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首页> 外文期刊>Chemistry: A European journal >Micelles for the self-assembly of 'off-on-off' fluorescent sensors for pH windows
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Micelles for the self-assembly of 'off-on-off' fluorescent sensors for pH windows

机译：自组装用于pH窗的“ off-on-off”荧光传感器的胶束

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摘要

A micellar approach is proposed to build a series of systems featuring an '' off-on-off '' fluorescent window response with changes in pH. The solubilizing properties of micelles are used to self-assemble, in water, plain pyrene with lipophilized pyridine and tertiary amine moieties. Since these components are contained in the small volume of the same micelle, pyrene fluorescence is influenced by the basic moieties: protonated pyridines and free tertiary amines behave as quenchers. Accordingly, fluorescence transitions from the '' off '' to the '' on '' state, and viceversa, take place when the pH crosses the pK(a) values of the amine and pyridine fragments. To obtain an '' off-on-off '' fluorescent response in this investigation we use either a set of dibasic lipophilic molecules (containing covalently linked pyridine and tertiary amine groups) or combinations of separate, lipophilic pyridines and tertiary amines. The use of combinations of dibasic and monobasic lipophilic molecules also gives a window-shaped fluorescence response with changes in pH: it is the highest pyridine pK(a) and the lowest tertiary amine pK(a) that determine the window limits. The pK(a) values of all the examined lipophilic molecules were determined in micelles, and compared with the values found for the same molecules in solvent mixtures in which they are molecularly dispersed. The effect of micellization is to significantly lower the observed protonation constants of the lipophilized species. Moreover, the more lipophilic a molecule is, the lower the observed logK value is. Accordingly changing the substituents on the basic moieties or modifying their structure, tuning the lipophilicity of the mono- or dibases, and choosing among a large set of possible combination of lipophilized mono- and dibases have allowed us to tune, almost at will, both the width and the position along the pH axis of the obtained fluorescent window.
机译：提出了一种胶束方法来构建一系列系统，这些系统具有随pH值变化的“开-关-关”荧光窗响应。胶束的增溶性能用于在水中自组装plain与亲脂的吡啶和叔胺基团。由于这些组分都包含在同一胶束的小体积中，因此fluorescence的荧光受碱性部分的影响：质子化吡啶和游离叔胺起猝灭剂的作用。因此，当pH值超过胺和吡啶片段的pK（a）值时，就会发生从“关闭”状态到“开启”状态的荧光转变，反之亦然。为了在这项研究中获得“开-关-关”的荧光响应，我们使用一组二元亲脂性分子（包含共价连接的吡啶和叔胺基）或单独的亲脂性吡啶和叔胺的组合。使用二元和一元亲脂性分子的组合还会产生随pH变化的窗口形荧光响应：决定窗口范围的是最高的吡啶pK（a）和最低的叔胺pK（a）。在胶束中测定所有检查的亲脂性分子的pK（a）值，并将其与分子分散在溶剂混合物中的相同分子的值进行比较。胶束化作用显着降低了亲脂化物质的观察到的质子化常数。而且，亲脂性分子越多，观察到的logK值越低。因此，改变基本部分上的取代基或改变其结构，调节单碱基或双碱基的亲脂性，以及在一大组可能的亲脂化单碱基和二碱基的组合中进行选择，使我们几乎可以随意调整两者的亲和力。宽度和所得荧光窗沿pH轴的位置。

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