Size-Selective Recognition by a Tubular Assembly of Phenylene–Pyrimidinylene Alternated Macrocycle through Hydrogen-Bonding Interactions

• Published in: Langmuir Vol. 31; no. 39; pp. 10649 - 10655
• Main Authors: Xiao, Duoduo, Zhang, Dengqing, Chen, Beihua, Xie, Dahai, Xiang, Yunjie, Li, Xianying, Jin, Wusong
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 06.10.2015
• Subjects: aromatic acids; chloroform; dimethyl sulfoxide; dissociation; encapsulation; fluorescence; Hydrogen Bonding; Macrocyclic Compounds - chemistry; methylene chloride; nanotubes; nuclear magnetic resonance spectroscopy; Proton Magnetic Resonance Spectroscopy; solvents; tetrahydrofuran; titration
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/acs.langmuir.5b02273

Study of artificial tubular assemblies as a useful host scaffold for size-selective recognition and release of guest molecules is an important subject in host–guest chemistry. We describe well-defined self-assembled nanotubes (NT 6mer ) formed from π-conjugated m-phenylene–pyrimidinylene alternated macrocycle 1 6mer that exhibit size-selective recognition toward a specific aromatic acid. In a series of guest molecules, a size-matched trimesic acid (G3) gives inclusion complexes (NT 6mer ⊃G3) in dichloromethane resulting in an enhanced and red-shifted fluorescence. 1H nuclear magnetic resonance (NMR) titration experiments indicated that the complex was formed in a 1:1 molar ratio. Density functional theory (DFT) calculations and the binding constant value (K = 1.499 × 105 M–1) of NT 6mer with G3 suggested that the complex involved triple hydrogen-bonding interactions. The encapsulated guest G3 molecules can be readily released from the tubular channel through the dissociation of hydrogen bonding by the addition of a polar solvent such as dimethylsulfoxide (DMSO). In contrast, 1 6mer could not form self-assembled nanotubes in CHCl3 or tetrahydrofuran (THF) solution, leading to weak or no size-selective recognizability, respectively.