我们感激地感谢赠款、ERC-2012-StG_20111012 FOLDHALO (307108 号赠款协议) 的支持。

注: 在氮气气氛下, 在烘干玻璃器皿中进行反应。请遵照每种化学品的 MSDS 中所描述的安全措施。
1. 1-烷基3咪唑碘盐的合成 (1 米,图 3)
<ol><li>在一个三颈, 圆底烧瓶装有回流冷凝器装有氮气入口, 温度计, 磁搅拌棒, 和加热油浴, 溶解1.5 克 (0.018 摩尔, 1 equiv) 新鲜蒸馏的1-甲基咪唑和1。3equiv 的 1-iodoalkane (链长度从 C2 到 C12) 在10毫升的乙腈。</li>
	<li>将反应混合物加热到回流 (75-80 °c 内部温度), 在氮气气氛下过夜, 然后将混合物冷却到室温。</li>
	<li>使用旋转蒸发器将所产生的混合物中的挥发性材料从减少的压力降低到50摄氏度。 注: 鎓盐具有高度的吸湿和快速吸收空气中的水分。因此, 建议将其存储在干燥中, 直到使用。</li>
</ol>2. 1-米· 2-n 的预算外综合体的合成
<ol><li>
过程 1: 从解决方案 (仅在图 1中的1-2 ·2-8 中)
	<ol>
<li>1-乙基3咪唑碘 (1-2, 兆瓦 = 238.07 克/摩尔) 的溶液, 通过溶解50毫克 (0.21 毫摩尔, 1 equiv) 1-2 在乙腈的0.5 毫升. </li>
		<li>perfluorooctyl 碘化物 (2-8, 兆瓦 = 545.96 克/摩尔) 的溶液, 通过溶解229毫克 (0.42 毫摩尔, 2 equiv) 的 2-8 在乙腈的0.5 毫升. </li>
		<li>把两个溶液混合在一个瓶子里, 把瓶子放在一个装满石蜡油的罐子里。</li>
		<li>使溶剂在室温下在石蜡油中慢慢扩散。经过3至7天的时间, 得到了适合 X 射线衍射分析的优质单晶。</li>
	</ol>
</li>
	<li>
程序 2: 熔体方法学 注意: 这种方法需要一个空气密封系统, 以减轻 iodoperfluoroalkanes 的波动性。<ol>
<li>将每个 1-烷基-3-咪唑碘 (1m) 与适当的 iodoperfluoroalkanes (2n) 混合在一个有磁性搅拌棒的透明硼硅酸盐玻璃瓶中, 在1:2 摩尔比率中。</li>
		<li>关闭瓶子, 并把它在激烈搅拌下的油浴。</li>
		<li>热量在70摄氏度使用热板15分钟, 然后冷却的混合物, 以室温。</li>
	</ol>
</li>
</ol>3. 1H 和19F 核磁共振实验
注: 1H nmr 和19F 核磁共振谱记录在25°c 上, 其工作于499.78 兆赫, 用于 1 H 和 470.21 mhz, 用于, 并使用 CDCl 19 作为溶剂。TMS 和 CFCl3被用作校准1H 核磁共振和19F 核磁共振的化学位移的内部标准。含有氢和氟核的双 (22、2-trifluoroethyl) 醚作为内部标准, 用于在 cocrystals 中建立1m 和2n 之间的比值。
<ol><li>
核磁共振分析和光谱标定样品的制备
	<ol>
<li>溶解约10毫克的每一个复杂的1米· 2-n 在0.5 毫升的 CDCl3。</li>
		<li>添加1µL 22, 2-trifluoroethyl 醚使用微。</li>
		<li>锁定该示例, 设置在表 1中报告的捕获参数, 并记录1H 和19F nmr 连续光谱, 而不从磁铁中删除核磁共振管, 以便在相同的操作条件下运行。</li>
		<li>校准集成参数, 以便在1H 核磁共振谱中的 CH2O 四重奏 (22, 2-trifluoroethyl) 醚 (δ = 4.3 ppm) 对应于四, 在19F NMR 谱中, CF3三重 (δ = −74.5 ppm) 的 22, 2-trifluoroethyl 醚对应于六。</li>
		<li>计算在19F 核磁共振谱中从2-n (δ = −61.2 ppm) 派生的 CF2I 信号区域的比率) 和从1m ( 1H 核磁共振谱中的δ≈ 4.0 ppm) 派生的 CH3信号区域, 为了计算每个复合体中2-n 和1m 之间的比率。</li>
	</ol>
</li>
</ol>4. 热级偏振光学显微镜 (POM) 样品的制备
<ol><li>在两个微盖玻璃 (18 毫米 x 18 毫米) 之间放置一个超分子复合体1-m• 2n 的铲头量, 以制备样品薄层。</li>
	<li>将样品放在两个交叉偏振片之间的热阶段, 并将样品加热熔化。</li>
	<li>将样品提交给反复加热/冷却循环, 以促进相变。晶体和液晶相会与偏振光相互作用, 导致亮度和颜色梯度, 而各向同性相则会出现暗色。</li>
</ol>

作者没有什么可透露的。

我们报告了一个简单和通用的协议, 以合成的预算外氟化签订, 其中 mesomorphicity 是由超分子阴离子 [CnF2 n + 1-I∙∙∙I∙∙∙InF2 n + 1]-。
根据 1-烷基-3-咪唑盐的离子液体可以表现出液态结晶行为, 这是公认的。然而, 无论阴离子, 没有 mesophases 被观察到的化合物与烷基链短于12碳原子。因此, 所报道的材料最引人注目的方面是, 它是外相阴离子的各向异性, 确定中间相形成。事实上, 严格的几何约束的预算外强加的分子间相互作用发生沿扩展的 c-I 键, 在西格玛孔, 与角度接近180°。碘化阴离子作为二齿的预算外受体, 结合两个氟模块, 显示线性排列围绕中央碘化阴离子。此外, 烷基链比等效 HC 链更硬, 并采用扭曲的螺旋结构, 由于13配置 CF2组9,52之间的排斥, 进一步促进了生成刚性, 棒状 superanions。
这完全同意的观察, 其中包含 iodoperfluorodecane (2-10) 显示的过渡温度高于那些包含 iodoperfluorooctane (2-8), 因为前者是更多的各向异性。此外, 已知趋势45、53 fluoroalkanes 打包成层状阶段决定了 SmB 和 SmA 阶段的获取。
本文报道的 superfluorinated 签订首次证明了在鎓盐的基础上签订的应用。多亏了一个精确的超分子设计的基础上的高方向性的预算外和 fluorophobic 效应, 有可能获得 enantiotropic 液晶基于刚性, 非芳香, 预算外超分子 synthon 作为液晶核心。液晶行为与烷基链的长度无关。
这里提出的超分子方法代表了一个有吸引力的平台, 设计新的液晶材料, 并可以为开发先进的功能材料, 如室温离子提供了新的机会导体, photoresponsive 签订, 液晶电解质, 用于能源设备中。

分子间相互作用在测定散装材料的理化性质方面起着非常重要的作用。当新的交互作用变为可用时, 新的结构 (即新函数) 将变为可用。因此, 探索分子间识别过程中的新的、特定的非共价键相互作用可能会在材料科学、催化、药物设计、超分子化学和晶体等不同领域开辟新的视角。工程.对于最近成为控制聚合和自组装现象的常规工具的预算外, 此情况为1,2,3,4,5。
根据 IUPAC 定义6: 当有证据表明在一个分子实体中与卤素原子相关的亲区域与另一个或相同的亲核区域之间有净吸引力的相互作用时, 就会发生卤素键,分子实体。在图 1中给出了预算外的示意图, 其中 X 是亲卤素原子 (路易斯酸, 预算外捐助者), Y 是电子密度的捐助者 (刘易斯基数, 预算外受体)。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/55636/55636fig1.jpg"> 图 1: 卤素键的示意图表示形式。 亲卤素原子 (预算外-捐赠者) 与各种各样的分子支架 (R) 是共价键相连的, 而预算外受体 (Y) 可以是中性或阴离子的种类。此数字已从引用2中重印。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
乍一看, 这个定义似乎处理一些令人费解的方面, 因为卤素原子, 因为它们的高电负性, 通常被认为是高电子密度的地点。然而, 卤素原子作为 electrophiles 的行为是相当普遍的, 并且通过 "σ孔" 概念7的介绍, 优雅地合理化了 Politzer et .。
当卤素原子参与共价键时, 电子重分布发生, 电子密度成为各向异性8,9,10,11。原子的形状变成扁球形, 一个正静电电位区域 (所谓的σ孔) 沿着共价键的延伸发展, 在卤素原子的最外层 (图 2A)。这个正区域被一个负静电电位带所包围, 与共价键的正交。这个模型似乎解决了预算外的 "谜", 因为它解释了共价键结合卤素原子的非共价键相互作用模式, 以及相关的方向偏好, i. e, 与亲核试剂和侧向的线性相互作用与 electrophiles 的互动。
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/55636/55636fig2.jpg"> 图 2: 卤素原子周围电子密度的各向异性分布.(A) 在共价键的卤素原子周围电子密度各向异性分布的示意图表示以及由此产生的相互作用的模式。(B) 等密度表面的分子静电电位图, 0.001 au 用于 cf 4、cf 3 Cl、cf 3 Br 和 cf 3 i. 颜色范围: 红色, 大于27大卡/摩尔;黄色, 在20和14大卡/摩尔之间;绿色, 在12和6大卡/摩尔之间;蓝色, 阴性此数字已从引用2中进行了修改。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig2large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
在设计功能超分子材料时, 预算外已迅速从科学的好奇心成长为最有趣的 noncovalent 互动之一12,13,14,15,16, 由于其独特的功能,即高方向性、可调谐的交互强度、疏水性和捐助者原子维度1。通过考虑σ孔的聚焦性质, 可以很容易地理解预算外的高方向性, 而交互强度经常与σ孔的大小相关。σ孔的尺寸 (空间范围) 和大小 (最大静电电位 VS、最大) 的值受卤素原子的极化和电负性和电子提取能力的影响。卤素17的邻域中的取代项 (图 2B)。作为一个普遍的趋势, 随着卤素原子变得更加极化, 取代分子变得更加电子化, 卤素σ孔变得更加正面。因此, 对于给定的 R, VS, max增加的顺序 F < Cl S, max变得更加正面。因此, haloperfluorocarbons, 特别是碘 perfluoroalkanes 和芳烃, 可以充当强大的预算外捐助者, 形成特别强的交互作用18,19,20 , 特别是疏水性加合物.
二十世纪九十年代下旬的21中报告了一例 PFC-HC 自组装给 cocrystals 的案例。在氯仿中混合摩尔量为 12-diiodotetrafluoroethane 和n、n、n'、n '-四甲基乙二胺时, 一个超分子复合体被隔离, 因为白色晶体在室温下稳定在空气中。单晶 x 射线分析表明, 在1维 (1D) 无限链中, 两个组分交替存在, 氮和碘原子之间的相互作用主要负责保持氟双碘的位置。这证明, 氮碘的预算外相互作用足够强, 以克服 PFC 和 HC 化合物之间存在的低亲和力, 并建议可以成功地利用预算外, 作为一个简单的途径引入氟化基团到任何新的超分子材料22,23,24, 包括液晶材料。
氟化取代剂, 事实上, 已成功地纳入液晶分子, 因为良好的稳定性, 由 C F 键, 以及小规模和低极化的氟原子, 这导致非常低的分子间色散相互作用25,26,27。此外, PFC 和 HC 链之间的隔离允许控制超分子液晶相, 增强了液晶材料的 smectic 特性28,29,30。一般理解, 物理/化学性质和 mesomorphism 都受到分子体系结构29,31的强烈影响。因此, 一个适当的分子设计是必不可少的产生新的超分子液晶具有量身定做的性质。这些软材料的基本主题是在一个相当刚性, 类似杆状的基团链接到一个或两个灵活的脂肪族链32,33,34。液晶化合物的传统设计主要是用中性种进行的, 但研究表明, 离子对也可以表现出液晶行为, 在离子液体和液体的界面上产生具有性质的材料。晶体35,36,37。
考虑到最近关于预算外液晶的结果24,38,39, 以及阴离子作为预算外受体的特定能力, 它似乎特别有趣的是利用这种非共价键的互动在设计新类型的签订。
1-烷基-3-咪唑碘 (1m) 的各种链长度, 称为离子液体40, 用于合成复合物 (图 3)41,42。请注意, 只有1-12, 轴承一个 C12 烷基链, 展出液体结晶度与 smectic a (Sm a) 相 (晶体 (Cr) 到 SmA 过渡温度 = 27 °c;Sm A 到各向同性液体 (ISO) 转折温度 = 80 °c;Cr ·27· SmA ·80· Iso)43。鎓盐的反应与 iodoperfluorooctane (2-8) 和 iodoperfluorodecane (2-10), 这是众所周知的预算外捐助者44,45。
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/55636/55636fig3.jpg"> 图 3: 合成方案.启动离子液体的化学公式 (1-m)、iodoperfluoroalkanes (2-n) 和相关的预算外-络合物1-m•2-n.<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig3large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
碘化阴离子在 haloperfluoroalkanes44的超分子结构的形成中, 可望作为预算外受体参与。然而, 预测协调的预算外捐助物种的数量和拓扑结构仍然具有挑战性。事实上, 卤素阴离子通常涉及三 XBs46,47,48, 但更高的协调数也被观察到49,50。
在这里, 我们描述了一个获得高度氟化的预算外签订的程序和一个详细的程序, 以确定和描述预算外的发生。这里报告的分析序列和用于确定预算外的方法可被视为一般程序, 可用于任何类型的预算外系统的特性。

<table border="0" cellpadding="0" cellspacing="0" width="819">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">1-Methyl-imidazole&#160;</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">M50834-500G</td>
			<td style="width:299px;">liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iodoethane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">I7780-100G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iodobutane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">167304-100G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iodohexane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">238287-100G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iodooctane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">238295-25G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iododecane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">238252-100G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">1-Iodododecane</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">238260-100G</td>
			<td>liquid reagent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Acetonitrile</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">271004-1L</td>
			<td>organic solvent</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perfluorooctyl iodide&#160;</td>
			<td>Apollo Scientific</td>
			<td style="width:139px;">PC6170</td>
			<td>fluorinated reagent/halogen-bond donor&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Perfluorodecyl iodide</td>
			<td>Apollo Scientific</td>
			<td style="width:139px;">PC5970</td>
			<td>fluorinated reagent/halogen-bond donor&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Bis(2,2,2-trifluoroethyl) ether&#160;</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">287571-5G</td>
			<td>Internal standard for NMR</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Chloroform-d</td>
			<td style="width:167px;">Sigma-Aldrich</td>
			<td style="width:139px;">151823-100G</td>
			<td>Solvent for NMR</td>
		</tr>
	</tbody>
</table>

from molecules to materials: engineering new ionic liquid crystals through halogen bonding

在此, 我们证明了一种基于卤素键合 (XB) 的自底向上方法, 可以成功地应用于新型离子液晶 (签订) 的设计中。利用 haloperfluorocarbons 的高特异性和阴离子作为碘的能力, 我们获得了基于 1-烷基-3-咪唑 iodoperfluorocarbons 的超分子配合物, 克服了众所周知的碳氢化合物 (HCs) 与全氟化碳 (不混溶) 之间的相互关系。预算外的高方向性加上 fluorophobic 效应, 使我们能够获得 enantiotropic 液晶, 其中刚性, 非芳香, XB 超分子负离子作为液晶核心。
1-乙基-3-咪唑碘与 iodoperfluorooctane 的 x 射线结构分析表明存在层状结构, 这是众所周知的烷基链分离倾向的表现。这与观察 smectic mesophases 是一致的。此外, 所有报告的配合物融化低于100摄氏度, 大多数是液晶即使在室温下, 尽管起始材料是非液晶的性质。
这里所报道的超分子战略为基团设计提供了新的设计原则, 允许全新的功能材料类。

采用差分扫描量热法 (DSC)、POM 和热重分析 (TGA) 以及1H 和19F NMR 来表征所得到的络合物。1-2•2-8 的优质单晶在乙腈的起始组分的1:2 个解答获得了从溶剂的缓慢的蒸发在室温下。
DSC 分析了1-2 和2-8 与不同化学计量比率的混合物, 使我们可以得出鎓盐和 iodoperfluoroalkane 之间的正确协调化学成分为1:2。事实上,图 4A中的1:1 复杂度的 DSC 级数显示了 uncomplexed 鎓盐1-2 (峰值在57摄氏度) 的存在, 而在1:3 复合体中有一个多余的纯2-8 (熔点24°c)。另一方面, 1:2 复合体的级数显示出一个与起始化合物不同的峰值, 表明形成了一种新的纯晶体物种。
TGA 分析证实了这一结果。实际上, 只有在将1-12 和2-10 与1:2 比率混合后, 才获得了一个均匀样本, 它在比 uncomplexed iodoperfluorodecane 高的温度下定量地释放了氟化构造块 (图 5A 和 5B)。
19F 核磁共振作为一种简单、有效和灵敏的工具, 用于检测预算外加合物的形成。iodoperfluoroalkanes 电子亏碘与 i型-阴离子之间的 XB 强烈影响 CF2I 组 (δ = −60,0 ppm) 的信号, 并引起19F 核磁共振共振的可检测前场移位。测量复杂1-2•2-8 的Δδ值 1.2 ppm, 确认有吸引力的 noncovalent 相互作用涉及卤素原子作为亲物种 (图 6)。此外, 通过记录连续的1H 和19F 的核磁共振分析, 在22、2-trifluoroethyl 醚的存在下, 作为信号集成的内部标准, 预算外受体和捐助者模块之间的1:2 化学计量法进一步证实.
对1-2•2-8 的单晶 x 射线分析证实, 预算外驱动了三联超分子复合体的形成, 其中碘化阴离子作为二齿的 XB 受体, 结合了两个含氟链。I···I-距离几乎是相同的 [3.4582 (9) Å和 3.4625 (10) Å], 并且大致对应于27% 缩短关于碘原子和碘化阴离子的 vdW 和鲍林半径的总和, 分别为51。I···的高方向性被证实了。I-角度为 174.1 (1) °和 175.4 (2) °, 分别为 (图 7A)。两个同样居住的构象被观察为鎓阳离子, 近似地说谎在同一个平面和由一个非结晶性双重轴相关。图 7B 显示了离子和中性部件之间的分离, 以及在晶体内的 HC 和 PFC 链之间的分隔 (排除障碍)。
DSC 和 POM 的研究表明, 所有配合物在温度低于100摄氏度 (图 8A) 时熔化, 这是离子液体的典型特征。此外, 它们都显示了 enantiotropic 的液晶行为, 有些在室温下, 带有 SmB 和 SmA 相 (图 8A)。在冷却时, SmA-SmB 转换由风扇背面的特征条纹 (图 8B, 左) 标识。在过渡下的冷却过程中, 条纹消失了。
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/55636/55636fig4.jpg"> 图 4: 差分扫描量热。DSC thermograms 通过混合1-2 和2-8 在不同的化学计量比率中制备的样品: 1:3 样品 (顶部), 1:2 样品 (中间) 和1:1 样品 (底部)。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig4large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/55636/55636fig5.jpg"> 图 5:热分析.DSC 加热/冷却循环 (A) 和 TGA 分析 (B) 上的一个样本, 通过混合1-12 和2-10 在1:2 摩尔比率。此数字已从引用37中进行了修改。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig5large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/55636/55636fig6.jpg"> 图 6:19F 核磁共振分析.19F 核磁共振波谱在 CDCl3的2-8 (顶部) 和相关卤素结合的复杂1-2•2-8 (底部)。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig6large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 7" class="xfigimg" src="/files/ftp_upload/55636/55636fig7.jpg"> 图 7: x 射线单晶分析.(A) 复杂1-2•2-8 的非对称单元, 显示了三联 superanion 的形成, 其中两个氟化链与中央 I-阴离子相连 (报告了无序阳离子的单个 conformer);(B) 鎓盐1-2 和 iodoperfluorooctane 2-8 沿晶体B轴隔离;(C) 侧面视图, 显示结构的离子和氟碳区域。颜色代码: 灰色, 碳;蓝色, 氮气;洋红, 碘;绿色、氟;白色氢气卤素债券描绘为灰色线。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig7large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<img alt="Figure 8" class="xfigimg" src="/files/ftp_upload/55636/55636fig8.jpg"> 图 8: 偏振光学显微镜.(A)由热级 POM (蓝色为固态, 红色为 SmB, 橙色为 SmA) 的卤素粘结配合物的 thethermal 过渡的 1-m•2-n 的图表。(B) 为1-12•2-10 从各向同性状态冷却时观察到的 smectic 相的光学纹理。左: SmB 阶段在77°c;右: SmA 相在83°c。刻度条: 100 µm。此数字已从引用37中进行了修改。<a href="//cloudflare.jove.com/files/ftp_upload/55636/55636fig8large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always"><tbody>
<tr>
<td></td>
			<td>光谱宽度 (赫)</td>
			<td>扫描号码</td>
			<td>脉冲延时 (s)</td>
		</tr>
<tr>
<td>1h</td>
			<td>7</td>
			<td>16</td>
			<td>1</td>
		</tr>
<tr>
<td>19f</td>
			<td>95</td>
			<td>16</td>
			<td>1</td>
		</tr>
</tbody></table>表 1: 获取参数1H 和19F 核磁共振实验

Watch this Scientific Journal Video about From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding at JoVE.com

From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

一种基于卤素结合超分子阴离子的新型液晶聚合成协议 [C n F2 n +1-I···我·报告了nF2 n + 1]−。

从分子到材料: 通过卤素键合工程新的离子液体晶体

Herein, we demonstrate that a bottom-up approach, based on halogen bonding (XB), can be successfully applied for the design of a new type of ionic liquid ...

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68.9K 次观看.  Politecnico di Milano. 一种基于卤素结合超分子阴离子的新型液晶聚合成协议 [C n F2 n +1-I···我·报告了nF2 n + 1]−。

视频: From Molecules to Materials: Engineering New Ionic Liquid Crystals Through Halogen Bonding

Preparation of Silica Nanoparticles Through Microwave-assisted Acid-catalysis

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle diameters ranging from 30-250 nm by varying the reaction conditions. Through the selection of a microwave compatible solvent, silicic acid precursor, catalyst, and microwave irradiation time, these microwave-assisted methods were capable of overcoming the previously reported shortcomings associated with synthesis of silica nanoparticles using microwave reactors. The siloxane precursor was hydrolyzed using the acid catalyst, HCl. Acetone, a low-tan &#948; solvent, mediates the condensation reactions and has minimal interaction with the electromagnetic field. Condensation reactions begin when the silicic acid precursor couples with the microwave radiation, leading to silica nanoparticle sol formation. The silica nanoparticles were characterized by dynamic light scattering data and scanning electron microscopy, which show the materials&#39; morphology and size to be dependent on the reaction conditions. Microwave-assisted reactions produce silica nanoparticles with roughened textured surfaces that are atypical for silica sols produced by St&#246;ber&#39;s methods, which have smooth surfaces.

Silica nanoparticles were prepared using acid-catalysis of a siloxane precursor and microwave-assisted synthetic techniques resulting in the controlled growth of nanomaterials ranging from 30-250 nm in diameter. The growth dynamics can be controlled by varying the initial silicic acid concentration, time of the reaction, and temperature of reaction.

Microwave-assisted synthetic techniques were used to quickly and reproducibly produce silica nanoparticle sols using an acid catalyst with nanoparticle ...

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化学

Diffuse Reflectance Infrared Spectroscopic Identification of Dispersant/Particle Bonding Mechanisms in Functional Inks

In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers. A typical inkjet ink is a colloidal dispersion containing approximately ten components including solvent, the nano to micron scale particles which will comprise the printed layer, polymeric dispersants to stabilize the particles, and polymers to tune layer strength, surface tension and viscosity. To rationally and efficiently formulate such an ink, it is crucial to know how the components interact. Specifically, which polymers bond to the particle surfaces and how are they attached? Answering this question requires an experimental procedure that discriminates between polymer adsorbed on the particles and free polymer. Further, the method must provide details about how the functional groups of the polymer interact with the particle. In this protocol, we show how to employ centrifugation to separate particles with adsorbed polymer from the rest of the ink, prepare the separated samples for spectroscopic measurement, and use Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) for accurate determination of dispersant/particle bonding mechanisms. A significant advantage of this methodology is that it provides high level mechanistic detail using only simple, commonly available laboratory equipment. This makes crucial data available to almost any formulation laboratory. The method is most useful for inks composed of metal, ceramic, and metal oxide particles in the range of 100 nm or greater. Because of the density and particle size of these inks, they are readily separable with centrifugation. Further, the spectroscopic signatures of such particles are easy to distinguish from absorbed polymer. The primary limitation of this technique is that the spectroscopy is performed ex-situ on the separated and dried particles as opposed to the particles in dispersion. However, results from attenuated total reflectance spectra of the wet separated particles provide evidence for the validity of the DRIFTS measurement.

Formulation of stable, functional inks is critical to expanding the applications of additive manufacturing. In turn, knowledge of the mechanisms of dispersant/particle bonding is required for effective ink formulation. Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) is presented as a simple, inexpensive way to gain insight into these mechanisms.

弥漫分散剂/粒子绑定机制反射红外光谱鉴定功能性油墨

In additive manufacturing, or 3D printing, material is deposited drop by drop, to create micron to macroscale layers.  A typical inkjet ink is a colloidal ...

Highly Stereoselective Synthesis of 1,6-Ketoesters Mediated by Ionic Liquids: A Three-component Reaction Enabling Rapid Access to a New Class of Low Molecular Weight Gelators

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form catalytically active N-Heterocyclic Carbenes (NHCs). Here we have used ILs as precatalysts in the addition of &#945;,&#946;-unsaturated aldehydes to chalcones to form 1,6-ketoesters, incorporating an anti-diphenyl moiety in a highly stereoselective fashion. The reaction has a broad substrate scope and several functional groups and heteroaromatics can be integrated into the ketoester backbone in generally good yields with maintained stereoselectivity. The reaction protocol is robust and scalable. The starting materials are inexpensive and the products can be obtained after simple filtration, avoiding solvent-demanding chromatography. Furthermore, the IL can be recycled up to 5 times without any loss of reactivity. Moreover, the 1,6-ketoester end product is a potent gelator in several hydrocarbon based solvents. The method enables rapid access to and evaluation of a new class of low molecular weight gelators (LMWGs) from recyclable and inexpensive starting materials.

Ionic liquids (ILs) mediate fast, simple and cheap access to 1,6-ketoesters in high diastereoselectivities and good yields. The reaction protocol is robust and the 1,6-ketoesters can be obtained in gram scale after a simple filtration protocol. Moreover, the 1,6-ketoesters are potent gelators in hydrocarbon solvents.

1,6-酮酯高立体选择性合成离子液体介导:三组分反应启用快速进入低分子量胶凝剂的新型类

In organic chemistry ionic liquids (ILs) have emerged as safe and recyclable reaction solvents. In the presence of a base ILs can be deprotonated to form ...

From Constructs to Crystals &#8211; Towards Structure Determination of &#946;-barrel Outer Membrane Proteins

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% percent of known structures. There are two types of membrane proteins, &#945;-helical and &#946;-barrel. While &#945;-helical membrane proteins can be found in nearly all cellular membranes, &#946;-barrel membrane proteins can only be found in the outer membranes of mitochondria, chloroplasts, and Gram-negative bacteria. One common bottleneck in structural studies of membrane proteins in general is getting enough pure sample for analysis. In hopes of assisting those interested in solving the structure of their favorite &#946;-barrel outer membrane protein (OMP), general protocols are presented for the production of target &#946;-barrel OMPs at levels useful for structure determination by either X-ray crystallography and/or NMR spectroscopy. Here, we outline construct design for both native expression and for expression into inclusion bodies, purification using an affinity tag, and crystallization using detergent screening, bicelle, and lipidic cubic phase techniques. These protocols have been tested and found to work for most OMPs from Gram-negative bacteria; however, there are some targets, particularly for mitochondria and chloroplasts that may require other methods for expression and purification. As such, the methods here should be applicable for most projects that involve OMPs from Gram-negative bacteria, yet the expression levels and amount of purified sample will vary depending on the target OMP.

&#946;-barrel outer membrane proteins (OMPs) serve many functions within the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Here, we hope to alleviate a known bottleneck in structural studies by presenting protocols for the production of &#946;-barrel OMPs in sufficient quantities for structure determination by X-ray crystallography or NMR spectroscopy.

从构造到晶体 - 迈向β桶外膜蛋白的结构解析

Membrane proteins serve important functions in cells such as nutrient transport, motility, signaling, survival and virulence, yet constitute only ~1% ...

Synthesis and Exfoliation of Discotic Zirconium Phosphates to Obtain Colloidal Liquid Crystals

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and engineers. Growth of such anisotropic nanocrystals through a simple chemical method is a challenging task. In this study, we fabricate discotic nanodisks of zirconium phosphate [Zr(HPO4)2&#183;H2O] as a model material using hydrothermal, reflux and microwave-assisted methods. Growth of crystals is controlled by duration time, temperature, and concentration of reacting species. The novelty of the adopted methods is that discotic crystals of size ranging from hundred nanometers to few micrometers can be obtained while keeping the polydispersity well within control. The layered discotic crystals are converted to monolayers by exfoliation with tetra-(n)-butyl ammonium hydroxide [(C4H9)4NOH, TBAOH]. Exfoliated disks show isotropic and nematic liquid crystal phases. Size and polydispersity of disk suspensions is highly important in deciding their phase behavior.

A two dimensional model material of discotic zirconium phosphate was developed. The inorganic crystal with lamellar structure was synthesized by hydrothermal, reflux, and microwave-assisted methods. On exfoliation with organic molecules, layered crystals can be converted to monolayers, and nematic liquid crystal phase was formed at sufficient concentration of monolayers.

合成与盘状磷酸盐锆剥落获取胶体液晶

Due to their abundance in natural clay and potential applications in advanced materials, discotic nanoparticles are of interest to scientists and ...

Characterizing Electron Transport through Living Biofilms

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under physiologically relevant conditions.1 These measurements are performed on living biofilms in aqueous medium using source and drain electrodes patterned on a glass surface in a specialized configuration referred to as an interdigitated electrode (IDA) array. A biofilm is grown that extends across the gap connecting the source and drain. Potentials are applied to the electrodes (ES and ED) generating a source-drain current (ISD) through the biofilm between the electrodes. The dependency of electrical conductivity on gate potential (the average of the source and drain potentials, EG = [ED + ES]/2) is determined by systematically changing the gate potential and measuring the resulting source-drain current. The dependency of conductivity on gate potential provides mechanistic information about the extracellular electron transport process underlying the electrical conductivity of the specific biofilm under investigation. The electrochemical gating measurement method described here is based directly on that used by M. S. Wrighton2,3 and colleagues and R. W. Murray4,5,6 and colleagues in the 1980&#39;s to investigate thin film conductive polymers.

A protocol for measuring electrical conductivity of living microbial biofilms under physiologically relevant conditions is presented.

通过活生物膜表征电子传输

Here we demonstrate the method of electrochemical gating used to characterize electrical conductivity of electrode-grown microbial biofilms under ...

Determination of Thermodynamic Properties of Alkaline Earth-liquid Metal Alloys Using the Electromotive Force Technique

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline earth-liquid metal alloys as functions of both composition and temperature in order to acquire thermodynamic data. The cell consists of a chemically stable solid-state CaF2-AF2 electrolyte (where A is the alkaline-earth element such as Ca, Sr, or Ba), with binary A-B alloy (where B is the liquid metal such as Bi or Sb) working electrodes, and a pure A metal reference electrode. Emf data are collected over a temperature range of 723 K to 1,123 K in 25 K increments for multiple alloy compositions per experiment and the results are analyzed to yield activity values, phase transition temperatures, and partial molar entropies/enthalpies for each composition.

This protocol describes the measurement of the electromotive force of alkaline-earth elements in liquid metal alloys at high temperatures (723-1,123 K) to determine their thermodynamic properties, including activity, partial molar entropy, partial molar enthalpy, and phase transition temperatures, over a wide composition range.

用电动势技术测定碱土金属合金的热力学性质

A novel electrochemical cell based on a CaF2 solid-state electrolyte has been developed to measure the electromotive force (emf) of binary alkaline ...

Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

Here, we present a protocol for typical experiments of soft X-ray absorption spectroscopy (sXAS) and resonant inelastic X-ray scattering (RIXS) with applications in battery material studies.

软 x 射线吸收光谱和共振非弹性 x 射线散射法检测电池化学成分的元素敏感度

Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid ...

Novel Techniques for Observing Structural Dynamics of Photoresponsive Liquid Crystals

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational spectroscopy and time-resolved electron diffraction. Liquid crystal phase is an important state of matter that exists between the solid and liquid phases and it is common in natural systems as well as in organic electronics. Liquid crystals are orientationally ordered but loosely packed, and therefore, the internal conformations and alignments of the molecular components of LCs can be modified by external stimuli. Although advanced time-resolved diffraction techniques have revealed picosecond-scale molecular dynamics of single crystals and polycrystals, direct observations of packing structures and ultrafast dynamics of soft materials have been hampered by blurry diffraction patterns. Here, we report time-resolved IR vibrational spectroscopy and electron diffractometry to acquire ultrafast snapshots of a columnar LC material bearing a photoactive core moiety. Differential-detection analyses of the combination of time-resolved IR vibrational spectroscopy and electron diffraction are powerful tools for characterizing structures and photoinduced dynamics of soft materials.

Here, we present the protocols of differential-detection analyses of time-resolved infrared vibrational spectroscopy and electron diffraction which enable observations of the deformations of local structures around photoexcited molecules in a columnar liquid crystal, giving an atomic perspective on the relationship between the structure and the dynamics of this photoactive material.

观测 Photoresponsive 液晶结构动力学的新方法

We discuss in this article the experimental measurements of the molecules in liquid crystal (LC) phase using the time-resolved infrared (IR) vibrational ...

Using Graphene Liquid Cell Transmission Electron Microscopy to Study in Situ Nanocrystal Etching

Graphene liquid cell electron microscopy provides the ability to observe nanoscale chemical transformations and dynamics as the reactions are occurring in liquid environments. This manuscript describes the process for making graphene liquid cells through the example of graphene liquid cell transmission electron microscopy (TEM) experiments of gold nanocrystal etching. The protocol for making graphene liquid cells involves coating gold, holey-carbon TEM grids with chemical vapor deposition graphene and then using those graphene-coated grids to encapsulate liquid between two graphene surfaces. These pockets of liquid, with the nanomaterial of interest, are imaged in the electron microscope to see the dynamics of the nanoscale process, in this case the oxidative etching of gold nanorods. By controlling the electron beam dose rate, which modulates the etching species in the liquid cell, the underlying mechanisms of how atoms are removed from nanocrystals to form different facets and shapes can be better understood. Graphene liquid cell TEM has the advantages of high spatial resolution, compatibility with traditional TEM holders, and low start-up costs for research groups. Current limitations include delicate sample preparation, lack of flow capability, and reliance on electron beam-generated radiolysis products to induce reactions. With further development and control, graphene liquid cell may become a ubiquitous technique in nanomaterials and biology, and is already being used to study mechanisms governing growth, etching, and self-assembly processes of nanomaterials in liquid on the single particle level.