Synthesis and spectral properties of porphyrinquinone derivatives based on deuteroporphyrin IX

A series of diquinone derivatives of deuteroporphyrin IX, having different bond lengths between the chromophores, have been prepared. Deuteroporphyrin IX was condensed with modified hydroxyl-containing quinones by the mixed anhydride method. PMR spectroscopy was used to show that the magnetic anisotropy of the porphyrin ring has a strong effect on the chemical shift of the protons of the quinone ring and its neighboring substituents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 608–616, May, 1988.     

Supramolecular chirogenesis with bis-chlorin versus bis-porphyrin hosts: peculiarities of chirality induction and modulation of optical activity

[structure: see text] The complexation behavior, chirality induction and inversion in the achiral host, a racemic mixture of ethane-bridged bis(zinc octaethylchlorin) (1), and optical activity modulation in the chiral hosts, enantiopure 1(R) and 1(S), upon interaction with chiral and achiral amine guests have been investigated by means of the UV-vis, CD, and (1)H NMR techniques and compared with the corresponding spectral data of the bis-porphyrin analogue. It was found that the chirogenesis pathway is strongly dependent upon the structures of both major components (hosts and guests) of these supramolecular systems. Particularly, the distinct orientation of electronic transitions in the chlorin chromophores arisen from the reduced pyrrole ring, which makes it radically different from that of the porphyrin chromophores, and the size of the guest's substituents lead to the remarkable phenomenon of chirality induction-inversion in racemic 1 originating from the process of asymmetry transfer from enantiopure guests of the same homologous type and absolute configuration. This surprising chirogenic behavior is found to be in a sharp contrast to that observed in the analogous porphyrin-based systems. Furthermore, these structural and electronic phenomena also account for the effective optical activity quenching of enantiopure 1(R) and 1(S) upon interaction with chiral and with achiral amines, which results in formation of supramolecular complexes of opposite chirality.     

Porphyrins.

The synthesis of octaalkyl esters of 1,2-(meso-coproporphyrin-I-yl)ethane has been carried out from the corresponding copper complexes ofmeso-hydroxymethyl- and the nickel complexes ofmeso-dimethylaminomethylporphyrins. Their conversion into the correspondingtrans- andcis-ethylenebisporphyrins has been investigated. On boiling in AcOH or xylene, ethylenebisporphyrins form an equilibrium mixture ofcis andtrans isomers. The cis and trans isomers of 1,2-di(octaethylporphyrin-I-yl)ethylene and the octaethyl ester of 1,2-di(coproporphyrin-I-yl)ethylene have been isolated and their interconversions investigated. It was demonstrated by PMR that thecis isomers of ethylenebisporphyrins have a rigid structure in which there is no free rotation of the porphyrin rings. The presence of two atropisomers is also a characteristic of thecis isomer of the coproporphyrin-I derivative. The formation of metal complexes in combination with the preparation of complexes with additional ligands enables control of the conformation of ethanebisporphyrins in solution. A mechanism has been proposed for the oxidation of ethanebisporphyrins totrans-ethylenebisporphyrins in acetic and other lower aliphatic acids.For part 35 see [1]: for preliminary communications see [2, 3].Institute of Biomedicinal Chemistry, Russian Academy of Medical Sciences, Moscow 119832.Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki-shi, Osaka, 567, Japan. Queensland University of Technology. GPO Box 2434, Brisbane 4001, Australia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1627–1645, December, 1997.     

Synthesis of diquinone derivatives of deuteroporphyrin ix for the study of the first stage in the process of photosynthesis

Diquinone derivatives of deuteroporphyrin IX containing covalent bridges of different lengths between the chromophores have been synthesized. The compounds were prepared by the condensation of hydroxy-quinones with deuteroporphyrin IX using a mixed anhydride method which employed the system di-tert-butyl pyrocarbonate — 4-dimethylaminopyridine. A spectral study of the resulting porphyrin-quinones was carried out.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 176–182, February, 1992.     

Chiral Bis-chlorin: enantiomer resolution and absolute configuration determination

[structure: see text] A racemic mixture of the ethane-bridged bis(zinc octaethylchlorin) was successfully resolved for the first time to yield two enantiomers that exhibit substantial CD signals in the regions of chlorin B and Q transitions. The absolute configuration of the corresponding enantiomers was assigned and the origin of its high optical activity was rationalized through a combined spectral, crystallographic, and theoretical analysis.     

Integro-Local Limit Theorems for Compound Renewal Processes Under Cramér’s Condition. II

We prove the statements that are formulated in the first part of this paper. As an auxiliary proposition, we establish an integro-local theorem for the renewal measure of a two-dimensional random walk.     

Adsorption of water, diethyl ether, and acetonitrile on silicas with grafted perfluorohexyl coatings

The effect of the functionality of modifiers on the adsorption of vapors of compounds capable of strong specific interactions, including water, diethyl ether, and acetonitrile, on silicas with chemically grafted perfluorohexylsilanes (RSi(CH₃)_{3 −m} Cl _m , where m (functionality) is 1, 2, 3 and R is polyfluoroalkyl) was studied by adsorption under static conditions, gas chromatography, and IR spectroscopy. It was found that modification with monofunctional silane results in the most hydrophobic coating and a comparatively low-polarity surface with a strongly decreased contribution of specific interactions compared with other modifiers. Original Russian Text ? T.M. Roshchina, N.K. Shoniya, M.S. Lagutova, A.B. Nikol’skaya, V.Yu. Borovkov, L.M. Kustov, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 2, pp. 361–369.     

Express Voltammetric Control of Permanganate Ions in Process Solutions from Zinc Production

Express voltammetric analysis of zinc sulfate solutions for manganese(VII) ions was developed. The influence of the components of the supporting electrolyte on the measurement sensitivity and selectivity was studied. The method is intended for automated control of the permanganate treatment of the zinc electrolyte to remove cobalt(II) ions.     

First Passage Densities and Boundary Crossing Probabilities for Diffusion Processes

We consider the boundary crossing problem for time-homogeneous diffusions and general curvilinear boundaries. Bounds are derived for the approximation error of the one-sided (upper) boundary crossing probability when replacing the original boundary by a different one. In doing so we establish the existence of the first-passage time density and provide an upper bound for this function. In the case of processes with diffusion interval equal to ℝ this is extended to a lower bound, as well as bounds for the first crossing time of a lower boundary. An extension to some time-inhomogeneous diffusions is given. These results are illustrated by numerical examples.