Chiral transcription in self-assembled tetrahedral Eu4L6 chiral cages displaying sizable circularly polarized luminescence

• DOI: 10.1038/s41467-017-01025-1
• Publication Date: 2017-10-18T20:49:56Z
• Authors: Chi-Tung Yeung; King-Him Yim; Ho-Yin Wong; Robert Pal; Wai-Sum Lo; Siu-Cheong Yan; Melody Yee-Man Wong; Dmitry Yufit; Danil E. Smiles; Laura J. McCormick; Simon J. Teat; David K. Shuh; Wing-Tak Wong; Ga-Lai Law
• Keywords: Science; Organic Chemistry; Q; 540; 530; 01 natural sciences; Article; Macromolecular and Materials Chemistry; 0104 chemical sciences; Inorganic Chemistry; 539; Chemical Sciences

AbstractPredictable stereoselective formation of supramolecular assembly is generally believed to be an important but complicated process. Here, we show that point chirality of a ligand decisively influences its supramolecular assembly behavior. We designed three closely related chiral ligands with different point chiralities, and observe their self-assembly into europium (Eu) tetrametallic tetrahedral cages. One ligand exhibits a highly diastereoselective assembly into homochiral (either ΔΔΔΔ or ΛΛΛΛ) Eu tetrahedral cages whereas the two other ligands, with two different approaches of loosened point chirality, lead to a significant breakdown of the diastereoselectivity to generate a mixture of (ΔΔΔΔ and ΛΛΛΛ) isomers. The cages are highly emissive (luminescence quantum yields of 16(1) to 18(1)%) and exhibit impressive circularly polarized luminescence properties (|glum|: up to 0.16). With in-depth studies, we present an example that correlates the nonlinear enhancement of the chiroptical response to the nonlinearity dependence on point chirality.