双吲哚烯类受体对氨基酸的比色识别作用

Selective Colorimetric Recognition Properties of the Bis(indolyl)methene Receptors for Amino Acids

设计合成了一系列3,3'-双吲哚烯类受体分子,应用紫外-可见吸收光谱研究了该类受体对20种天然氨基酸分子的识别作用.结果表明,在乙腈-水溶液中,双吲哚烯受体分子可以通过其氢键受体位点的质子化作用比色识别天冬氨酸及谷氨酸等酸性氨基酸;而硝基取代的双吲哚烯受体分子则通过其氢键供体位点的去质子化作用比色识别精氨酸和赖氨酸等碱性氨基酸.在乙腈-水的中性缓冲溶液体系中,硝基取代的双吲哚烯类受体分子通过与巯基发生亲核加成反应,高选择性地比色识别半胱氨酸和同型半胱氨酸.

The development of artificial receptors for the selective recognition of biologically important species has been one of the best concerned topic in the field of supramolecular chemistry.The effective and selective molecular recognition or sensing of unprotected amino acids in aqueous solution is still a challenging problem due to their highly hydrophilic character.In this paper,a series of 3,3′-bis（indolyl）methene receptors was designed and synthesized,and the recognition properties of the receptors for 20 natural amino acids were stu-died via UV-Vis spectroscopic techniques.The result indicated that the receptors exhibited selective colorimetric sensing for amino acids by protonated/deprotonated process of the hydrogen bond site of the receptors in CH3CN/H2O（1∶1,volume ratio）.The introduction of methoxy group into indole ring,which increased the basicity of the hydrogen bond acceptor unit,can promote the occurrence of the protonated process and increase the sensing sensitivity for acidic amino acids.The receptors with nitro group exhibited obviously colorimetric sensing for basic amino acids（arginine,lysine） due to the deprotonation of the hydrogen bond donor unit of receptors.In CH3CN/H2O（1∶1,volume ratio;0.01 mol/L HEPES,pH=7.4） neutral buffered solution,the receptors without nitro group showed negligible spectral responses for various amino acids,but the nitro-substituted receptors exhibited high selective colorimetric sensing for cysteine（Cys） and homocysteine（Hcy） based on the nucleophilic addition reaction between the sulphydryl group of Cys/Hcy and the meso carbon-carbon double bond of receptors,leading to clear color change from yellow to colorless.