Kortekaas Luuk, Lancia Federico, Steen Jorn D, Browne Wesley R
Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747AG Groningen, The Netherlands.
J Phys Chem C Nanomater Interfaces. 2017 Jul 13;121(27):14688-14702. doi: 10.1021/acs.jpcc.7b04288. Epub 2017 Jun 12.
The coupling of substituted carbazole compounds through carbon-carbon bond formation upon one-electron oxidation is shown to be a highly versatile approach to the formation of redox polymer films. Although the polymerization of single carbazole units has been proposed earlier, we show that by tethering pairs of carbazoles double sequential dimerization allows for facile formation of redox polymer films with fine control over film thickness. We show that the design of the monomers and in particular the bridging units is key to polymer formation, with the diaminobenzene motif proving advantageous, in terms of the matching to the redox potentials of the monomer and polymer film and thereby avoiding limitations in film thickness (autoinsulation), but introduces unacceptable instability due to the intrinsic redox activity of this moiety. The use of a diimide protecting group both avoids complications due to -diamino-benzene redox chemistry and provides for a redox polymer in which the photoluminescence of the bis-carbazole moiety can be switched reversibly (on/off) with redox control. The monomer design approach is versatile enabling facile incorporation of additional functional units, such as naphthalene. Here we show that a multicomponent carbazole/naphthalene containing monomer () can form redox polymer films showing both p- and n- conductivity under ambient conditions and allows access to five distinct redox states, and a complex electrochromic response covering the whole of the UV/vis-NIR spectral region. The highly effective quenching of the photoluminescence of both components in poly- enables detailed characterization of the redox polymer films. The poly- films show extensive charge trapping, which can be read out spectroscopically in the case of films and is characterized as kinetic rather than chemical in origin on the basis of UV/vis-NIR absorption and resonance Raman spectroscopic analyses. The strong resonantly enhanced Raman scattering for the various oxidized and reduced states of enables nondestructive "read-out" of the state of the polymer, including that in which charges are trapped kinetically at the surface, making poly- highly suitable for application as a component in organic nonvolatile memory devices.
经单电子氧化通过碳 - 碳键形成实现取代咔唑化合物的偶联，被证明是一种形成氧化还原聚合物薄膜的高度通用的方法。尽管早期已有人提出单咔唑单元的聚合，但我们表明，通过连接咔唑对，双顺序二聚化能够轻松形成对膜厚度有精细控制的氧化还原聚合物薄膜。我们表明，单体的设计，特别是桥连单元，是聚合物形成的关键，二氨基苯基序被证明是有利的，这体现在与单体和聚合物薄膜的氧化还原电位相匹配，从而避免膜厚度的限制（自绝缘），但由于该部分的固有氧化还原活性而引入了不可接受的不稳定性。使用二酰亚胺保护基团既避免了因二氨基苯氧化还原化学引起的复杂性，又提供了一种氧化还原聚合物，其中双咔唑部分的光致发光可以通过氧化还原控制进行可逆切换（开/关）。单体设计方法具有通用性，能够轻松引入额外的功能单元，如萘。在此我们表明，一种含咔唑/萘的多组分单体（）能够形成在环境条件下显示p型和n型导电性的氧化还原聚合物薄膜，并能实现五种不同的氧化还原状态，以及覆盖整个紫外/可见 - 近红外光谱区域的复杂电致变色响应。聚 - 中两种组分的光致发光的高效猝灭使得能够对氧化还原聚合物薄膜进行详细表征。聚 - 薄膜显示出广泛的电荷俘获，对于薄膜情况可以通过光谱读出，并且根据紫外/可见 - 近红外吸收和共振拉曼光谱分析，其电荷俘获在本质上被表征为动力学而非化学性质。对于的各种氧化态和还原态的强共振增强拉曼散射使得能够对聚合物状态进行无损“读出”，包括电荷在表面动力学俘获的状态，这使得聚 - 非常适合用作有机非易失性存储器件的组件。
