The reaction of meta- and para-bromomethylene-azobenzenes with 1-methyl-imidazole yields the respective meta-/para-functionalized azobenzenes tagged with an imidazolium group. Similar reactions of ortho- and para-bromo-azobenzene with imidazole and successive quaternation with benzylbromide give the analogues, with an imidazolium group in ortho/para substituted azobenzenes. With the exception of the ortho derivative, all imidazolium salts could be transformed into their respective silver(i) complexes by reaction with Ag2O. Transmetallation of these silver(i) complexes with (Me2S)AuCl gives the azobenzene-containing complexes (NHC)AuCl. Two of these formed crystals suitable for X-ray diffraction, which revealed the typical linear coordination geometry of the NHC-Au-Cl moiety. All gold complexes feature E→Z photo-isomerisation upon irradiation with UV light. The thermal back reaction to the E-isomers is relatively slow and comparable to that of other azobenzene compounds.

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Applications for lignin and lignosulfonates are limited today due to the undefined structure and varying properties of the substance. However, lignin, as the second most abundant bio-resource besides cellulose and the bio-resource with one of the highest natural carbon contents, has the potential to act as a precursor for carbon materials. In this study we have applied a Kraft lignin and a sodium lignosulfonate with the cross-linker toluene-2,4-diisocyanate. The reaction mixture was molded to form small cylindrical shaped paddings. Cross-linked lignin-polyurethane and lignosulfonate-polyurethane networks were analyzed via elemental analysis and thermogravimetric analysis and finally carbonized. The carbon material was analyzed for its BET surface area and its surface structure via scanning electron microscopy. Surface areas between 70 and 80 m²•g −1 could be reached. Moreover, the material was tested for its adsorption potential of crude oil from water and could take up to twice its own weight. For better understanding of the core chemistry of the cross-linking reaction, we have studied the reaction with model substances to define the reactive groups and the influence of sulfonate groups in the cross-linking reaction of lignin and lignosulfonates with toluene-2,4-diisocyanate.

1-(2,2 -Diethoxyethyl)-3-methyl-imidazolium bromide, 1, has been prepared and used as a precursor for the synthesis of the corresponding silver bromide complex [(NHC) 2 Ag][AgBr 2 ], 2. Transmetallation of 2 with (tht)AuBr (tht = tetrahydrothiophene) yields (NHC)AuBr, 3. The solid-state structures of 2 and 3 have been determined by single-crystal X-ray diffraction revealing a loose aggregation of the complexes by weak metal-metal interactions. Due to the presence of these contacts, both complexes are emissive in the solid state.

In the crystal structure of the title compound, [Ag3Cl(C8H15N3)6]Cl2, the AgI ion, which is located on a twofold rotation axis, exists in a T-shape coordination environment. Two carbene C atoms of the N-heterocyclic carbene (NHC) ligands are bonded tightly forming a slightly bent [Ag(NHC)2]+ cation [C—Ag—C angle = 162.80 (18)°]. Three of these complex cations are further aggregated by one bridging chloride anion, which is lying on a threefold rotoinversion axis and is only loosely binding to the Ag+ ions. The N atom of the amine group is not engaged in any coordinative bond.