Synthesis of the isomeric monomethyl derivatives of the novel naphtho[2′,1′:4,5]thieno[2,3-c]quinoline ring system

The synthesis of the novel naphtho[2′,1′:4,5]thieno[2,3-c]quinoline (11) ring system and four of the isomeric monomethyl derivatives is described.     

Radical hydroformylation and hydrogenation of cyclopropenes with HCo(CO)4 and HMn(CO)5

The results of a study of the reactions of HCo(CO)₄ and HMn(CO)₅ with a variety of a substituted cyclopropenes are consistent with the formation of the intermediate caged radical pairs; recombination in the cage of the radical pair leads to hydroformylation, and cage escape leads to hydrogenation. Steric factors play an important role in determining rates as well as the stereochemistry of the products.     

Synergism in the spreading of hydrocarbon-chain surfactants on polyethylene film-anionic and cationic mixtures by a two-step procedure

A study has been made of the adsorption, interaction, and spreading of mixtures of anionic and cationic surfactants at the aqueous solution/polyethylene (PE) interface. When a drop of an aqueous solution of an anionic or cationic hydrocarbon-chain surfactant is placed on a highly hydrophobic PE film (contact angle of water > 90 degrees ), it spreads to an area very little larger than that of a drop of water of the same volume. If the anionic and cationic hydrocarbon-chain surfactant solutions are mixed prior to being applied to PE film, synergism is small, if any, and the reproducibility of the experimental results is poor. However, when the cationic and anionic aqueous solutions are applied on the PE film in a sequential manner, a remarkable synergism in spreading is observed and the results are very reproducible. The area spread by an aqueous solution of the anionic-cationic mixture may be more than 400 times that of aqueous solutions of the same volume and surfactant concentration of the individual surfactant components. Previous work in this laboratory on surfactant systems showing synergism in spreading on PE film, but only weak interaction at the aqueous solution/air interface, showed that the synergy was due to changes at the aqueous solution/PE interface and not to the changes at the aqueous solution/air or PE/air interface. Investigation of the adsorption behavior at the aqueous solution/solid interface of two of the anionic-cationic mixtures studied here indicates the reason for differences in spreading behavior observed with different anionic-cationic mixtures. The more similar the adsorption tendencies at the solid/aqueous solution interface of the anionic and cationic surfactants, and the closer their adsorption to an equimolar monolayer there, the stronger their interaction there and the greater their enhancement of the spreading. A mechanism is proposed for the synergy in spreading observed, based upon the difference between the surface tension in the precursor film at the spreading interface and that at the top of the spreading drop.     

Angular polycyclic thiophenes containing two thiophene rings. I

We describe the synthesis of thieno[2,3-c]dibenzothiophene ( 6 ), thieno[3,2-c]dibenzothiophene ( 10 ), thieno-[3,2-a]dibenzothiophene ( 14 ), thieno[2,3-a]dibenzothiophene ( 16 ), benzo[1,2-b:4,3-b]bisbenzo[b]thiophene ( 18 ), benzo[1,2--6:3,4-b]bisbenzo[b]thiophene ( 20 ), benzo[2,1--6:3,4-b]bisbenzo[b]thiophene ( 22 ), benzo[1,2-b:3,4-g]bisbenzo[b]thiophene ( 27 ), benzo[1,2-b:4,3-e]bisbenzo[b]thiophene ( 29 ), benzo[2,1--6:3,4-g]bisbenzo[b]thiophene ( 36 ), benzo[2,1--6:4,3-e]bisbenzo[b]thiophene ( 38 ), benzo[1,2--6:4,3-g]bisbenzo[b]thiophene ( 41 ), benzo[1,2-b:4,5-g]bisbenzo[b]thiophene ( 42 ), benzo[1,2-b:3,4-e]bisbenzo[b]thiophene ( 44 ) and benzo-[1,2-b:5,4-e]bisbenzo[b]thiophene ( 45 ).     

Benzannelated analogs of phenanthro[1,2-b]- and [2,1-b]thiophene: Synthesis and structural characterization by two-dimensional NMR and X-ray techniques

Syntheses of benzo[3,4]phenanthro[1,2-b]thiophene, benzo[3,4]phenanthro[2,1-b]thiophene and their 1-methyl analogs are reported as potential constituents of solvent refined coal liquids and for mutagenicity testing. The attempted synthesis of the 13-methyl analogs which gave the 11-methyl isomers is also described. Total assignments of the ¹H- and ¹³C-nmr spectra based on long range optimized heteronuclear protoncarbon two-dimensional chemical shift correlation are reported. Carbon assignments obtained for benzo[3,4]-phenanthro[1,2-b]thiophene using this approach were confirmed with a 125 MHz ¹³C–¹³C INADEQUATE spectrum. X-Ray crystal structures were determined for benzo[3,4]phenanthro[1,2-b]thiophene and 1-methyl-benzo[3,4]phenanthro[2,1-b]thiophene. Both molecules were helically distorted from planarity. Close intramolecular contacts between the bay region H1–H13 and ClMe-H13 of 2.03 and 2.28 Å, respectively, were responsible for the distortions. There were no close intermolecular contacts of <3.5Å. both molecules refined to an R value of <0.05.     

Synthesis of phenaleno[1,9-bc]thiophene

The cyclization of 2-acetonylthionaphthalene, prepared from 2-mercaptonaphthalene (1) and chloro-acetone in the presence of sodium hydroxide, with polyphosphoric acid gave 1-methylnaphtho[2,1-b]thiophene (4) in 64% overall yield from 1. By bromination with N-bromosuccinimide, 4 was converted in 40% yield into l-bromomethylnaphtho[2,1-b]thiophene (8) . Treatment of 8 with potassium cyanide in a phase-transfer medium gave l-cyanomethylnaphtho[2,1-b]thiophene (10) in good yield. Compound 10 was reduced to the corresponding aldehyde 11 and then cyclized with polyphosphoric acid to phenaleno[l,9-bc]thiophene (12) in 24% overall yield from 10.     

New pyridine carboxamide ligands and their complexation to copper(II). X-Ray crystal structures of mono-, di, tri- and tetranuclear copper complexes

Seven new pyridine dicarboxamide ligands H2L(1-7) have been synthesised from condensation reactions involving pyridine-2,6-dicarboxylic acid (H2dipic), pyridine-2,6-dicarbonyl dichloride or 2,6-diaminopyridine with heterocyclic amine or carboxylic acid precursors. Crystallographic analyses of N,N'-bis(2-pyridyl)pyridine-2,6-dicarboxamide monohydrate (H2L8 x H2O), N,N'-bis[2-(2-pyridyl)methyl]pyridine-2,6-dicarboxamide and N,N'-bis[2-(2-pyridyl)ethyl]pyridine-2,6-dicarboxamide monohydrate revealed extensive intramolecular hydrogen bonding interactions. 2,6-Bis(pyrazine-2-carboxamido)pyridine (H2L6) and 2,6-bis(pyridine-2-carboxamido)pyridine (H2L7) reacted with copper(II) acetate monohydrate to give tricopper(II) complexes [Cu3(L)2(mu2-OAc)2]. X-Ray crystallography confirmed deprotonation of the amidic nitrogen atoms and that the (L6,7)2- ligands and acetate anions hold three copper(II) ions in approximately linear fashion. H2L8. Reacted with copper(II) tetrakis(pyridine) perchlorate to give [Cu(L8)(OH2)]2 x 2H2O, in which (L8)2- was tridentate through the nitrogen atoms of the central pyridine ring and the deprotonated carboxamide groups at one copper centre, with one of the terminal pyridyl rings coordinating to the other copper atom in the dimer. The corresponding reaction using H2L7 gave [Cu3(L7)2(py)2][ClO4]2, which transformed during an attempted recrystallisation from ethanol under aerobic conditions to a tetracopper(II) complex [Cu4(L7)2(L7-O)2].     

Angular polycyclic thiophenes containing two thiophene rings. Part II

The syntheses of naphtho[1,2–6:7,6-b′]bisbenzo[b]thiophene ( 4 ), naphtho[1,2–6:7,8-b′]bisbenzo[b]thiophene ( 5 ), naphtho[2,1-b:7,6-b′]bisbenzo[b]thiophene ( 8 ), naphtho[2,1-b:7,8-b′]bisbenzo[b]thiophene ( 9 ), naphtho-[1,2–6:5,6-b′]bisbenzo[b]thiophene ( 14 ), naphtho[1,2–6:6,5-b]bisbenzo[b]thiophene ( 17 ) and naphtho[2,1–6:-6,5-b′]bisbenzo[b]thiophene ( 23 ) are reported.     

Binding behaviour and conformational properties of globular proteins in the presence of immobilised non-polar ligands used in reversed-phase liquid chromatography

The thermodynamic and extra-thermodynamic dependencies of five types of cytochrome c in water-acetonitrile mixtures of different composition in the presence of immobilised n-octyl ligands as a function of temperature from 278 K to 338 K have been investigated. The corresponding enthalpic, entropic and heat capacity parameters, deltaHdegrees assoc, deltaS degrees assoc and delta C degrees p, have been evaluated from the observed non-linear Van't Hoff plots of these globular proteins in these heterogeneous systems. The relationships between the free energy dependencies, various molecular parameters and extra-thermodynamic dependencies (empirical correlations) of these protein-non-polar ligand interactions have also been examined. Thus, the involvement of enthalpy-entropy compensation effects has been documented for the binding of these cytochrome cs to solvated n-octyl ligands. Moreover, the results confirm that this experimental approach permits changes in molecular surface area due to the unfolding of these proteins on association with non-polar ligands as a function of temperature to be correlated with other biophysical properties. This study thus provides a general procedure whereby the corresponding free energy dependencies of globular proteins on association with solvated non-polar ligands in heterogeneous two-phase systems can be quantitatively evaluated in terms of fundamental molecular parameters.     

The stoichiometric hydrogenation of 9-methylidenefluorene and related compounds with hydridocobalt tetracarbonyl

9-Methylideneflourene (IIa) reacts rapidly with HCo(CO)₄ at -67° C to give a quantitative yield of 9-methylfluorene (IIIa); k₂  (13.4 ± 0.5) × 10^-2 l mol^-1_S^-1. Although the internal olefin, 9-ethylidenefluorene (IIb) reacts more slowly than IIa, it is hydrogenated about 2.5 times as fast as the terminal olefin, 1,1-diphenylethylene (I). Measurement of the rate of the reaction of IIb with DCo(CO)₄ and comparison with HCo(CO)₄ shows a very large inverse isotope effect k_H/k_D of 0.43.