Investigation of Acidic and Coordination Properties of Octabromo-Substituted Porphyrins in the System of 1,8-Diazabicyclo[5,4,0]unde-7-ene-Acetonitrile

Acidity and metal ion coordination are described for three porphyrin derivatives, different in their macrocycle conformation and electronic substitution effects due to bromine substitution in pyrrole rings and trifluorometyl or phenyl groups in meso-positions. Combination of these facts allows modulating both steric and electronic effects on the macrocycle π-conjugated system. The role of electronic substitution effects in the macrocycle deprotonation and metal ion complex formation is found dominating with comparable resonance and inductive contributions, whereas non-planar conformation of reactive species contributes to the reaction rates to a lesser extent. The interaction of two single-electron (a_1ue_g) and (a_2ue_g) configurations is studied as a function of non-planar distortions of the molecular structure for the three tetrapyrrole compounds. The additive influence of disturbing factors on the configuration interaction of single-electron (a_1ue_g) and (a_2ue_g) configurations in the tetrapyrrole macrocycle is demonstrated.

     

Kinetic stability of tetra(1,2,5-thiadiazolo)porphyrazine in the system nitrogen-containing base-dimethyl sulfoxide

The behavior of tetra(1,2,5-thiadiazolo)porphyrazine in dimethyl sulfoxide has been studied, and fairly high stability of the resulting proton-transfer complex has been revealed. The complex is kinetically unstable in strongly basic media. The effects of the nitrogen-containing base and NH acidity of the porphyrazine macrocycle on the rate and activation parameters of decomposition of the proton-transfer complex have been estimated.     

Mesogenic 4-acryloyloxy- and 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates

Procedures were developed which made it possible to synthesize in good yields homologs of 4-acryloyloxyphenyl 4-alkoxybenzoates (C₃, C₅, C₇, C₈) and of 4-(2,3-epoxypropoxy)phenyl 4-alkoxybenzoates (C₅, C₇). The substituted phenylbenzoates obtained exhibit the enantiotropic nematic mesomorphism in a sufficiently wide temperature range. The studied compounds have absorption maxima in the near UV region and a high temperature of decomposition beginning.     

Synthesis of <Emphasis Type="Italic">meso</Emphasis>-phenyl-substituted porphyrins as starting compounds for the preparation of porphyrin-containing polymers

Data on the synthesis of symmetrical and unsymmetrical meso-phenyl-substituted porphyrins, which are building blocks for porphyrin-based polymers of different structure, are analyzed. Methods for the porphyrin ring construction and modification by active functional groups for further immobilization onto a polymer or preparation of porphyrin monomers are considered. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 680–703, April, 2007.     

Alkyl-substituted dipyrrylmethenes and their oxa- and thia-analogs: “structure—solvation properties” correlations

New data on the spectral properties and solution enthalpies of unsymmetrically substituted 2-(alkyl-2-pyrrolylmethylidene)methylpyrrolium bromides (or ,-dipyrrylmethene hydrobromides), their ,-, ,-isomers, as well as their oxa and thia analogs, that is, 2-(2-furylmethylidene)- and 2-(2-thienylmethylidene)-3,4,5-trimethyl-1H-pyrrolium bromides, in solutions of organic solvents of different nature are presented. A decrease in the number of substituents, as well as replacement of the heteroatom (N) in one five-membered ring of the dipyrrylmetnehe by oxygen or sulfur atoms cause a monotonic hypsochromic shift of absorption bands in the electronic absorption spectrum and weakening of the chromophore properties of the compounds. The chromophore properties of isomers are weakened from the ,- to ,- and ,-dipyrrylmethenes. Main trends in the influence of structural factors on the specific features of thermooxidative destruction of the above-mentioned compounds were analyzed.     

Study of acidity and coordination properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the system of 1,8-diazabicyclo[5.4.0]undec-7-ene-acetonitrile

Spectrophotometric titration method was used to study the acidic properties of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin in the presence of a deprotonated agent, 1,8-diazabicyclo[5.4.0] undec-7-ene, in acetonitrile. The spectral characteristics of the ionized forms and combined ionization constant for the first and second stages were revealed. The reaction of complex formation between the dianionic forms of 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin and zinc acetate was studied.     

Optical properties of Tl3SbS3 acousto-optic crystals

Optical properties of acousto-optical material Tl₃SbS₃ were investigated at the fundamental absorption edge. The basic (n = 1) and excited (n = 2, 3) exciton states were obtained from the λ-modulated reflection spectra for polarizations E⊥c at 10 K. Taking into account the spatial dispersion we determined the parameters of excitons by calculating the spectra shapes of λ-modulated reflection of line n = 1 and estimated values of the zone-translation masse and the reduced effective masse of excitons, the effective masse of electrons , heavy and light holes.     

Synthesis of tetraphenylporphines with active groups in the phenyl rings. 4. Functionally substituted monohydroxy derivatives of tetraphenylporphine

Monosubstituted porphyrins bonded to 8-hydroxyquinoline, -naphthalene, anthraquinone, and naphthoquinone residues, as well as dimeric porphyrins, were obtained by alkylation of monohydroxyphenyltriphenylporphines.See [1] for communication 3.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 781–786, June, 1987.     

Porphyrin acidity and metal ion coordination revisited: electronic substitution effects

Macrocycle acidity and Zn²⁺ ion coordination are reported for three porphyrin derivatives which differ in both steric and electronic substitution effects on the macrocycle π-conjugated system. The role of the electronic substitution effects in the macrocycle deprotonation and metal ion chelating was found to be dominating whereas the macrocycle nonplanar distortions contribute to the acidity and metal chelation rate of the studied porphyrins in less extent. The contributions of both resonance and inductive electronic substitution effects have been distinguished based on the relationship between the weighted sum of resonance and inductive Hammett constants and the acidity and metal ion chelation rate.