Dehydrogenation of Formic Acid Catalyzed by a Ruthenium Complex with an N,N'-Diimine Ligand.

We report a ruthenium complex containing an N,N'-diimine ligand for the selective decomposition of formic acid to H2 and CO2 in water in the absence of any organic additives. A turnover frequency of 12 000 h-1 and a turnover number of 350 000 at 90 °C were achieved in the HCOOH/HCOONa aqueous solution. Efficient production of high-pressure H2 and CO2 (24.0 MPa (3480 psi)) was achieved through the decomposition of formic acid with no formation of CO. Mechanistic studies by NMR and DFT calculations indicate that there may be two competitive pathways for the key hydride transfer rate-determining step in the catalytic process.

Aluminium complexes of bidentate N,O- and N,N-ligands derived from oxidative functionalization of amido phosphines: synthesis, structure and reactivity.

A series of amido phosphinoxide and amido phosphinimine ligands that are electronic variations of monoanionic N,O- and N,N-ketiminates have been prepared and employed to examine the coordination chemistry of aluminium. Oxidation of the previously established N-(2-diphenylphosphinophenyl)-2,6-dialkylaniline in the presence of H(2)O(2) or organic azides RN(3) (R = 2,6-C(6)H(3)(i)Pr(2), SiMe(3)) led to phosphinoxides (H[NO] 1a-b) and phosphinimines (H[NN] 1c-d), respectively. Alkane elimination reactions of these protio-ligand precursors with trialkylaluminium in toluene or pentane solutions afforded cleanly the corresponding organoaluminium complexes, including dimethyl 2a-d, diethyl 3a-d and diisobutyl derivatives 4a-b and 4d. Solution NMR studies revealed Cs symmetry for these organoaluminium species, in which the α-hydrogen atoms are all diastereotopic. The correlation between the steric congestion of these molecules and the degree of resolution of the multiplet signals corresponding to the diastereotopic α-hydrogen atoms observed by the (1)H NMR spectroscopy is of particular interest. Dichloroaluminium complexes 5c-d were prepared in high yields by protonolysis of MeAlCl(2) with 1c-d. Single-crystal X-ray diffraction analyses of 2c-d, 3a, 3d, 4a, and 4d elucidated a mononuclear, distorted tetrahedral core for all of these aluminium species. Interestingly, complexes 2c-d are active initiators for catalytic ring-opening oligomerization of ε-caprolactone, whereas 2a-b are rather inactive, highlighting the significance of the steric hindrance imposed by the amido phosphinimine ligands, as compared to that imposed by the phosphinoxide counterparts.

Down-regulation of gp130 in nasopharyngeal carcinoma.

BACKGROUND: The purpose of this study was to explore the expression and biological functions of glycoprotein 130 (gp130) in Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC). A prospective study was performed. METHODS: Ten patients with NPC and 10 patients with nasopharyngeal lymphoid hyperplasia (LH) were enrolled in this study. The transcripts of IL-27 receptors (gp130 and WSX-1) in the biopsy specimens derived from NPC were compared with that from LH by using reverse-transcription polymerase chain reaction. Cell lines including EBV(-), Burkitt-like lymphoma (BJAB) cells, human adult peripheral blood mononuclear cells, and lymphoblastoid cell lines were used to provide evidence of the biological function of gp130. In addition, killing assay for natural killer (NK) cells was performed in the presence of gp130. RESULTS: There was significantly stronger expression of gp130 on the LH specimens than on the NPC specimens. The levels of gp130 mRNA were reduced in the EBV-transformed cells. The cytotoxicity ratio against gp130-deficient B cells was diminished compared with gp130-existent B cells. CONCLUSION: The expression of gp130 is down-regulated in patients with NPC. We presume that EBV controls the functions of NK cells through regulation of gp130 cytokine receptor.

Aluminum complexes incorporating bidentate amido phosphine ligands.

A series of aluminum complexes supported by o-phenylene-derived amido phosphine ligands, N-(2-diphenylphosphinophenyl)-2,6-dimethylanilide ([Me-NP]-) and N-(2-diphenylphosphinophenyl)-2,6-diisopropylanilide ([iPr-NP]-), have been prepared. The reactions of trialkylaluminum with H[Me-NP] and H[iPr-NP], respectively, in refluxing toluene produced the corresponding dialkyl complexes [Me-NP]AlR(2) and [iPr-NP]AlR(2) (R = Me, Et). Deprotonation of H[Me-NP] with n-BuLi in THF at -35 degrees C followed by addition of AlCl(3) in toluene at -35 degrees C afforded [Me-NP]AlCl(2), which was subsequently reacted with 2 equiv of trimethylsilylmethyllithium in toluene to give [Me-NP]Al(CH(2)SiMe(3))(2). The aluminum complexes were all characterized by (1)H, (13)C, (31)P, and (27)Al NMR spectroscopy. The solid-state structures of monomeric, four-coordinate [Me-NP]AlEt(2) and [iPr-NP]AlMe(2) and five-coordinate [Me-NP]AlCl(2)(THF) were determined by X-ray crystallography. The (1)H NMR studies of [Me-NP]AlEt(2), [Me-NP]Al(CH(2)SiMe(3))(2), and [iPr-NP]AlEt(2) indicate diastereotopic alpha-hydrogen atoms in these molecules. Heteronuclear COSY and NOE experiments suggest that the phosphorus donor in [Me-NP]Al(CH(2)SiMe(3))(2) and [iPr-NP]AlEt(2) is coupled to only one of the diastereotopic alpha-hydrogen atoms that is virtually antiperiplanar with respect to the phosphorus atom.