Centro de Reconocimiento Molecular y Desarrollo Tecnológico (IDM), Unidad Mixta Universidad de Valencia-Universidad Politécnica de Valencia, Departamento de Química UPV, Camino de Vera s/n, 46022 Valencia, Spain.
Org Biomol Chem. 2012 Sep 28;10(36):7418-28. doi: 10.1039/c2ob26200b.
A family of heterocyclic thiosemicarbazone dyes (3a-f and 4) containing furyl groups was synthesized in good yields, characterized and their response in acetonitrile in the presence of selected anions was studied. Acetonitrile solutions of 3a-f and 4 showed absorption bands in the 335-396 nm range which are modulated by the electron donor or acceptor strength of the heterocyclic systems appended to the thiosemicarbazone moiety. Fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulphate, nitrate, acetate and cyanide anions were used in recognition studies. From these anions, only sensing features were seen for fluoride, cyanide, acetate and dihydrogen phosphate. Two clearly different chromo-fluorogenic behaviours were observed: (i) a small shift of the absorption band due to the coordination of the anions with the thiourea protons and (ii) the appearance of a new red shifted band due to deprotonation. For the latter effect, a change in the colour of solution from pale yellow to purple was observed. Fluorescence studies were also in agreement with the different effects observed in the UV/Vis titrations. In this case, hydrogen bonding interactions were visible through the enhancement of the emission band, whereas deprotonation induced the appearance of a new red-shifted emission. Logarithms of stability constants for the two processes (complex formation + deprotonation) for receptors in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec V1.1.18 program. Semi-empirical calculations to evaluate the hydrogen-donating ability of the receptors and a prospective electrochemical characterization of compound in the presence of fluoride were also performed.
一种含呋喃基团的杂环缩硫代氨基脲染料（3a-f 和 4）家族被很好地合成，具有特征，并研究了它们在乙腈中在选定阴离子存在下的响应。3a-f 和 4 的乙腈溶液在 335-396nm 范围内显示出吸收带，这些吸收带受附加到缩硫代氨基脲部分的杂环系统的供电子或受电子强度调制。在识别研究中使用了氟化物、氯化物、溴化物、碘化物、二氢磷酸盐、硫酸氢盐、硝酸盐、乙酸盐和氰化物阴离子。在这些阴离子中，只有氟化物、氰化物、乙酸盐和二氢磷酸盐表现出传感特征。观察到两种明显不同的显色-荧光行为：（i）由于阴离子与硫脲质子的配位导致吸收带发生小位移，（ii）由于去质子化而出现新的红移带。对于后一种效应，观察到溶液颜色从浅黄色变为紫色。荧光研究也与紫外/可见滴定中观察到的不同效应一致。在这种情况下，可以通过增强发射带观察到氢键相互作用，而去质子化则导致新的红移发射出现。在 HypSpec V1.1.18 程序中，使用分光光度滴定法确定了在氟化物和乙酸盐阴离子存在下受体的两个过程（络合+去质子化）的稳定性常数的对数。还进行了半经验计算以评估受体的供氢能力以及在存在氟化物的情况下化合物的预期电化学表征。
