物理化学学报 >> 2017, Vol. 33 >> Issue (5): 1010-1016.doi: 10.3866/PKU.WHXB201702102

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电势诱导的N-异丁酰基-L-半胱氨酸分子在金(111)表面的相转变

陈爱喜1,汪宏2,段赛3,张海明1,*(),徐昕4,迟力峰1,*()   

  1. 1 苏州大学功能纳米与软物质研究院,江苏省碳基功能材料与器件高技术研究重点实验室,江苏苏州215123
    2 明斯特大学物理研究所,威廉-克莱姆街10号,明斯特48149,德国
    3 皇家理工学院,生物工程学院理论化学与生物系,斯德哥尔摩S-106 91,瑞典
    4 复旦大学化学系,上海200433
  • 收稿日期:2016-12-19 发布日期:2017-04-20
  • 通讯作者: 张海明,迟力峰 E-mail:hmzhang@suda.edu.cn;chilf@suda.edu.cn
  • 基金资助:
    国家自然科学基金(91227201);国家自然科学基金(21527805)

Potential-Induced Phase Transition of N-Isobutyryl-L-cysteine Monolayers on Au (111) Surfaces

Ai-Xi CHEN1,Hong WANG2,Sai DUAN3,Hai-Ming ZHANG1,*(),Xin XU4,Li-Feng CHI1,*()   

  1. 1 Institute of Functional Nano & Soft Materials (FUNSOM), Jiangsu Key Laboratory for Carbon-Based Functional Materials & Devices, Soochow University, Suzhou 215123, Jiangsu Province, P. R. China
    2 Physikalisches Institut, Universit?t Münster, Wilhelm-Klemm Strasse 10, 48149 Münster, Germany
    3 Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm, Sweden
    4 Department of Chemistry, Fudan University, Shanghai 200433, P. R. China
  • Received:2016-12-19 Published:2017-04-20
  • Contact: Hai-Ming ZHANG,Li-Feng CHI E-mail:hmzhang@suda.edu.cn;chilf@suda.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(91227201);the National Natural Science Foundation of China(21527805)

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摘要：

自组装单层膜修饰的功能性基底在生物传感,色谱分析,生物相容性材料等方面均具有潜在应用.本文利用原位电化学扫描隧道显微镜(EC-STM)研究了电势诱导的N-异丁酰基-L-半胱氨酸(L-NIBC)分子在Au (111)表面自组装结构的相转变.我们把Au (111)基底分别浸润在纯的NIBC水溶液和pH = 7(磷酸盐缓冲溶液调节)的NIBC溶液中,分别制备了NIBC的α相和β相两种不同的自组装结构.EC-STM观测显示,当改变金的电极电势时, α相和β相的NIBC自组装单层膜出现了多种不同的结构变化.当电压从0.7 V (相对于饱和甘汞电极而言)降低到0.2 V时, α相由有序结构变为无序结构.而对于β相的样品,当E < 0.3 V时,为无序结构;当电极电势增大到0.4 V < E < 0.5 V时,出现γ相;继续增大到0.5 V < E < 0.7 V时,变为β相.另外, EC-STM图像也证实存在β相转变为α相的可能.综合密度泛函理论计算的结果,我们提出, β相转变为α相的原因可以解释为电极电势的变化引起了Au——COO-键的断裂,从而引发分子吸附构型变化而导致相变.

关键词: 自组装, 硫醇, 相转变, 电势诱导, 电化学扫描隧道显微镜, 密度泛函理论

Abstract:

Functional solid substrates modified by self-assembled monolayers (SAMs) have potential applications in biosensors, chromatography, and biocompatible materials. The potential-induced phase transition of N-isobutyryl-L-cysteine (L-NIBC) SAMs on Au (111) surfaces was investigated by in-situ electrochemical scanning tunneling microscopy (EC-STM) in 0.1 mol·L-1 H2SO4 solution. The NIBC SAMs with two distinct structures (α phase and β phase) can be prepared by immersing the Au (111) substrate in pure NIBC aqueous solution and NIBC solution controlled by phosphate buffer at pH 7, respectively. The as-prepared α phase and β phase of NIBC SAMs show various structural changes under the control of electrochemical potentials of the Au (111) in H2SO4 solution. The α phase NIBC SAMs exhibit structural changes from ordered to disordered structures with potential changes from 0.7 V (vs saturated calomel electrode, SCE) to 0.2 V. However, the β phase NIBC SAMs undergo structural changes from disordered structures (E < 0.3 V) to γ phase (0.4 V < E < 0.5 V) and finally to the β phase (0.5 V < E < 0.7 V). EC-STM images also indicate that the phase transition from the β phase NIBC SAMs to the α phase occurs at positive potential. Combined with density functional theory (DFT) calculations, the phase transition from the β phase to the α phase is explained by the potential-induced break of bonding interactions between ——COO- and the negatively charged gold surfaces.

Key words: Self-assembly, Thiol, Phase transition, Potential-induced, Electrochemical scanning tunneling microscopy, Density functional theory