Water soluble sapphyrins: potential fluorescent phosphate anion sensors.
Water soluble sapphyrins: potential fluorescent phosphate anion sensors.
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DOI：
10.1039/b306964h
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发表时间：
2003-11
影响因子：
3.2
通讯作者：
J. Sessler;Julian M. Davis;V. Král;Thomas J Kimbrough;V. Lynch
中科院分区：
文献类型：
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作者：
J. Sessler;Julian M. Davis;V. Král;Thomas J Kimbrough;V. Lynch
作为一个正在进行的努力，以研究在各种介质中的阴离子结合性能的sapphyrin的一部分，一些先前报道的水溶性sapphyrin在甲醇和缓冲，中性水溶液中进行了研究，发现在这些溶液相条件下进行自聚集。通过紫外-可见吸收光谱和荧光光谱研究了作为自聚集的结果产生的物种的性质和导致其形成的过程。在以前的工作（V. Král，H。Furuta，K. Shreder，V. Lynch，and J. L. Sessler，J. Am. 1996，118 1595-1607），发现在pH 6.1下将磷酸盐型阴离子加入到水溶性卟啉中引起可见光谱变化，这与结合到聚集形式和同时形成有效平衡常数为100-300 M（-1）数量级的阴离子结合的二聚体一致。在这项研究中，我们表明，在中性，缓冲水溶液中，在高磷酸盐卟啉比进一步解聚发生产生阴离子结合的单体形式。这种高度荧光的物种形成的有效平衡常数为6-19 M（-1）的数量级，导致的考虑，sapphyrin可以作为荧光磷酸根阴离子传感器。在努力调节的解聚性能，几个新的sapphyrin衍生物轴承两个meso芳基取代基的制备和研究。这些后者系统的聚集特性进行了分析，在甲醇中，在一个水溶性系统的情况下，在中性水介质中。与对β-烷基取代的卟啉所观察到的类似，在水介质中的水溶性内消旋取代体系中观察到H型聚集体。然而，在相反的H-型二聚体的情况下看到的内消旋系统在甲醇中，J-型二聚体的情况下观察到的sapphyrin轴承两个内消旋取代基在这种溶剂中。的有效二聚常数的meso-diaryl sapphyrins的几个在甲醇中被确定为在水介质中的pKa值。还测定了一种内消旋-二芳基卟啉，特别是10，15-双（3，5-二叔丁基苯基）-3，22-二乙基-2，23-二甲基卟啉的双HBr盐的固态结构，发现其显示出与先前报道的卟啉衍生物相同的元素。特别是，两个抗衡阴离子被发现是氢结合的上方和下方的双质子化sapphyrin平面。
As part of an ongoing effort to study the anion binding properties of sapphyrins in various media, a number of previously reported water solubilized sapphyrins were studied in methanol and in buffered, neutral aqueous solutions and found to undergo self-aggregation under these solution phase conditions. The nature of the species produced as the result of self-aggregation and the processes leading to their formation were studied via UV-vis absorbance and fluorescence spectroscopy. In previous work (V. Král, H. Furuta, K. Shreder, V. Lynch, and J. L. Sessler, J. Am. Chem. Soc. 1996, 118 1595-1607) it was found that the addition of phosphate-type anions to water soluble sapphyrins at pH 6.1 gives rise to visible spectroscopic changes consistent with the binding to the aggregated form and the concurrent formation of an anion-bound dimer with effective equilibrium constants on the order of 100-300 M(-1). In this study we show that at high phosphate-to-sapphyrin ratios in neutral, buffered aqueous solutions further deaggregation occurs to produce an anion-bound monomeric form. This highly fluorescent species is formed with effective equilibrium constants on the order of 6-19 M(-1) leading to considerations that sapphyrins could function as fluorescent phosphate anion sensors. In an effort to modulate the deaggregation properties, several new sapphyrin derivatives bearing two meso aryl substituents were prepared and studied. The aggregation properties of these latter systems were analyzed in methanol and, in the case of one water solublized system, in neutral aqueous media. In analogy to what was observed for the beta-alkyl substituted sapphyrins, H-type aggregates were seen for the water solubilized meso-substituted system in aqueous media. However, in contrast to the H-type dimers seen in the case of the meso-free systems in methanol, J-type dimers were observed in the case of the sapphyrins bearing two meso substituents in this solvent. The effective dimerization constants of several of the meso-diaryl sapphyrins were determined in methanol as were their pKa values in aqueous media. The solid state structure of the bis HBr salt of one of the meso-diaryl sapphyrins, specifically 10,15-bis(3,5-di-tert-butylphenyl)-3,22-diethyl-2,23-dimethylsapphyrin, was also determined and found to show elements in common with those of previously reported sapphyrin derivatives. In particular, the two counter anions were found to be hydrogen bound above and below the diprotonated sapphyrin plane.