Cotton-mouton constants and spatial structure of 2,2′- and 4,4′-dipyridyls and their salts in solutions

Magnetic birefringence has been used in studying the spatial structure of a series of dipyridyl derivatives in hydrochloric acid solutions, and also some of their quaternary salts in water. It has been shown that when the change is made from the molecular forms of the 2,2- and 4,4-dipyridyls to their protonated mono and bis derivatives, the angles of rotation of the aromatic rings are very little changed; in the methylated cation, the degree of acoplanarity increases.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, pp. 2771–2775, December, 1991.     

Sequence-based analysis of 5′UTR and coding regions of CASP3 in terms of miRSNPs and SNPs in targetting miRNAs

Apoptosis is described as a mechanism of cell death occurring after adequate cellular harm. Deregulation of apoptosis occurs in many human conditions such as autoimmune disorders, ischemic damage, neurodegenerative diseases and different cancer types. Information relating miRNAs to cancer is increasing. miRNAs can affect development of cancer via many different pathways, including apoptosis. Polymorphisms in miRNA genes or miRNA target sites (miRSNPs) can change miRNA activity. Although polymorphisms in miRNA genes are very uncommon, SNPs in miRNA-binding sites of target genes are quite common. Many researches have revealed that SNPs in miRNA target sites improve or decrease the efficacy of the interaction between miRNAs and their target genes. Our aim was to specify miRSNPs on CASP3 gene (caspase-3) and SNPs in miRNA genes targeting 5′UTR and coding exons of CASP3, and evaluate the effect of these miRSNPs and SNPs of miRNA genes with respect to apoptosis. We detected 141 different miRNA binding sites (126 different miRNAs) and 7 different SNPs in binding sites of miRNA in 5′UTR and CDS of CASP3 gene. Intriguingly, miR-339-3p’s binding site on CASP3 has a SNP (rs35372903, G/A) on CASP3 5′UTR and its genomic sequence has a SNP (rs565188493, G/A) at the same nucleotide with rs35372903. Also, miR-339-3p has two other SNPs (rs373011663, C/T rs72631820, A/G) of which the first is positioned at the binding site. Here, miRSNP (rs35372903) at CASP3 5′UTR and SNP (rs565188493) at miR-339-3p genomic sequence cross-matches at the same site of binding region. Besides, miR-339-3p targets many apoptosis related genes (ZNF346, TAOK2, PIM2, HIP1, BBC3, TNFRSF25, CLCF1, IHPK2, NOL3) although it had no apoptosis related interaction proven before. This means that miR-339-3p may also have a critical effect on apoptosis via different pathways other than caspase-3. Hence, we can deduce that this is the first study demonstrating a powerful association between miR-339-3p and apoptosis upon computational analysis.     

Study of the fluorescence of 9,9′-bianthryl in polyvinylalcohol and in polyvinylchloride at 300 K and 80 K

By UV-vis spectroscopy and use of the polarization of the emission, we show that the 9,9′-bianthryl (9,9′BA) symmetrical molecule exhibits an induced fluorescence in polyvinylalcohol (PVA) by hydrogen bonding of the type OH⋯π which depends on considered temperature. This anomalous behaviour does not occur when this molecule is included in a polyvinylchloride, aprotic polymer.     

Thermodynamics of the solvation and phase distributions of 2,2′-dipyridyl in acetonitrile-DMSO-hexane and methanol-DMSO-hexane systems

The Gibbs energies of 2,2′-dipyridyl when transferred from dimethyl sulfoxide to its mixtures with acetonitrile and methanol are determined from the distribution of substance between immiscible phases. It is found that moving from dimethyl sulfoxide to acetonitrile and methanol weakens the solvation of 2,2′-dipyridyl due to a change in the solvation of amino groups and the hydrocarbon substituent, which is reflected in a reduction in the entropy component of the Gibbs energy.     

The structure of 6,6′-biquinolyl and its dication in solution

Conformational analysis of 6,6-biquinolyl and its dication was performed using dipole moments and data from electric and magnetic birefringence. The rotation angles between the quinoline rings for thecis- andtrans-conformers in solution are 50°. The emergence of positive charges on both heteroaromatic rings does not result in noticeable changes in the spatial structure.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 330–332, February, 1994.     

Re-examination of 7,7′-dimethyl-7-germanorbornadiene photocleavage in solution and in organic glasses

Dimethylgermylene and its Ge=Ge doubly bonded dimer, tetramethyldigermene, have been characterized directly in solution by 308-nm laser flash photolysis in n-hexane solution, as well as 254-nm photolysis in hydrocarbon glasses at t = 77 K. An absorption band maximum of λ _max ≈ 430 nm and molar absorption coefficient of ε ≈ 2,700 M⁻¹ cm⁻¹ have been shown to be attributable to low-temperature glasses, while the absorption band maximum of λ _max ≈ 480 nm and molar absorption coefficient of ε ≈ 2,400 M⁻¹ cm⁻¹ have been shown to be related to dimethylgermylene in n-hexane solution. The molar absorption coefficient of tetramethyldigermene (λ _max ≈ 380 nm) was determined to be ε ≈ 84,000 M⁻¹ cm⁻¹. The germylene is formed via (formal) cheletropic photocycloreversion of 7,7′-dimethylgerma-1,4,5,6-tetraphenyl-2,3-benzo-norbornadiene. Tetramethyldigermene and 1,2,3,4-tetraphenylnaphthalene in the triplet state were formed, together with dimethylgermylene. We attempted to explain the various contradictory interpretations of experimental data existing in the literature on this reaction.     

Experimental measurement and modelling of solubility of inosine-5′-monophosphate disodium in pure and mixed solvents

The solubility of biological chemicals in solvents provide important fundamental data and is generally considered as an essential factor in the design of crystallization processes. The equilibrium solubility data of inosine-5′-monophosphate disodium (5′-IMPNa₂) in water, methanol, ethanol, acetone, as well as in the solvent mixtures (methanol + water, ethanol + water, acetone + water), were measured by an isothermal method at temperatures ranging from (293.15 to 313.15) K. The measured data in pure and mixed solvents were then modelled using the modified Apelblat equation, van’t Hoff equation, λh equation, ideal model and the Wilson model. The modified Apelblat equation showed the best modelling results, and it was therefore used to predict the mixing Gibbs free energies, enthalpies, and entropies of 5′-IMPNa₂in pure and binary solvents. The positive values of the calculated partial molar Gibbs free energies indicated the variations in the solubility trends of 5′-IMPNa₂. Water and ethanol (in the binary mixture with water) were found to be the most effective solvent and anti-solvent, respectively.     

Pulse radiolysis studies of etoposide and 4′-demethylepipodophyllotoxin in aqueous solution

The reactions of etoposide (VP 16, 4′-demethyl-epipodophyllotoxin ethylidene-β-d-glucoside) and 4′-demethylepipodophyllotoxin (DMEP) with the primary radiolytic products of water, such as e⁻_aq, H and OH/O⁻ radicals, and the secondary radical (SO⁻₄) in aqueous solution were studied by use of the techniques of pulse radiolysis, respectively. The absorption spectra of reaction products with e⁻_aq, H and OH/O⁻ and SO⁻₄ radicals were observed, and the rate constants of them were determined by following the build-up kinetics of radicals produced or the decay of hydrated electron observed at 600 nm, respectively.     

Studies in the area of 2,3′-biquinolyl. 1. Arylation and hetarylation of 2,3′-biquinolyl dianion

The 2,3-biquinolyl dianion, when reacting with aryl- and hetaryl halides, forms arylation products at the 4 position, and treatment of these products with alkyl halides or water yields 1-alkyl-4-aryl-1,4-dihydro-2,3-biquinolyls or 4-aryl-1,4-dihydro-2,3-biquinolyls, respectively. Oxidation of the latter yields 4-aryl-2,3-biquinolyls. The cation dependence of the arylation reaction is demonstrated.Stavropol' State University, Stavropol' 355009. Russian Chemical Engineering University, Moscow 125190. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1094–1099, August, 1997.     

Synthesis of 2′-hydroxychalcones and related compounds in interfacial solid-liquid conditions

A general synthetic method of 2′-hydroxychalcones and 2′-hydroxyphenyl-(2-alkylvynyl) ketones in interfacial solid-liquid conditions, is described. No secondary reactions were observed. The interfacial mechanism is discussed by means of the structure of active sites of solid.     

Calorimetric study of 2′-methylacetophenone and 4′-methylacetophenone

Values of the condensed phase standard (p = 0.1 MPa) molar enthalpy of formation for 2′- and 4′-methylacetophenones were derived from the standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The values of the standard molar enthalpy of vaporization, at T = 298.15 K, were measured by Calvet microcalorimetry. Combining these two values, the following enthalpies of formation in the gas phase, at T = 298.15 K, were then derived: 2′-methylacetophenone, –(115.7 ± 2.4) kJ · mol⁻¹, and 4′-methylacetophenone, –(122.6 ± 2.4) kJ · mol⁻¹. Substituent effects are discussed in terms of stability and compared with other similar compounds. The value of the standard molar enthalpy of formation for 3′-methylacetophenone was estimated from isomerization schemes.     

Crystal Structure of Derivative of H_4′-NOBIN and the Applications in Hetero-Diels-Alder Reaction

Novel Schiff bases of H4′-NOBIN 5a and 5b were synthesized by condensation of 3 with aldehydes. Compound 5b was structurally characterized by single-crystal X-ray diffraction. The asymmetric hetero-Diels-Alder reactions were carried out with high yields and good enan-tioselectivities in the presence of Ti-(S)-5a complex as catalyst. Crystallographic data for 5b: C27H22BrNO, Mr = 456.37, triclinic, space group P1 with a = 9.1618(2), b = 10.3836(2), c = 12.7718(2), α = 105.4860(10),β = 94.6360(10), γ = 108.4610(10)o, V = 1092.32(4)3, Z = 2, Dc = 1.388 g/cm3, μ = 1.900 mm-1, F(000) = 468, R = 0.0476 and wR = 0.1248 for 3092 observed reflections (Ⅰ > 2σ(Ⅰ)).     

Complex Formation of Hematoporphyrin with Cyclodextrins and 1,1′-Diheptyl-4,4′-bipyridinium Dibromide in Aqueous Solutions

At around 5×10^-6?mol?dm^-3 of hematoporphyrin (HP), an HP dimer exists as well as an HP monomer. The equilibrium constant for the dimerization of HP in pH 10.0 buffer has been evaluated to be 1.70×10⁵?mol^-1?dm³ from the HP concentration dependence of the absorption spectrum. In aqueous solution, HP forms 1:1 inclusion complexes with β-cyclodextrin (β-CD), γ-cyclodextrin (γ-CD), and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD). The fluorescence of HP is significantly enhanced by the addition of CDs. From simulations of the fluorescence intensity changes, the equilibrium constants for the formation of the CD–HP inclusion complexes have been estimated to be 200, 95.7, and 938?mol^-1?dm³ for β-CD, γ-CD, and TM-β-CD, respectively. HP forms a 1:1 complex with 1,1′-diheptyl-4,4′-bipyridinium dibromide (DHB) in aqueous solution. In contrast to the addition of CDs, the HP fluorescence is significantly quenched by the addition of DHB. The equilibrium constant for the formation of the HP–DHB complex has been evaluated to be 1.98×10⁵?mol^-1?dm³ from the fluorescence intensity change of HP. The addition of DHB to an HP solution containing β-CD induces a circular dichroism signal of negative sign, indicating the formation of a ternary inclusion complex involving β-CD, HP, and DHB. In contrast, there is no evidence for the formation of a ternary inclusion complex of HP with DHB and TM-β-CD.     

Preparation of 6,6′—Bisperfluoroalkylated BINOLs and Their Application in Asymmetric Alkylation of Benzaldehyde

6，6′-Bis(1H,1H,2H,2H-perfluorooctyl)-BINOL and 6,6′-bis(1H,1H,2H,2H-perfluorodecyl)-BINOL were synthesized through Suzuki coupling reaction and used in fluorous biphase asymmetric alkylation of benzldehyde,Good enantioselectivity was obtained and the catalysts could be recovered by liquid-liq-uid extraction.     

Mechanism of the reaction of 1,1′-diethylferrocene and decamethylferrocene with peroxides in organic solvents

Kinetic relationships of oxidation of 1,1′-diethylferrocene and decamethylferrocene with peroxides ROOR (R = H, t-C₄H₉) in organic solvents were studied and the composition of oxidation products was established. It is shown that reactivity of (C₅H₄C₂H₅)₂Fe is significantly lower than that of Cp*₂Fe [Cp* = η⁵-C₅(CH₃)₅] which is seen from the ability of the first metal complex to undergo oxidation with a notable rate only in the presence of Brønsted acids, whereas the second substance is oxidized both in the presence and in the absence of these acids. Two possible mechanisms of oxidation of metal complexes in the presence of strong acids are discussed. One of them is based on the ability of ferrocene to fast and equilibrium protonation with the formation of Cp₂Fe⁺—H structure. Another one considers the ability of metal complexes to coordinate peroxides with the formation of weakly bound charge transfer complexes of the composition Cp₂Fe^δ+·ROOR^δ-. The possibility of their formation is confirmed by the oxidation of Cp₂Fe with hydroperoxides in the absence of acids.