Acta Phys. -Chim. Sin. ›› 2017, Vol. 33 ›› Issue (5): 1010-1016.doi: 10.3866/PKU.WHXB201702102

• ARTICLE • Previous Articles     Next Articles

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)

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

MSC2000: 

  • O647