which allows their fluorescent sensing in the μM range. A new methodology for determination of anion binding constants to strongly acidic receptors by inhibitory effects of anions on the receptor deprotonation by an external base has been developed. High affinity and selectivity of anion complexation by dicationic pyridine-2,6-dicarboxamides is attributed to the rigid preorganized structure of receptors
在的三种异构体的
吡啶基或
喹啉基部分的衍
生物双阳离子N-甲基化Ñ,Ñ ' -双(
吡啶基)
吡啶-2,6-二甲酰胺(ø - ,米- ,和p - 1)和Ñ,Ñ N'-双(3-
喹啉基)
吡啶-2,6-二甲酰胺(4)在MeCN(日志强烈结合阴离子ķ在范围3.5-6.5)与
氯显着的选择性- ,并且还结合中性
脲和酰胺客人日志ķ范围1.1-2.8。m - 1,p - 1
三氟甲磺酸盐的晶体结构,和4显示酰胺NH和
吡啶鎓邻-CH基团被定向在受体裂缝内部,其四个质子形成半径为ca的圆。2.35最佳列入的Cl - 。阴离子的这些质子的结合从混合
三氟甲磺酸酯/
氯化物的盐的晶体结构是显而易见的p - 1,1计算(DFT / B3LYP 6-31G **)结构:有Cl所有受体的复合物1 - ,和1 H NMR滴定的结果。在o - 1
吡啶鎓N-Me +的晶体结构中这些基团被定向到受体的内部,阻止了阴离子的络合,但是计算结果表