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

doi:10.1021/acs.cgd.3c00446

Crystal Engineering of a Chiral Crystalline Sponge That Enables Absolute Structure Determination and Enantiomeric Separation

Cryst Growth Des. 2023 May 16;23(7):5211-5220. doi: 10.1021/acs.cgd.3c00446. eCollection 2023 Jul 5.

Authors

Affiliations

¹ Bernal Institute, Department of Chemical Sciences, University of Limerick, Limerick V94 T9PX, Ireland.
² Department of Chemistry and Key Laboratory of Advanced Energy Material Chemistry, College of Chemistry, Nankai University, Tianjin 300071, China.

Abstract

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(NO₃)₂, S-indoline-2-carboxylic acid (S-IDECH), and 4,4'-bipyridine (bipy) afforded a homochiral cationic diamondoid, dia, network, [Ni(S-IDEC)(bipy)(H₂O)][NO₃], 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 enantiomer@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.