Toward a Single-Layer Two-Dimensional Honeycomb Supramolecular Organic Framework in Water
Kang-Da Zhang, Jia Tian, David Hanifi, Yuebiao Zhang, Andrew Chi-Hau Sue, Tian-You Zhou, Lei Zhang, Xin Zhao*, Yi Liu*, and Zhan-Ting Li*
J. Am. Chem. Soc.2013, 135, 17913–17918 (Highlighted as Front Cover)
The self-assembly of well-defined 2D supramolecular polymers in solution has been a challenge in supramolecular chemistry. We have designed and synthesized a rigid stacking-forbidden 1,3,5-triphenylbenzene compound that bears three 4,4′-bipyridin-1-ium (BP) units on the peripheral benzene rings. Three hydrophilic bis(2-hydroxyethyl)carbamoyl groups are introduced to the central benzene ring to suppress 1D stacking of the triangular backbone and to ensure solubility in water. Mixing the triangular preorganized molecule with cucurbituril (CB) in a 2:3 molar ratio in water leads to the formation of the first solution-phase single-layer 2D supramolecular organic framework, which is stabilized by the strong complexation of CB with two BP units of adjacent molecules. The periodic honeycomb 2D framework has been characterized by various 1H NMR spectroscopy, dynamic light scattering, X-ray diffraction and scattering, scanning probe and electron microscope techniques and by comparing with the self-assembled structures of the control systems.