Designing chemically selective liquid crystalline materials that respond to oxidizing gases
Designing chemically selective liquid crystalline materials that respond to oxidizing gases
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DOI：
10.1039/d1tc00544h
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发表时间：
2021-03-26
影响因子：
6.4
通讯作者：
Abbott, Nicholas L.
中科院分区：
文献类型：
--
作者：
Bao, Nanqi;Gold, Jake I.;Abbott, Nicholas L.
计算方法可以提供对界面处的热化学和反应动力学的第一原理见解，但是这种能力还没有被广泛利用来设计选择性地响应化学物种的软材料。在这里，我们解决这个机会，通过展示微米厚的液晶膜的设计支持金属高氯酸盐表面表现出选择性的定向反应，有针对性的氧化气体。初始电子结构计算预测Mn 2+、Co 2+和Ni 2+是有希望的候选表面结合位点，其（1）与含腈的介晶配位以定向液晶（LC）相和（2）在暴露于潮湿O-3时经历氧化还原触发的反应，导致腈基与表面的结合强度的变化。这些初步的预测进行了验证，暴露于空气中含有十亿分之几浓度的O-3的含腈液晶的取向转变的实验观察。金属盐和氧化性气体的反应自由能的附加第一原理计算预测，如果在不同空间位置的表面上图案化相同的金属阳离子组，将提供允许区分Cl-2和O-3的LC响应，而不响应环境氧化剂，如O-2和NO2。实验结果提供支持这一预测，和X-射线衍射测量证实，实验观察到的LC响应可以理解的相对热力学驱动力形成的MnO 2，CoOOH，或NiOOH从相应的金属阳离子结合位点在潮湿的O-3和Cl-2的存在下。
Computational methods can provide first-principles insights into the thermochemistry and kinetics of reactions at interfaces, but this capability has not been widely leveraged to design soft materials that respond selectively to chemical species. Here we address this opportunity by demonstrating the design of micrometer-thick liquid crystalline films supported on metal-perchlorate surfaces that exhibit selective orientational responses to targeted oxidizing gases. Initial electronic structure calculations predicted Mn2+, Co2+, and Ni2+ to be promising candidate surface binding sites that (1) coordinate with nitrile-containing mesogens to orient liquid crystal (LC) phases and (2) undergo redox-triggered reactions upon exposure to humid O-3 leading to a change in the strength of binding of the nitrile group to the surface. These initial predictions were validated by experimental observations of orientational transitions of nitrile-containing LCs upon exposure to air containing parts-per-billion concentrations of O-3. Additional first-principles calculations of reaction free energies of metal salts and oxidizing gases predicted that the same set of metal cations, if patterned on surfaces at distinct spatial locations, would provide LC responses that allow Cl-2 and O-3 to be distinguished while not responding to environmental oxidants such as O-2 and NO2. Experimental results are provided to support this prediction, and X-ray diffraction measurements confirmed that the experimentally observed LC responses can be understood in terms of the relative thermodynamic driving force for formation of MnO2, CoOOH, or NiOOH from the corresponding metal cation binding sites in the presence of humid O-3 and Cl-2.