Crystal Engineering of a Chiral Crystalline Sponge That Enables Absolute Structure Determination and Enantiomeric Separation
Chenghua Deng, Bai‐Qiao Song, Matteo Lusi, Andrey A. Bezrukov, Molly M. Haskins, Mei‐Yan Gao, Yun‐Lei Peng, Jian‐Gong Ma, Peng Cheng, Soumya Mukherjee, Michael J. Zaworotko
Abstract
High Resolution Image Download MS PowerPoint Slide Chiral metal–organic materials (CMOMs), can offer molecular binding sites that mimic the enantioselectivity exhibited by biomolecules and are amenable to systematic fine-tuning of structure and properties. Herein, we report that the reaction of Ni(NO 3 ) 2, S -indoline-2-carboxylic acid ( S -IDECH), and 4,4′-bipyridine (bipy) afforded a homochiral cationic diamondoid, dia, network, [Ni( S -IDEC)(bipy)(H 2 O)][NO 3 ], CMOM-5 . Composed of rod building blocks (RBBs) cross-linked by bipy linkers, the activated form of CMOM-5 adapted its pore structure to bind four guest molecules, 1-phenyl-1-butanol (1P1B), 4-phenyl-2-butanol (4P2B), 1-(4-methoxyphenyl)ethanol (MPE), and methyl mandelate (MM), making it an example of a chiral crystalline sponge (CCS). Chiral resolution experiments revealed enantiomeric excess, ee, values of 36.2–93.5%. The structural adaptability of CMOM-5 enabled eight [email protected] CMOM-5 crystal structures to be determined. The five ordered crystal structures revealed that host–guest hydrogen-bonding interactions are behind the observed enantioselectivity, three of which represent the first crystal structures determined of the ambient liquids R -4P2B, S-4P2B, and R -MPE.