Kazuya Kitagawa

Simple and Efficient TiCl4-Mediated Synthesis of Biaryls via Arylmagnesium Compounds

Abstract Oxidative self-coupling reactions of various arylmagnesium bromides with TiCl 4 affords the corresponding symmetric biaryls in moderate to good yields at 0°C or lower. Tributylmagnesate-induced halogen–magnesium exchange of aryl halides followed by the coupling reaction provides biaryls in good yields under mild conditions. This method can achieve a one-pot synthesis of biaryls containing functional groups such as esters, amides, or nitriles.

Electronic Properties of Helical Peptide Derivatives at a Single Molecular Level

Electron transfer in helical peptide systems which were self-assembled on gold is described in this chapter. Electron transfer mechanism for the long distance through helical peptides is explained by the electron hopping between amide bonds. When naphthyl groups were linearly arranged along the helix scaffold, the electron hopping between naphthyl groups via anion radical was also observed. The aromatic linker between gold and the peptide accelerated electron transfer in the molecular system, and an intervening redox species in the helix also promoted electron transfer. The effects of helix dipole moment on electron transfer are also discussed.

Generation of a strong dipole layer and its function by using helical peptide molecular assemblies

Publisher Summary Generation of a Strong Dipole Layer and Its Function by Using Helical Peptide Molecular Molecular assemblies of helical peptides have been investigated since the 1950s. For example, poly(γ-methyl L-glutamate) was spread on water, and the π–A isotherm was measured. It was found that helix axes in the monolayer lay flat on the water surface. Upon compression, change from monolayer to bilayer was observed. These phenomena are commonly observed with other helical peptides, and it is a general understanding that it is a hard task to obtain helical peptide layers with a vertical orientation. In this chapter, the several factors that influence the orientation of helical peptides at an interface are introduced. A surface potential of a few hundred millivolts was generated by helical peptide SAMs having a few nanometer thickness. The electric field therefore, amounts to more than 106 V/cm. Because of the large electric field, the electron transfer through the helical peptide SAM is accelerated or hindered depending on the direction of the electron transfer for or against the electric field in the case of photocurrent generation using the helical peptide SAM in aqueous solution.