Investigation of the Charge Transfer Properties of Electrodes Modified by the Spontaneous Adsorption of Unsymmetrical Dialkyl Sulfides
Investigation of the Charge Transfer Properties of Electrodes Modified by the Spontaneous Adsorption of Unsymmetrical Dialkyl Sulfides
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不对称二烷基硫醚自发吸附修饰电极的电荷转移性能研究
DOI：
10.1021/la00020a050
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发表时间：
1994
期刊：
影响因子：
3.9
通讯作者：
M. Anderson
中科院分区：
文献类型：
--
作者：
Minhui Zhang;M. Anderson
通过不对称二烷基硫醚的自发吸附修饰的电极用于研究两种单层特性：结构无序和溶剂相容性，这对于确定单层存在下发生法拉第电荷传输的能力可能很重要。制备并研究了两组二烷基硫醚：结构为 CH3 (CH2) i7S (CH2) nCH3 的纯烃二烷基硫醚，其中 = 7、9 和 17，以及结构为 CH3 (CH2) i7S (CH2) mCOOH 的含酸二烷基硫醚，其中 m= 7、10 和 15。烃二烷基硫醚的反射红外光谱表明单层当非原位测量时，结构是无序的，并且不受接触水溶液的存在的很大影响。含二烷基硫醚的酸的红外光谱表明，当非原位测量时，其具有部分有序的结构，但当与水溶液接触时，单层变得无序。在单层与十六烷形成的接触角中发现了两组二烷基硫醚的单层无序的额外证据。含二烷基硫醚的酸的水接触角测量表明酸基团受到周围烃链的保护，但酸基团与单层溶液界面的接近程度影响界面性质。电化学结果表明，没有溶液渗透到纯烃单层中，而含酸单层中发生大量渗透。对于含酸的单层，当酸基团靠近单层-溶液界面时，溶液渗透增加。这些结果表明单层结构内极性基团的存在增加了单层修饰电极的电荷转移性能。
Electrodes modified by the spontaneous adsorption of unsymmetricaldialkyl sulfides are used to investigate two monolayer properties, structural disorder and solvent compatibility, that may be of importance in determining the ability for faradaic charge transport to occur in the presence of the monolayer. Two groups of dialkyl sulfides are prepared and studied: a purely hydrocarbon dialkyl sulfide with the structure CH3 (CH2) i7S (CH2) nCH3, where=7, 9, and 17, and an acid containing dialkyl sulfide with the structure CH3 (CH2) i7S (CH2) mCOOH, where m= 7, 10, and 15. Reflection infrared spectroscopy of the hydrocarbon dialkyl sulfidereveals that themonolayer structure is disordered, when measured ex situ, and is not largely affected by the presence of contacting aqueous solutions. Infrared spectroscopy of the acid containing dialkyl sulfides suggests a partially ordered structure when measured ex situ, but the monolayer becomes disordered when in contact with aqueous solutions. Additional evidence of monolayer disorder for both groups of dialkylsulfides is found in the contact angle the monolayers make with hexadecane. Aqueous contact angle measurements for the acid containing dialkyl sulfides indicate that the acid group is protected by the surrounding hydrocarbon chains, but the proximity of the acid group to the monolayer-solution interface influences the interfacial properties. Electrochemical results indicate that no solution permeation occurs into the purely hydrocarbon monolayer, while substantial permeation occurs with the acid containing monolayers. For the acid containing monolayers, solution permeation increases as the acid group is placed closer to the monolayer-solution interface. These results suggest that the presence of a polar group within the monolayer structure increases the charge transfer properties of the monolayer modified electrode.