The solubility loop of nicotine:water

The lower consolute temperature in the nicotine:water system arises from the equilibrium formation of a covalent hydrate, revealed by its unique circular dichroism.     

Cosmic-ray electron flux measured by the PAMELA experiment between 1 and 625 GeV

Precision measurements of the electron component in the cosmic radiation provide important information about the origin and propagation of cosmic rays in the Galaxy. Here we present new results regarding negatively charged electrons between 1 and 625 GeV performed by the satellite-borne experiment PAMELA. This is the first time that cosmic-ray e? have been identified above 50 GeV. The electron spectrum can be described with a single power-law energy dependence with spectral index -3.18 ± 0.05 above the energy region influenced by the solar wind (> 30 GeV). No significant spectral features are observed and the data can be interpreted in terms of conventional diffusive propagation models. However, the data are also consistent with models including new cosmic-ray sources that could explain the rise in the positron fraction.     

Pyrrolo[2,1-c][1,4]benzodiazepines. Synthesis of new cyclic amidines and fused[a]triazolo,tetrazolo and oxadiazolo derivatives

We report the practical synthesis of new cyclic amidines from thiolactams and the preparation of fused[a]triazolo, tetrazolo and oxadiazolo derivatives via hydrazidines and oximes, in the pyrrolo[2,1-c]-[1,4]benzodiazepine series.     

Equilibria in complexes ofN-heterocyclic molecules,part X. The pH dependent racemization of tris-(1,10-phenanthroline)nickel(II)

Summary Circular dichroism and electronic spectral measurements have established the existence of a covalent hydrate and a pseudobase arising from attack of H₂O or HO^– at the ligand in tris-(1,10-phenanthroline)nickel(II). In anhydrous solvents and strongly acidic solution, the complex is largely unsolvated. Over a large pH range the dominant species present in aqueous solution is the covalent hydrate while at high pH, this is converted into the pseudo-base. The existence of these species, and the equilibria between them in aqueous solution elegantly explains the pH dependent dissociation and racemization of the parent molecule. It further explains the non-linear variation of these reactions in mixed solvents and indicates that more than one mechanism is responsible over the range of solvents studied here and previously.Part IX,Transition Met. Chem., 2, 12 (1977).This ready change was pointed out to one of us (R.D.G.) some years ago by Professor B. Bosnich.     

Reactions of complex compounds of cobalt,part XI. Mechanism of the oxidative degradation of coordinated salicylate

Summary Specifically labelled [1-¹³C ]salicylic acid has been made by a logical route involving the thermolysis of basic copper(II) benzoates, and the position of labelling established from the spin-spin coupling pattern of the product, p-hydroxybenzoic acid, of isomerisation. The results reinforce findings on the origin of the carbon atoms of chelated oxalate derived from chelated salicylate.Part X, see ref. 1.     

Metal complexes as indicators of solvent structures. Part IV. The effect of solvation on the interaction between tris-1,2-diaminoethanecobalt(III) and anions in aqueous solution

Summary Changes in the circular dichroism of (+)tris-1,2-diaminoethanecobalt(III) in the presence of sulphate ion can be attributed to changes in the cybotactic solvation of the complex ion as well as to the formation of discrete ion-pairs.Parts 1, 2 and 3: R. D. Gillard and H. M. Sutton,J. Chem. Soc., A, (1970) 1309, 2172 and 2175 respectively.     

Trimethylsilyl bromide as a mild,stereoselective anomeric brominating agent

Stereoselective bromination of anomeric glycosyl acetates was achieved with trimethylsilyl bromide under mild conditions and in the presence of various protecting groups commonly employed in carbohydrate chemistry.     

Chiroptical properties of streptonigrin and a comment on atropisomerism in heterocyclic compounds

Chiroptical properties of streptonigrin (from Streptomyces flocculus) and its monoxime are recorded. This is the first case of atropisomerism arising from a phenylpyridine in a natural product, and from any 4-phenylpyridine.