Dependence of Field Switched Ordered Arrays of Dinuclear Mixed-Valence Complexes on the Distance between the Redox Centers and the Size of the Counterions
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- 作者：Hua Qi ; Anuradha Gupta ; Bruce C. Noll ; Gregory L. Snider ; Yuhui Lu ; Craig Lent ; and Thomas P. Fehlner
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：November 2, 2005
- 年：2005
- 卷：127
- 期：43
- 页码：15218 - 15227
- 全文大小：264K
- 年卷期：v.127,no.43(November 2, 2005)
- ISSN：1520-5126
文摘
trans-[(H2NCH2CH2C
N)(dppe)2Ru(CC)6Ru(dppe)2(NCCH2CH2NH2)][PF6]2, 2[PF6]2, a derivative of trans-[Cl(dppe)2Ru(CC)6Ru(dppe)2Cl] functionalized for binding to a silicon substrate, has beenprepared and characterized spectroscopically, electrochemically, and with a solid state, single-crystalstructure determination. Covalent binding via reaction of one amine group to a boron-doped, smooth Si-Cl substrate is verified by XPS measurements and surface electrochemistry. Vertical orientation isdemonstrated by film thickness measurements. Synthesis of the 2[PF6]3 mixed-valence complex on thesurface is established by electrochemical techniques. Measurement of the ac capacitance of the film at 1MHz as a function of voltage across the film with a pulse-counter pulse technique demonstrates controlledelectric field generation of the two stable mixed-valence forms differing in the spatial location of one electron,that is, switching. As compared to [trans-Ru(dppm)2(CCFc)(NCCH2CH2NH2)][PF6][Cl], 1[PF6][Cl], themagnitude of the capacitance signal per complex observed on switching is shown to increase with increasingdistance between the metal centers. Additional experiments on 1[X][Cl] show that the potential for switching1[X][Cl] increases in the order [X]- = [SO3CF3]- < [PF6]- < [Cl]-. A simple electrostatic model suggeststhat the smaller is the counterion, the greater is the perturbation of the metal sites and the larger is thebarrier for switching.
N)(dppe)2Ru(CC)6Ru(dppe)2(NCCH2CH2NH2)][PF6]2, 2[PF6]2, a derivative of trans-[Cl(dppe)2Ru(CC)6Ru(dppe)2Cl] functionalized for binding to a silicon substrate, has beenprepared and characterized spectroscopically, electrochemically, and with a solid state, single-crystalstructure determination. Covalent binding via reaction of one amine group to a boron-doped, smooth Si-Cl substrate is verified by XPS measurements and surface electrochemistry. Vertical orientation isdemonstrated by film thickness measurements. Synthesis of the 2[PF6]3 mixed-valence complex on thesurface is established by electrochemical techniques. Measurement of the ac capacitance of the film at 1MHz as a function of voltage across the film with a pulse-counter pulse technique demonstrates controlledelectric field generation of the two stable mixed-valence forms differing in the spatial location of one electron,that is, switching. As compared to [trans-Ru(dppm)2(CCFc)(NCCH2CH2NH2)][PF6][Cl], 1[PF6][Cl], themagnitude of the capacitance signal per complex observed on switching is shown to increase with increasingdistance between the metal centers. Additional experiments on 1[X][Cl] show that the potential for switching1[X][Cl] increases in the order [X]- = [SO3CF3]- < [PF6]- < [Cl]-. A simple electrostatic model suggeststhat the smaller is the counterion, the greater is the perturbation of the metal sites and the larger is thebarrier for switching.