Synthesis, characterization and protonation reaction of copper and palladium complexes bearing nitrite ligands in O,O-bidentate and N-monodentate bonding fashions

Nitric oxide-release study of a bio-inspired copper(i)-nitrito complex under chemical and biological conditions

The selective and efficient nitrite reduction process is ubiquitous in biological systems. To understand copper-mediated nitrite reduction, we developed a bio-inspired model system to investigate the mechanism of copper-containing nitrite reductase. A well-characterized copper(i)-nitrate complex with amino functionalized 2-(diphenylphosphino)aniline ligands, [(Ph₂PC₆H₄(o-NH₂))₂Cu(ONO)], demonstrated the aniline protonation will cause NO release in an acidic environment. To further understand NO releasing ability, we also performed pH-dependency experiments and confocal imaging to release NO under physiological buffer conditions. According to titration and spectroscopic studies on the protonation reaction of complex [(Ph₂PC₆H₄(o-NH₂))₂Cu(ONO)], we proposed a mechanistic pathway for proton transfer and NO release. Furthermore, DFT calculations predicted that the release of NO takes place via aniline in both organic and aqueous media. These results highlight the importance of the proton-rich microenvironment around the copper(i)-nitrite core to induce nitrate reduction in a chemical and biological environment.

Suzuki coupling for preparation of allenes – ligand effects and chirality transfer

o-(Diphenylphosphino)benzaldehyde has been identified as the effective ligand for the coupling of propargylic carbonates and organoboronic acids under mild conditions.