We report the synthesis, film formation, protein resistance, and specific antigen binding capability of a carboxy-functionalized poly(ethylene glycol) alkanethiol [HOOC-CH2-(OCH2-CH2)n-O-(CH2)11-SH, n ) 22-45]. Despite its polymeric character, the molecule is found to form a densely packed self-assembled monolayer on polycrystalline gold, if adsorbed from dimethylformamide solution. Due to its chain length distribution, the carboxy tailgroups are expected to be partially buried within the film and, thus, do not affect the protein repulsive characteristics of the ethylene glycol moieties when exposed to fibrinogen and immunoglobulin G (IgG). However, if activated by N-hydroxysuccinimide and N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, antibodies can be covalently coupled to the monolayer. While resistance to nonspecific fibrinogen and IgG adsorption is maintained for this biologically active layer, it exhibits high specific antigen binding capacity. The performance of this highly selective surface is compared to that of antibody films prepared by standard aminosilane chemistry.

The effects of the ligand to metal ratio, temperature, syngas pressure, partial pressures of H2 and CO, and new ligand structures have been examined on 12 of the most reasonable products resulting from the rhodium-catalyzed low-pressure hydroformylation of 1,3-butadiene. The selectivity for the desired linear dihydroformylation product, 1,6-hexanedial (adipic aldehyde), is essentially independent of all of these reaction parameters, except for ligand structure. However, the reaction parameters do have a substantial effect on the selectivity for the products, resulting from the branched addition of the rhodium hydride to the carbon–carbon double bond. The optimum reaction parameters and ligand have resulted in a so far unprecedented maximum selectivity of 50% for adipic aldehyde.

The hydroformylation catalyst (L)RhH(CO) 2 , with a triptycene-derived bisphosphite ligand, and its iridium analogue were studied in solution, in the solid state, and computationally (DFT) in order to determine their molecular structures and to understand the equilibria between isomers. The predicted intramolecular distance of the two biphenyl side groups of these ligands strongly depends upon the treatment of inter-and intramolecular noncovalent interactions. A balanced treatment of these "weak" interactions is a prerequisite for obtaining reasonable structures and consequently also for determining relative energies of the different P-coordination modes. Low-temperature NMR studies confirm the equilibrium between axial−equatorial and equatorial−equatorial isomers in solution and have been used to estimate their relative stability in the equilibrium.

We report the synthesis and single-crystal molecular structures of two stereoisomers of trigonalbipyramidal hydrido dicarbonyl Ir complexes [(L 2 )Ir(H)-(CO) 2 ] with ae (axial−equatorial) and ee (equatorial− equatorial) ligand P coordination and fluxional behavior in solution. L 2 is a new chelating bisphosphite with unprecedented high selectivity in Rh-catalyzed bis-hydroformylation of butadiene to adipic aldehyde. These Ir analogues are ideal stabilized structural models for nonseparable ae and ee Rhhydroformylation resting state isomers [(L 2 )Rh(H)(CO) 2 ]. With Ir, both stereoisomers with the same ligand could be characterized independently for the first time.

Crotyl rhodium complexes like (κ2-L)­Rh(η3-crotyl) and (κ2-L)­Rh(η3-crotyl)­(CO) (L = chelating phosphorus ligand) are important intermediates in hydroformylation catalysis of butadiene and related reactions. They are assumed to be responsible for the specific reactivity patterns of conjugated dienes. We prepared and characterized by X-ray crystallography several of these complexes with novel chelating bisphosphite ligands. (κ2-L)­Rh(η3-crotyl) complexes exhibit a square-planar geometry, while their CO adducts (κ2-L)­Rh(η3-crotyl)­(CO) are trigonal-bipyramidal with the bisphosphite ligand in ee-bonding mode. Typically, the η3-crotyl unit can be oriented in several diastereomeric ways, of which oftentimes two or more are present in solution and in the solid state.