Spontaneous colorimetric sensing of the positional isomers of dihydroxynaphthalene in a 1D organogel matrix
Spontaneous colorimetric sensing of the positional isomers of dihydroxynaphthalene in a 1D organogel matrix
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DOI：
10.1002/anie.200503158
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发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Shinkai, S
中科院分区：
文献类型：
--
作者：
Mukhopadhyay, P;Iwashita, Y;Shinkai, S
最近对功能性和刺激反应性有机凝胶的兴趣高涨，揭示了迄今为止在溶液和固态中未知的分子的新的和令人兴奋的性质迄今为止，酰胺、尿素和糖基团之间的氢键相互作用以及胆固醇基团之间的范德华相互作用主要用于构建适合凝胶化的一维（1D）结构。相比之下，利用π- π-堆积相互作用形成1D低分子量凝胶的相对较新的设计策略的例子相当有限。[3a-d]我们利用这一概念生产了具有光捕获特性的一维苝酰亚胺基有机凝胶。[3e， f]我们对开发具有识别特性的一维萘二亚胺基有机凝胶的兴趣是由以下动机驱动的：首先，萘二亚胺是一种具有扩展π表面的多用途分子[4]，已被应用于导电材料、人工光合系统以及DNA插层器的设计中。其次，萘二酰亚胺-烷氧炔体系是一种重要的超分子基序，已被应用于大量新结构的设计中：例如，Sanders、Stoddart和同事已经报道了[2]链烷、[2]轮烷和伪[2]轮烷，Iverson和同事已经设计了折叠的aedamer——基于这种多功能的供体-受体相互作用的人工双链化合物。然而，令人惊讶的是，这一重要的基序至今尚未在有机凝胶系统中得到研究。在这里，我们提出了一种高效，通用的有机凝胶(1)，它形成了一个强大的一维凝胶上层结构。我们合理地设想，1的凝胶基质将与1,5 -二氧萘环结合，遵循由萘二酰亚胺-烷氧萘环基序衍生的超分子结构的先例然而，令我们惊讶的是，有机凝胶1不与这个众所周知的互补伙伴相互作用，相反，它表现出对极性亲水性二羟基萘的选择性识别。因此，我们偶然发现了一种替代的超分子结合基序，它主要只在凝胶状态下起作用。我们利用这种不寻常的识别模式和凝胶相环境中显著放大的结合来设计一个简单直接的比色检测系统。利用该系统，可以用肉眼清楚地区分二羟基萘的几种位置异构体；这种过程在常规溶液状态下是不可能进行的。据我们所知，这是在比色传感系统中使用有机凝胶基质的第一个例子。凝胶分子1被设计成包含π -π堆叠、h键和范德华力的组合。我们预计萘二酰亚胺部分会促进一维上层结构的形成，因为它倾向于形成π堆叠结构。有趣的是，我被发现是一个多才多艺的gelator；它在26种常用有机溶剂中的19种中形成稳定的凝胶该凝胶表现出可逆的溶胶-凝胶转变，并且温度相关的光谱变化强烈表明凝胶中存在π - π堆叠的萘二亚胺单元，这些单元在加热时解堆叠（见支持信息）。由1构建的一维形貌通过透射电镜观察得到证实（见支持信息）。为了研究[7]在凝胶基质1中的识别特性，我们首先选择1,5 -二甲氧基萘（4a）作为底物，因为已知它与…
The recent upsurge of interest in functional and stimuliresponsive organogels [1] has unraveled new and exciting properties of molecules hitherto unknown in solution and the solid state.[2] Hydrogen-bonding interactions between amide, urea, and sugar groups as well as the van der Waals interactions between cholesteryl groups have chiefly been utilized so far in the construction of onedimensional (1D) architectures suitable for gelation. In contrast, examples of a relatively new design strategy that utilizes the π–π-stacking interaction to form 1D low-molecular-weight gels are rather limited.[3a–d] We employed this concept to produce 1D perylenediimide-based organogels with light-harvesting properties.[3e, f] Our interest in the development of a 1D naphthalenediimide-based organogel that exhibits recognition properties was driven by the following motives: Firstly, naphthalenediimide is a versatile molecule [4] with an extended π surface and has been applied in the design of conductive materials, artificial photosynthetic systems, as well as DNA intercalators. Secondly, the naphthalenediimide–alkoxynaphthalene system is an important supramolecular motif that has been applied in the design of a plethora of novel architectures:[5] for example, Sanders, Stoddart, and co-workers have reported [2] catenanes,[2] rotaxanes, and pseudo [2] rotaxanes, and Iverson and coworkers have designed folded aedamers—artificial duplexes based on this versatile donor–acceptor interaction. Surprisingly, however, this important motif has not been investigated in an organogel system to date. Herein we present a highly efficient, versatile organogelator (1) that forms a robust 1D gel superstructure. We reasonably envisioned that the gel matrix of 1 would bind to 1, 5-dialkoxynaphthalenes following the precedent of supramolecular architectures derived from the naphthalenediimide–alkoxynaphthalene motif.[5] However, to our astonishment, organogel 1 does not interact with this well-known complementary partner, whereas it shows selective recognition of the polar, hydrophilic dihydroxynaphthalenes. Thus, we have found serendipitously an alternative supramolecular binding motif that predominantly operates only in the gel state. We utilized this unusual recognition pattern and the remarkably amplified binding in the gel-phase environment to design a simple and straightforward colorimetric detection system. With this system, it is possible to distinguish clearly several positional isomers of dihydroxynaphthalenes with the naked eye; such a process is impossible to carry out in the conventional solution state. To our knowledge, this is the first example of an organogel matrix that has been employed in a colorimetric sensing system.The gelator molecule 1 was designed to include a combination of π–π stacking, H-bonding, and van der Waals forces. We anticipated that the naphthalenediimide moiety would facilitate the formation of a 1D superstructure because of its propensity to form π-stacked structures. Interestingly, 1 was found to be a versatile gelator; it formed stable gels in 19 of the 26 common organic solvents evaluated.[6] This gel shows a reversible sol–gel transition, and the temperature-dependent spectral changes strongly indicate the existence of π–πstacked naphthalenediimide units in the gel which unstack upon heating (see Supporting Information). The 1D morphology constructed from 1 was confirmed by TEM observations (see Supporting Information). To investigate the recognition characteristics [7] in the gel matrix of 1, we first chose 1, 5-dimethoxynaphthalene (4a) as a substrate as it is known to form a strong donor–acceptor complex with …