A pellet of polycrystalline CuGaO 2 with a delafossite structure was prepared from Ga 2 O 3 and CuO by hightemperature solid-state synthesis. The CuGaO 2 pellet was a p-type semiconductor for which the electrical conductivity, carrier density, carrier mobility and Seebeck coefficient were 5.34 × 10 s −1 at room temperature, and +360 µV/K, respectively. It also exhibited two optical transitions at about 2.7 and 3.6 eV. The photoelectrochemical properties of the CuGaO 2 pellet electrode were investigated in aqueous electrolyte solutions. The flat-band potential of this electrode, determined using a MottSchottky plot, was +0.18 V vs SCE at pH 4.8 and followed the Nernst equation with respect to pH. Under UV light illumination, a cathodic photocurrent developed, and molecular hydrogen simultaneously evolved on the surface of the electrode due to the direct reduction of water without deposition of any metal catalyst.

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Tetraazamacrocycles L1 and L2, first synthesized by Kang et al., which are two of the 16 possible diastereoisomers of L have long been used for the preparation of many interesting metal complexes. [1][2][3][4][5][6] Although the macrocycles L1 and L2 show similar coordination tendencies to metal ions and form corresponding metal complexes, the chemical and structural properties of metal complexes are greatly influenced by the stereochemistry of cyclohexane rings fused on the 14-membered tetraazamacrocycle. Thus, the axial coordination of solvent molecules to the2 The bicarbonate ligands axially coordinate to The resulting differences between the metal complexes formed with macrocycles L1 and L2 in the above examples have been just ascribed to the structural characteristics of the macrocycles L1 and L2. However, it has not been clearly understood what the factors influence to the chemical and structural properties of metal complexes, and explanation and discussions are insufficient to explain the differences between the metal complexes formed with macrocycles L1 and L2. Therefore, we have prepared and studied a silver(II) supramolecular polymer {[Ag(L1)] (NO 3 ) 2 ․2H 2 O} n (1) in order to get further insight into the metal chemistry of L1, where the high oxidation state of silver(II) is stabilized by the tetraazamacrocycle L1 and the axial nitrate ions are supported by the methylene protons of the macrocycle through C-H···O hydrogen bonds. The details of the synthesis, structure, spectroscopic and electrochemical properties of 1 are discussed in this report.

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