时间：6月22日（周六) 下午15:30
地点：化学楼二楼会议室
摘要：
Surface coordination network films have paid much attention because of their potential interests for various fields such as molecular devices and sensors, and also energy or charge storage devices. To construct the surface coordination network structures at the nanometer scale, a layer-by-layer (LbL) growth of functional complex units is one of the well-established methods. We have developed molecular electrochemical devices on an ITO electrode based on coordination network films composed of ruthenium complexes. The coordination network films were fabricated from redox-active Ru complex units (see Figure 1 for the chemical structures and their abbreviations) by use of LbL assembly between the Ru complex with phosphonate groups and zirconium(IV) ions.Scalable homo-layered LbL films were grown on the ITO electrode, in which the smaller dependence of the electron transfer (ET) rate on the film thickness was observed. The stepping-stone mechanism plays an important role for the ET events in the film. The homo-layer films of ITO|(Ru-NP)n have been applied for the electrochemical energy storage device. From the EQCM measurements on the charging-discharging process, a reversible mass change was demonstrated. On the other hand, in the case of ITO|(Ru-NH-P)n showing proton-coupled ET (PCET) reactions, little mass change was observed because of the charge compensation by proton release from the Ru-NH-P upon the Ru(II/III) oxidation. By introducing the cyclometallated bond, Ru-CH-P possessed lower oxidation potentials and higher pKa values compared to those for Ru-NH-P. By connecting these two electrodes from ITO|(Ru-NH-P)n and ITO|(Ru-CH-P)n, we fabricated a proton rocking-chair type redox capacitor in neutral aqueous solution. Hetero-layer junction composed of two Ru complex units with different redox potentials exhibited an electrochemical rectification on ITO|(Ru-NP)n/(Ru-CP)n (n>2). At the rectified condition, the charge trapping state was read out by the direction of photocurrent. Therefore, the present heterolayer films can be applied to the photo-responsive memory device.
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