difunctional and symmetric phthalonitriles were synthesized by nucleophilic substitution of brome and nitro-group in 4-bromo-5-nitro-phthalonitrile for residues 4-amino-, 4-hydroxyl- and 4-sulfanyl benzoic acid. Symmetrical and difunctional substituted cobalt phthalocyanines were obtained by template synthesis based on mentioned phthalonitriles. Their spectral properties and catalytic activity in aerobic oxidation of sodium N,N-carbomoditiolate were investigated.