Selectivity and Cooperativity in the Binding of Multiple Guests to a Pillar[5]arene–Crown Ether Fused Tricyclic Host

• Published in: Journal of organic chemistry Vol. 80; no. 16; pp. 7994 - 8000
• Main Authors: Hu, Wei-Bo, Xie, Chang-Dong, Hu, Wen-Jing, Zhao, Xiao-Li, Liu, Yahu A, Huo, Ji-Chuan, Li, Jiu-Sheng, Jiang, Biao, Wen, Ke
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 21.08.2015; Amer Chemical Soc
• Subjects: Binding Sites; Chemistry; Chemistry, Organic; Crown Ethers - chemistry; Crystallography, X-Ray; Macrocyclic Compounds - chemical synthesis; Macrocyclic Compounds - chemistry; Models, Molecular; Molecular Conformation; Physical Sciences; Quaternary Ammonium Compounds - chemistry; Science & Technology; HEMOGLOBIN; TOBACCO-MOSAIC-VIRUS; NOBEL LECTURE; PROTEIN; MOLECULAR RECOGNITION; PILLARENES; PORPHYRIN; PARAQUAT; COMPLEXATION; DERIVATIVES
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/acs.joc.5b01038

A novel tricylic host molecule 1 that consists of two pillar[5]­arene units and a crown ether ring was found to selectively bind two kinds of guest molecules with different shapes, sizes, and electronic constitutions, namely 1,4-dicyanobutane G1 and paraquat G2, with its two macrocyclic subunits, to form a four-component complex 2G1⊂1⊃G2. An 1H NMR study of stepwise bindings of G1 and G2 to host 1 in CDCl3/DMSO-d 6 revealed that the strength of the association between complex 2G1⊂1 and guest G2 was only one-fourth of that between free 1 and G2, demonstrating a negative heterotropic cooperativity of G1 in the binding of G2 to host 1.