Photochemically induced formation of adhesive hydrogels from sodium alginate, acrylamide, and iron sandwich complexes.

Visible light irradiation of an aqueous solution of sodium alginate and organometallic complex [(C5H5)Fe(toluene)]BF4 transforms it into a rigid hydrogel due to crosslinking of the carboxylate groups by the iron ions. Irradiation of the same iron complex together with K2S2O8 initiates the polymerization of acrylamide, which provides an efficient method for light-controlled one-step preparation of alginate-polyacrylamide double network hydrogels, which are capable of gluing wet glass with 100-200 kPa shear strength.

Catalytic utilization of converter gas - an industrial waste for the synthesis of pharmaceuticals.

Converter gas is a large scale waste product that is usually burned to carbon dioxide and contributes to the world emission of greenhouse gases. Herein we demonstrate that instead of burning the converter gas can be used as a reducing agent in organic reactions to produce valuable pharmaceuticals and agrochemicals. In particular, amide-based selected drug molecules have been synthesized by a reaction of aromatic nitro compounds and carboxylic acids in the presence of converter gas. In addition, we showed that this gas can also be conveniently utilized to carryout classical reductive amination reaction.

Synthesis and reactivity of cyclobutadiene nickel bromide.

NiBr2 reacts with 3-hexyne in the presence of Mg and EtOH to give the cyclobutadiene bromide complex [(C4Et4)NiBr2]2, which serves as a general precursor for various cyclobutadiene nickel compounds. In particular, complexes with 2-electron ligands (C4Et4)Ni(L)Br2 (L = PPh3, P(OMe)3, pyridine), complexes with bidentate ligands [(C4Et4)Ni(L2)Br]PF6 (L2 = bipyridine, phenanthroline), and nickelacarborane (C4Et4)NiC2B9H11 were obtained from [(C4Et4)NiBr2]2 in 70-95% yields. The reactions of [(C4Et4)NiBr2]2 with an excess of strong ligands, such as tBuNC or dppe, led to the displacement of cyclobutadiene. The structures of the five compounds have been established by X-ray diffraction analysis. The previously reported data on cyclobutadiene nickel complexes have been also reviewed.

Aldehydes as Alkylating Agents for Ketones.

Common and non-toxic aldehydes are proposed as reagents for alkylation of ketones instead of carcinogenic alkyl halides. The developed reductive alkylation reaction proceeds in the presence of the commercially available ruthenium catalyst [(cymene)RuCl2 ]2 (as low as 250 ppm) and carbon monoxide as the reducing agent. The reaction works well for a broad substrate scope, including aromatic and aliphatic aldehydes and ketones. It can be carried out without a solvent and often gives nearly quantitative yields of the products. This straightforward and cost-effective method is promising not only for laboratory application but also for industry, which produces carbon monoxide as a large-scale waste product.

Selective ruthenium labeling of the tryptophan residue in the bee venom Peptide melittin.

Melittin is a membrane-active peptide from bee venom with promising antimicrobial and anticancer activity. Herein we report on a simple and selective method for labeling of the tryptophan residue in melittin by the organometallic fragment [(C5 H5 )Ru](+) in aqueous solution and in air. Ruthenium coordination does not disturb the secondary structure of the peptide (as verified by 2D NMR spectroscopy), but changes the pattern of its intermolecular interactions resulting in an 11-fold decrease of hemolytic activity. The high stability of the organometallic conjugate allowed the establishment of the biodistribution of the labeled melittin in mice by inductively coupled plasma MS analysis of ruthenium.

Simple synthesis of ruthenium pi complexes of aromatic amino acids and small peptides.

The interaction of [Ru(eta(6)-C(10)H(8))(Cp)](+) (Cp=C(5)H(5)) with aromatic amino acids (L-phenylalanine, L-tyrosine, L-tryptophane, D-phenylglycine, and L-threo-3-phenylserine) under visible-light irradiation gives the corresponding [Ru(eta(6)-amino acid)(Cp)](+) complexes in near-quantitative yield. The reaction proceeds in air at room temperature in water and tolerates the presence of non-aromatic amino acids (except those which are sulfur containing), monosaccharides, and nucleotides. The complex [Ru(eta(6)-C(10)H(8))(Cp)](+) was also used for selective labeling of Tyr and Phe residues of small peptides, namely, angiotensin I and II derivatives.