Dimeric Cholaphanes with Oxamide Spacers

Summary. Two new dimeric cholaphanes with oxamide spacers were prepared. The spacers bind two identical steroidal subunits through positions 3,3′ and 24,24′ (head-to-head dimer) or positions 3,24′ and 3′,24 (head-to-tail dimer).     

New Acyclic Dimers of Cholic Acid with Oxamide and Hydrazide Spacers

Summary. Three new acyclic dimers of cholic acid with oxamide and isomeric hydrazide (N,N′-diacylhydrazine) spacers were obtained. The oxamide spacers bind two identical steroidal subunits through position 3 (head-to-head dimer) or position 23 (tail-to-tail dimer). In the case of a third dimer the hydrazine moiety binds two molecules of cholic acid through position 24 (tail-to-tail dimer).     

New Acyclic Dimers of Cholic Acid with Oxamide and Hydrazide Spacers

Three new acyclic dimers of cholic acid with oxamide and isomeric hydrazide (N,N′-diacylhydrazine) spacers were obtained. The oxamide spacers bind two identical steroidal subunits through position 3 (head-to-head dimer) or position 23 (tail-to-tail dimer). In the case of a third dimer the hydrazine moiety binds two molecules of cholic acid through position 24 (tail-to-tail dimer).     

Effects of the nature of counterions in solution on interactions of phenoxazones, xanthones, and carbazoles containing benzo-crown groups with DNA

The interactions of DNA with phenoxazones, xanthones, and carbazoles containing the (benzo-18-crown-6)-4′-yl and (benzo-15-crown-5)-4′-yl radicals bonded to the chromophore via spacers of different lengths in the presence of Na⁺ and K⁺ ions were studied by spectrophotometry, circular dichroism, and dynamic birefringence. The thermodynamic parameters of the binding of the compounds with DNA and changes in the macromolecular parameters of the DNA molecule during complexation were determined. Based on the results of these studies, we suggested the models of bonding of these compounds to the double helix of DNA. It is shown that the mode of DNA binding with a phenoxazone derivative containing two (benzo-15-crown-5)-4′-yl radicals bonded via a fragment of glycine to chromophore depends on the type of the counterion in solution. In the presence of Na⁺, the chromophore is intercalated into the double helix of DNA; in the presence of K⁺, it is bound to DNA in the form of a dimer outside the double helix. The type of the counterion does not affect the mode of binding of other crown-containing compounds of actinocin with DNA. For compounds containing the (benzo-18-crown-6)-4′-yl radical, the mode of binding to DNA adepends only on the spacer length.     

UV/Vis Spectral Study of the Self-aggregation of Pinacyanol Chloride in Ethanol–Water Solutions

The concentration dependent self-aggregation of 1,1′-diethyl-2,2′-carbocyanine chloride (pinacyanol chloride dye) in 7.5% (v/v) ethanol + 92.5% water solution in the range of 10⁻⁶–10⁻³ mol⋅dm⁻³ has been investigated by quantitative UV/vis and derivative spectroscopy. Bands with maxima at 601, 546, 522, and 507 nm could be attributed, respectively, to the monomer, a sandwich-type dimer, a vibronic overtone of the dimer, and a higher aggregate, most probably a stacked trimeric form of the dye. Using the PeakFit program, the overlapping bands were separated and analyzed for all concentrations studied. From the spectral fitting routine, extinction coefficients of 192,000, 156,000, and 282,000 cm⁻¹⋅mol⁻¹⋅dm³ were determined for the monomer, dimer and trimer respectively.     

peri-naphthylenediamines

First indirect evidence for the formation of a radical cation of 1,8-bis(dimethylamino)naphthalene (“proton sponge”) in reactions with HNO₃, HNO₂, NO₂, and I₂ has been obtained. In all cases, the products of reaction of the radical cation with nucleophiles and/or its dimer, 4,5,4′,5′-tetrakis(dimethylamino)-1,1′-binaphthyl, have been isolated. 4-Chloro-1,8-bis(dimethylamino)naphthalene has been regioselectively synthesized in high yield. For Part 24, see Ref. 1. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 320–324, February, 1998.     

Synthesis and structure of an arylpyran normal, pseudodiacid showing recognition

Abstract  

Oxidation of 1,4-bis(4′-oxo-2′,2′-dimethylpent-2-yl)benzene with hypochlorite produces 1,4-bis(3′-carboxy-2′-methylbut-2-yl)benzene and 3-(4′-carboxyphenyl)-3,3-dimethylpropanoic acid. Cyclization of this mixture forms 3,3,7,7-tetramethyl-1,2,3,5,6,7-hexahydro-s-indacen-1,5-dione, 3,3,7,7-tetramethyl-1,2,3,5,6,7-hexahydro-as-indacen-1,5-dione (5) and 6-carboxy-3,3-dimethyl-1-indanone (6). Ketoacid (6) is converted to the arylpyran pseudoacid 7-carboxy-3-hydroxy-4,4-dimethylisobenzopyran-1-one (7). In the crystal structure of (7), carboxylic acid and the pseudoacid groups each form complementary dimer hydrogen bonds linking the molecules in chains. Contact O···O distances reflect their differing energetics, with pseudoacyl O···O at 2.78(1)Å and carboxylic O···O at 2.62(1)Å.     

The effect of the physical state on the equilibrium conformation of 2-arylpyrroles

The equilibrium torsion angles of 2-arylpyrroles in the liquid and solid phases were estimated by UV spectroscopy. In solution, compounds containing no substituents in positions 1, 3, and 2′ possess an average torsion angle of 24°, those containing one substituent have an angle of 29°, and in the case of two and three substituents, the angles are 53° and 65°, respectively. Phase transitions lead to flattening of the molecules in almost all cases. The average torsion angles in the compounds with no substituents in positions 1, 3, and 2′ decrease by ≈5° on passing from the gas to the liquid state and by ≈25° on going from the liquid to the solid state. The geometric parameters of 2-arylpyrroles with one or two substituents in positions 1, 3, and 2′ are less sensitive to phase transitions, while trisubstituted derivatives even retain their equilibrium conformations upon phase transitions. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1472–1479, August, 1997.     

Molecular and crystal structures of stereoisomeric2R,3R,6S-2-(1′S-hydroxy-1′-biphenylyl)- and2R,3R,6S-2-(1′R-hydroxy-1′-biphenylyl)methyl-3-methyl-6-isopropylcyclohexanones

It was established by X-ray diffraction analysis that 2-(1′-hydroxy-1′-biphenylyl)methyl-3-methyl-6-isopropylcyclohexanone, one of the minor products of the directed aldol reaction of (−)-menthone bromomagnesium enolate with 4-phenylbenzaldehyde, has the2R,3R,6S, 1′R configuration. The characteristic features of the spatial structure of this β-hydroxyketone were compared with those of the major stereoisomeric product of the above-mentioned reaction. The latter has the2R,3R,6S,1′S configuration. In the crystals, both stereoisomers have the cyclohexanone ring in a chair-like conformation with the three substituents in equatorial positions and are characterized by the presence of the annelated (cis-fused) pseudoring with an −OH…O=C< intramolecular hydrogen bond. The structures of the stereoisomers differ in the orientation of the aryl group and the hydrogen atom at the C(1′) chiral center with respect to the cyclohexanone ring. The results of X-ray diffraction analysis were compared with the data of molecular mechanics calculation for the energetically most favorable conformations of the isolated molecules of β-hydroxyketones under study. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2251–2257, November, 1998.     

Interaction of water-soluble bridged porphyrin with DNA

A water-soluble porphyrin dimer (Por Dimer) containing eight positive charges, bridged by 4,4′-dicarboxy-2,2′-bipyridine, has been synthesized. With Meso-tetrakis(N-methyl-pyridium-4-yl)porphyrin (H₂TMPyP) as the reference compound, the water-soluble porphyrin dimer was investigated for its interaction with DNA by absorption, fluorescence, and circular dichroism (CD) spectroscopy. The apparent affinity binding constant (K _app = 1.2 × 10⁶) of Por Dimer binding to CT DNA was measured by a competition method with ethidium bromide (EB) (that of H₂TMPyP was 6.9 × 10⁶). The cleavage ability of Por Dimer to pBR322 plasmid DNA was studied by gel electrophoresis. The results suggest that the binding modes of Por Dimer were complex and involve both intercalation and outside binding. __________ Translated from Acta Chimica Sinica, 2007, 65(22): 2597–2603     

A spiral-like chain from a hydrogen-bonded cyclic dichloride containing a water dimer in a quaternary diammonium dichloride trihydrate

The reaction of benzyl chloride with tetramethylethylenediamine (tmen) results in the formation of the quaternary diammonium dichloride trihydrate (dbtmen)Cl₂·3H₂O 1 (dbtmen is N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium) in good yields. 1 crystallises in the monoclinic P2₁/c space group and its structure consists of N,N′-dibenzyl-N,N,N′,N′-tetramethylethylenediammonium dication, two chloride anions and three crystal water molecules all of which are located in general positions. The organic dication is H-bonded to the chloride anions and the crystal waters with the help of intra-and intermolecular C-H···Cl and C-H···O interactions, while the chloride anions are linked to the crystal waters via O-H···Cl interactions. One of the crystal waters is linked through an intermolecular O-H···O bond with another water resulting in the formation of a water dimer. The O-H···Cl and O-H···O interactions between the chloride anions and water molecules lead to the formation of a five-membered {O₃Cl₂} cyclic dichloride containing a water dimer. The five-membered rings are linked into a chain with the aid of a O-H···Cl interaction. The organic cations are organised in zigzag fashion on either side of the chain and are further linked to the anionic water chain via weak C-H···O and C-H···Cl interactions, leading to the supramolecular organisation of the rings into a spiral-like of chain. Dedicated to Prof. Sabyasachi Sarkar on the occasion of his 60^th birthday     

A cyclopendant complexon based on dibenzo-18-crown-6

A derivative of dibenzo-18-crown-6 containing dihydroxyphosphorylmethyl groups in the 4, 5, 4′, and 5′ positions of the benzene ring has been synthesized. Unlike dibenzo-18-crown-6, its phosphorylated derivative does not form stable complexes with cations of alkali and alkaline-earth metals. Complexes with transition metals are water-insoluble in most cases. Deceased. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1789–1791. September, 1998.     

New terpenoid coumarins from Ferula tadshikorum

Two new terpenoid coumarins — tadzhiferin (I) and tadzhikorin (II) — have been isolated from the fruit ofFerula tadshikorum M. Pimen. On the basis of physicochemical and spectral investigations, the structure of 7-(9′-hydroxy-3′,7′,11′-trimethyldodeca-2′,6′,10′-trienyloxy)coumarin is proposed for (I) and that of 7-(4′-acetoxy-9′-hydroxy-3′,7′,11′-trimethyldodeca-2′,6′,10′-trienyloxy)coumarin for (II).     

Metallophthalocyanines with rod-shaped substituents

4-(4′-Dioctylaminocarbonylbiphenyloxy) phthalonitrile was synthesized from 4-(4′-carboxybiphenyloxy)phthalonitrile and dioctylamine in the presence of Et₃N. Metallophthalocyanines (Zn, Co and Cu) substituted with four dioctylaminocarbonyl biphenyloxy groups on the peripheral positions were prepared from 4-(4′-dioctylaminocarbonylbiphenyloxy)phthalonitrile and the corresponding divalent metal salts (Zn(CH₃COO)₂, CoCl₂ and CuCl₂). The new phthalocyanines are soluble in common organic solvents. These compounds were characterised by ¹H-NMR, ¹³C-NMR, FT-IR, UV-Vis and mass spectroscopies.     

Investigations on 2,3′-Biquinolyl. 16. The Regioselectivity of Reduction of 1-Alkyl-3-(2-quinolyl)quinolinium and 1,1′-Dialkyl-3,3′-di(2-quinolyl)-1,1′,4,4′-biquinolyl Iodides Using Metallic Zinc,Lithium and Potassium

The reaction of 1-alkyl-3-(2-quinolyl)quinolinium iodides with excess zinc in THF gives a diastereomeric mixture of 1,1′-dialkyl-3,3′-di(2-quinolyl)-1,1′,4,4′-tetrahydro-4,4′-biquinolyls. An excess of lithium in THF gives a mixture of 1′,2′-dihydro-2,3′-biquinolyl and 1′-alkyl-1′, 4′-dihydro-2,3′-biquinolyl with the former predominating. The reduction by lithium in THF of 1,1′-dialkyl-3,3′-di(2-quinolyl)-1,1′,4,4′-tetrahydro-4,4′-biquinolyls leads to analogous products. Reduction of 1-alkyl-3-(2-quinolyl)quinolinium iodides by metallic potassium gives 1-alkyl-1′,4′-dihydro-2,3′-biquinolyls. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1208–1212, August, 2005.     

Photochromic dihetarylethenes

A series of new photochromic compounds were obtained for the first time from 1,2-bis(2-ethylthio-3-thienyl)perfluorocyclopentene by substituting bromine atoms or carboxy, alkoxycarbonyl, and carbamoyl groups for hydrogen atoms in positions 4 and 4′. Introduction of these substituents causes a slight bathochromic shift (by 20–30 nm) of a long-wavelength absorption band for the cyclic form and significantly increases the quantum yields of photocyclization Ф_A→B and ring opening Ф_B→A. Depending on the nature of a substituent, Ф_A→B decreases in the order COOH>COOMe>CONHAr. The quantum yields are markedly reduced when the ethylthio groups in positions 5 and 5′ are replaced by ethylsulfonyl groups (a tenfold reduction in Ф_A→B and a four- to fivefold reduction in Ф_B→A) The most considerable bathochromic shift of a long-wavelength band and the highest quantum yields of forward and reverse photoreactions were observed for 1,2-bis(4-bromo-2-ethylthio-3-thienyl) perfluorocyclopentene. 1,2- Bis (2-ethyl-5-ethylthio-4-methoxycarbonyl-3-thienyl)perfluorocyclopentene was structurally characterized by X-ray diffraction analysis.     

Thermal and environmental effects on Oligothiophene low-energy singlet electronic excitations in dilute solution: a theoretical and experimental study

The absorption spectra in dilute dichloromethane solution at 300 K of four Oligotiophenes (OT), namely 2,2′:5′,2″-Terthiophene, 2,2′:5′,2″:5″,2″′-Quaterthiophene, 4,4″′-Didodecyl-2,2′:5′,2″:5″,2″′-quaterthiophene and 5,5′′′′′-Dihexyl-2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′:5′′′′,2′′′′′-sexithiophene, have been studied both experimentally and theoretically by using a combination of molecular dynamics simulations, time-dependent density functional theory (TD-DFT) and perturbed matrix method calculations. A deep analysis of the theoretical results, affected by a systematic although not dramatic underestimation of the absorption maxima due to the well-documented TD-DFT limitations, clearly indicates that both the environmental (solvent) and thermal effects significantly alter the Oligotiophenes photophysical properties mainly because of the wide repertoire of the S₀–S₁ energy gaps and electronic densities experienced in solution by the different conformers actually populated. In particular, all the investigated OT display a very high flexibility resulting in a very high repertoire of sampled conformations. The comparison of the calculated and experimental lineshape of the S₀–S₁ electronic transition has clearly indicated that for a correct modeling of OT spectral features, the lack of an exhaustive sampling of semiclassical configurational space of the overall system, i.e., solute in interaction with the solvent, might result in an incomplete picture even in the presence of well-documented important aspects such as reliable definition of excited electronic states and the inclusion of quantum vibronic effects.     

Theoretical study of the structure and stability of cage-substituted icosahedral closo-boranes, alanes, and gallanes MiM′12 ? iH 122? (M, M′ = B, Al, and Ga; i = 0–12)

The equilibrium geometric parameters and energetic and spectroscopic characteristics of low-lying conformers for several series of model cage-substituted (mixed) borane, alane, and gallane closo-dianions M _i M′_{12 − i} H₁₂²⁻(M, M′ = B, Al, Ga), as well as of “bare” gallium-aluminum anions Ga _i Al_12−i ⁻ with i = 0–12, were calculated within the B3LYP approximation of the density functional theory using 6–31G* and 6–311+G** basis sets. Differences in structure and stability between alanoborane clusters of similar composition are revealed. In clusters where the M and M’ heteroatoms are close in size and electronegativity (in gallonoalanes and gallium-aluminum anions), successive substitutions of M′ for M are accompanied by small energy changes and occur quasi-stochastically in different positions of the cage. When the substituents are significantly different (in alanoboranes), mixed clusters are unstable against disproportionation into homonuclear “predecessors” M₁₂H₁₂²⁻ and M′₁₂H₁₂²⁻, and the most favorable M _i M′_{12 − i} H₁₂²⁻ structures among them are those in which M _i M′_{12 − i} the cages are subdivided into homonuclear “subclusters” M _i and M′t′_12−i with a maximal number of homonuclear bonds (M-M and M′-M′) and a minimal number of heteronuclear bonds (M-M′).     

Electrochromic properties of poly(alkoxy-terthiophenes): an experimental and theoretical investigation

Much effort has been made to synthesize novel compounds and enhance the optical properties of poly(terthiophenes). The electrochromic properties of poly(4,4′′-dimetoxy-3′-methyl-2′-5′,2′′-terthiophene) (PDMMT) and poly(4,4′′-dipentoxy-3′-methyl-2′-5′,2′′-terthiophene) (PDPMT) have been studied focusing on the differences in the alkoxy-group length. Theoretical calculations were employed to elucidate the structural and thermodynamic stability of the monomers and dimmers. The results showed that in this type of thiophenes large alkoxy chains assist positive charge dispersion through hyperconjugative effect. Thus, PDPMT is thermodynamically more stable than PDMMT in the oxidized state, leading to better electrochromic stability and optical memory.     

5-Diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles in [3+2] cycloaddition reactions

The [3+2] cycloaddition reactions of a series of 1,3-substituted 5-diazo-6,6-dimethyl-4-oxo-4,5,6,7-tetrahydroindazoles with maleic anhydride and dimethyl acetylenedicarboxylate gave 1′,3′-substituted 3-spiro[4,6-dioxo-4,6,3a,6a-tetrahydro-3H-furo[3,4-c]pyrazole]-5′-[6′,6′-dimethyl-4′-oxo-4′,5′,6′,7′-tetrahydroindazoles] and 1′,3′-substituted 3-spiro[4,5-di(methoxycarbonyl)-3H-pyrazole]-5′-[6′,6′-dimethyl-4′-oxo-4′,5′,6′,7′-tetrahydroindazoles] respectively. When heated the former eliminate nitrogen and are transformed into 1′,3′-substituted 6-spiro[2,4-dioxo-3-oxabicyclo[3.1.0]hexane]-5′-[6′,6′-dimethyl-4′-oxo-4′,5′,6′,7′-tetrahydroindazoles]. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1784–1791, December, 2007.