作者:Wing-Yan Wong、Siu-Fung Lee、Hoi-Shan Chan、Thomas C. W. Mak、Chi-Hin Wong、Lau-Shan Huang、J. Fraser Stoddart、Ken Cham-Fai Leung
DOI:10.1039/c3ra43470b
日期:——
A series of 2,6-bis(imino)pyridyl-based V-shaped compounds bearing various para-substituents on the terminal aromatic rings [C5H3N(CHN–C6H4R)2; R = OMe, iPr, Me, H, Cl, F, and CF3] have been prepared and investigated for their reversible binding with the dumbbell-shaped cations NH2+–CH2–C6H3(OMe-3,5)2}2 and 9-anthryl–CH2–NH2+–CH2–C6H3(OMe-3,5)2. Three crystalline V-shaped compounds and a dumbbell hexafluorophosphate were characterised in the solid state by X-ray structural analysis. The binding mode of the 1 : 1 V-shaped molecule·dumbbell complexes was evaluated by 1H NMR spectroscopy. The binding constants (90–400 M−1 in dichloromethane) and stoichiometries of the complexes were determined using the Method of Continuous Variations and the Rose-Drago Method based on 1H NMR spectroscopic data. In a series of V-shaped compounds, the binding strength with both dumbbell cations diminishes with the decreasing electron-donating ability of the R substituents. Specifically, one of the diimine V-shaped compounds shows a stronger binding with the symmetrical dumbbell than with the unsymmetrical anthracene-containing dumbbell. Fluorescence measurements of equimolar mixtures of the V-shaped compounds and the unsymmetrical dumbbell have revealed a reduced anthracene emission which is approximately 50% that of the original intensity. Rapid and complete dissociation (<5 min) of the V-shaped compounds from the dumbbells was realised using an excess of acid or base, whereas only partial dissociation of the complexes was achieved with a large excess of water (<1 h).
我们制备了一系列 2,6-双(亚氨基)吡啶基 V 型化合物,其末端芳香环上带有各种对位取代基 [C5H3N(CHN-C6H4R)2;R = OMe、iPr、Me、H、Cl、F 和 CF3],并研究了它们与哑铃形阳离子 NH2+-CH2-C6H3(OMe-3,5)2}2 和 9-anthryl-CH2-NH2+-CH2-C6H3(OMe-3,5)2 的可逆结合。通过 X 射线结构分析,确定了三种 V 形结晶化合物和一种哑铃状六氟磷酸盐的固态特征。1 :通过 1H NMR 光谱评估了 1 : 1 V 型分子-哑铃复合物的结合模式。根据 1H NMR 光谱数据,采用连续变化法和 Rose-Drago 法确定了复合物的结合常数(二氯甲烷中为 90-400 M-1)和化学计量数。在一系列 V 型化合物中,与哑铃阳离子的结合强度随着 R 取代基电子负载能力的降低而减弱。具体来说,其中一种二亚胺 V 型化合物与对称哑铃的结合力强于与不对称含蒽哑铃的结合力。对 V 型化合物和非对称哑铃的等摩尔混合物进行的荧光测量显示,蒽的发射强度降低了约 50%。使用过量的酸或碱可实现 V 型化合物与哑铃的快速完全解离(小于 5 分钟),而使用大量过量的水(小于 1 小时)只能实现复合物的部分解离。