No abstract

We successfully performed the reduction of CO2 to CO by selective illumination of red visible light to a chlorophyll derivative covalently linked with a rhenium bipyridine complex. This is the first example of the photochemical reduction of CO2 using a sensitizer that has strong absorption at a wavelength over 650 nm.

We successfully developed selective synthesis of strongly emissive ring-shaped Re(I) multinuclear complexes (RnP(x)(n+) in Chart 1) with much higher yields compared with the previously reported method. This improved method could also be employed to prepare a novel ring-shaped multinuclear complex composed of structurally different Re(I) units. Each Re unit in RnP(x)(n+) could electrochemically accept one electron, and the multielectron reduced states of RnP(x)(n+) were stable. In the presence of triethanolamine, the ring-shaped tetranuclear and hexanuclear complexes can be photochemically reduced and accumulate 2.9-3.6 and 4.4 electrons in one molecule, respectively.

Abstract:The selective synthesis of 3,3-diarylacrylonitriles has been achieved by copper-catalyzed hydroarylation of 3-aryl-2-propynenitriles with arylboronic acids. The starting cyanoalkynes were efficiently prepared from the appropriate aromatic aldehydes and diethyl cyanomethylphosphonate in two steps. The hydroarylation of the obtained cyanoalkyne substrates proceeded in methanol at ambient temperature to produce 3,3-diarylacrylonitriles in good to high yields with excellent syn selectivity. The present method was successfully applied to the regiospecific synthesis of both stereoisomers of CC-5079, which was recently reported as a potent anticancer drug.

We investigated the excited state of a ring-shapeddinuclear Re(I) diimine bis-carbonyl complex that shows promise with regard to efficient photosensitized reactions and multi-electron storage,using time-resolved infrared(TR-IR) vibrational spectroscopy and quantum chemical calculations. Anomalouspeaks in the CO stretching region of the TR-IR spectrum werewell reproduced by the calculations. It was found that metal-to-ligand charge transfer occurs only in one of the Re complex units, andthat the excited state geometry is deformed relative to the ground state in order to relax the associatedsteric tension.Thisstructural deformationgenerates the unique photophysical properties of the complex.