A New Supramolecular Tetraruthenated Cobalt (II) Porphyrazine Displaying Outstanding Electrocatalytical Performance in Oxygen Evolution Reaction

A new supramolecular electrocatalyst for Oxygen Evolution Reaction (OER) was synthesized from a central multibridging cobalt tetrapyridylporphyrazine (CoTPyPz) species by attaching four [Ru(bpy)₂Cl]⁺ groups. Both CoTPyPz and the tetraruthenated cobalt porphyrazine species, TRuCoTPyPz, form very homogenous molecular films just by dropcasting their methanol solutions onto GCE electrodes. Such films exhibited low overpotentials for O₂ evolution, e.g., 560 e 340 mV, respectively, displaying high stability, typically exceeding 15 h. The kinetic parameters obtained from the Tafel plots showed that the peripheral complexes are very important for the electrocatalytic activity. Hyperspectral Raman images taken along the electrochemical process demonstrated that the cobalt center is the primary active catalyst site, but its performance is enhanced by the ruthenium complexes, which act as electron-donating groups, in the supramolecular system.     

Formation of 1,3-dienetricarbonyliron complexes from the reaction of dipotassium tetracarbonylferrate with allylic compounds

The reaction of dipotassium tetracarbonylferrate with various allylic phosphates and halides gives 1,3-dienetricarbonyliron complexes. The formation of the complexes is highly stereoselective depending on the geometry of the allylic compounds used.     

Electrophilic substitution reaction of meso-ionic sesquifulvalene

The aromatic character of the meso-ionic sesquifulvalene (2) is demonstrated by six electrophilic substitution reactions on the cyclopentadienide ring.     

Samarium(II)-induced coupling of acid chlorides with allylic halides

Samarium(II)-induced coupling of acid chlorides with allylic halides gave diallylated tertiary alcohols. Monoallylated allylic ketones could not be obtained.     

Gallium-induced Barbier coupling of carbonyl compounds with allyl iodide

Gallium metal readily prompted the allylation of aldehydes and ketones with allyl iodide. α, β-Unsaturated carbonyl compounds underwent only 1,2-addition.     

Linkage isomerism,kinetics and electrochemistry of ruthenium-edta complexes of benzotriazole

The [RuIII(edta)(benzotriazole)]− complex has been investigated in aqueous solution, by means of cyclic voltammetry, stopped-flow kinetics and spectroelectrochemistry. The formation reaction, starting from [RuIII(edta)H2O]− and benzotriazole, leads essentially to the N(1) coordinated isomer. In the case of the RuII species, the products exhibit an intramolecular isomerization equilibrium involving the N(1) and N(2) binding sites, with K12=0.33. A complete set of acid/base and association constants has been obtained for the RuII and RuIII complexes. The data are coherent with theoretical calculations, reflecting the importance of π-backbonding interactions in the reduced species. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis of C4-linked imidazole ribonucleoside phosphoramidite with pivaloyloxymethyl (POM) group

A novel C4-linked imidazole ribonucleoside phosphoramidite was designed and successfully synthesized starting from tribenzylribofuranosylimidazole. This phosphoramidite product enables incorporation of the imidazole moiety into an RNA sequence and hence allows study of its role in the general acid and base catalysis of ribozymes. Pivaloyloxymethyl (POM) was first introduced as an N-protecting group for the imidazole ribonucleoside that can be readily removed under mild basic condition.     

On an inequality of Lieb and Thirring

The following generalization of an inequality of Lieb and Thirring is proved: