利用掃描式電子穿隧顯微鏡研究苯胺分子與掌性有機酸於金電極之吸附結構與聚合行為

Electrochemical polymerization of aniline on Au(111) and Au(100) in camphor-sulfonic acid and tartaric acid

莊雅玲(Ya-ling Chuang)

指導教授 ： 姚學麟

國立中央大學/理學院/化學系/碩士(2011年)

摘要

利用掃描式電子顯微鏡(in situ scanning tunneling microscopy, STM)及循環伏安法(cyclic voltammetry, CV)，探討兩種具有對掌性質之有機酸：D-(+)-和L-(-)-樟腦磺酸及D-(-)-和L-(+)-酒石酸，在單晶電極金(111)、金(100)上，隨電位之結構變化，並且與苯胺分子進行氧化聚合反應，觀察其聚合前之單體吸附結構、聚合反應的過程，以及聚苯胺之構形比較。苯胺分子在D,L-樟腦磺酸溶液中，隨著電位之變化，於金(111)、金(100)分別觀察到不同的結構吸附層，苯胺受到酸根分子的影響，誘導苯胺鏈形成螺旋且以3D之方式成長。苯胺分子在D,L-酒石酸中，隨著電位之變化，受到酸根分子的影響，分別得到不同之結構，而苯胺鏈也相同受到酸根分子中的-OH官能基誘導形成螺旋構形，有趣的是苯胺分子在D-(-)-酒石酸系統中，其聚苯胺構形與L-(+)-酒石酸中不同，苯胺鏈在表面形成線性且沿著√10方向生長，隨著電位和時間之變化，形成類似螺旋之特殊構形。藉由具對掌性質之有機酸與苯胺進行掺雜，利用電化學方法觀察苯胺分子氧化聚合之過程，得到不同構形之聚苯胺鏈，期望日後進行光學活性之檢測，進而應用在對掌分子之分離與生物感測器之相關範疇。

關鍵字

掌性 ； 掃描式電子穿隧顯微鏡 ； 苯胺

並列摘要

In situ scanning tunneling microscopy (STM) and cyclic voltammetry (CV) have been used to explore the adsorption and electropolymerization of aniline on ordered Au(111) and Au(100) electrodes in 0.1 M organic acid of D-(+)- or L-(-)-camphor-sulphonic acid or D-(-)- and L-(+)-tartaric acid (TA). Molecular resolution STM imaging revealed aniline molecules were arranged differently in D-(+)- and L-(-)-camphor-sulphonic acid. The coverages and structures of aniline and coadsorbed anions could vary with the potential of gold electrodes. D-(+)- and L-(-)-camphor-sulphonic acid were able to induce 3-D helical molecular conformations of polyaniline at E > 0.95 V. On the other hand, different structures were obtained on Au(111) and Au(100) surfaces in electrolyte solutions containing aniline and D-(+)- or L-(-)-tartaric acid. Electropolymerization aniline also produced polyaniline wires with helix-like shape, which could be induced by the coadsorbed D-(-)- and L-(+)-tartaric acids. Interestingly, aniline molecules were organized differently on Au(100) electrode in D-(-)- and L-(+)-tartaric acids. Polyaniline grew linearly along the √10 direction in D-(-)- tartaric acid, followed by re-configuration into helix-like shape as oxidation of aniline continued. My studies show that chiral dopants of organic acids for polyaniline could induce specific conformational on Au(111) and Au(100) electrode surfaces. STM imaging has unveiled helical-shaped polyaniline chain in the presence of D- and L-organic acid, which could yield some fundamental insights into its potential applications in fabrication of chemical and biological sensors, chiral catalysis, pharmaceutics, and enantioselective separation.

並列關鍵字

aniline ； electropolymerization

參考文獻

〔23〕Lorenzo, M.O.;S. Haq, T.B.;Murray, P.;Raval, R.;Baddeley, C.J., J. Phys.

〔1〕Lethebyl, H., J. Chem. Soc. 1978, 26, 839.

〔4〕MacDiarmid, A.G.;Epstein, A.J., Faraday discuss. Chem. Soc. 1989, 88,

H.L.;Epstein, A.J., Appl. Phys. Lett. 1996, 68, 894-896.

〔7〕Racicot, R.;Brown, R.;Yang, S.C., Synth. met. 1997, 85, 1263-1264.