利用STM探討Ru(bpy)2(phen-dione)2+與亞硼酸的電化學環合反應

Abstract

本研究合成系列釕金屬錯合物Ru(bpy)x(phen-dione)3-x2+ (x: 2, 3)，再利用掃瞄穿隧顯微術(STM)探討其與3-氨基苯亞硼酸(APBA)在碳質表面上進行化學反應時的影像變化。實驗結果顯示APBA可經由化學與電化學進行去氮反應，吸附於石墨烯(HOPG)表面。若再對該HOPG施加負電壓，則Ru(bpy)2(phen-dione)2+可與所吸附的APBA進行環合反應，形成奈米薄膜。對於所吸附的Ru(bpy)2(phen-dione)2+，原子力顯微術(AFM)顯示其膜厚度約為13 Å。由於Ru(bpy)2(phen-dione)2+的分子大小約為13.7 Å，我們據此推測該Ru(bpy)2(phen-dione)2+薄膜係以單層吸附方式吸附於石墨烯表面。此外，我們也藉由化學還原修飾法，將APBA與Ru(bpy)2(phen-dione)2+修飾於多壁奈米碳管(MWCNT)表面。當釕金屬錯合物修飾於奈米碳管(簡稱Ru@CNT)後，我們發現其具有光磁轉換性質。若將Ru@CNT置於水面，再以波長473 nm的雷射光進行照射，該碳管會被磁場排斥，朝與磁場相反方向移動。根據這些實驗結果，我們認為Ru@CNT在常溫常壓下具有光磁轉換的性質與應用潛力。

A series of ruthenium complexes of 1,10-phenanthroline-5,6-dione (denoted phen-dione) and 2,2’-bipyridine (denoted bpy) were synthesized and subjected to STM studies for their reactions with 3-aminophenylboronic acid (APBA) on carbon surfaces. Experimental results showed that when Ru(bpy)x(phen-dione)3-x2+ (x: 2, 3) complexes were brought into contact with APBA that was pre-covalently grafted to highly ordered pyrolytic graphite (HOPG) electrodes through chemical diazotization and electrochemical denitrogenation processes, the ruthenium complexes could be immobilized and therefore formed nanoscale films on the electrodes as the electrodes were biased with negative voltages. The thickness of the ruthenium layers was determined to be around 13 Å. According to the molecular size of the ruthenium complexes (~13.7 Å), we hypothesized that the ruthenium complexes formed monolayer deposition on the APBA-modified electrodes. We also monitored the reactions on multiwalled carbon nanotubes (MWCNT) by depositing APBA and ruthenium complexes on the tubes through chemical reduction processes. The resulting tubes (denoted Ru@CNT) showed photomagnetic signals, rendering them able to migrate oppositely towards external magnets as floating on water under the illumination of a 473-nm laser. These results showed that the synthesized carbon nanotubes could be useful in photomagnetic applications at ambient conditions.