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Chiral Self‐Discrimination and Guest Recognition in Helicene‐Based Coordination Cages
Author(s) -
Schulte Thorben R.,
Holstein Julian J.,
Clever Guido H.
Publication year - 2019
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201812926
Subject(s) - helicene , enantiopure drug , supramolecular chemistry , chemistry , enantioselective synthesis , chirality (physics) , ligand (biochemistry) , racemic mixture , molecular recognition , circular dichroism , stereochemistry , affinities , supramolecular chirality , crystallography , self assembly , combinatorial chemistry , enantiomer , organic chemistry , molecule , crystal structure , receptor , catalysis , biochemistry , nambu–jona lasinio model , physics , quantum mechanics , quark , chiral symmetry breaking
Chiral nanosized confinements play a major role for enantioselective recognition and reaction control in biological systems. Supramolecular self‐assembly gives access to artificial mimics with tunable sizes and properties. Herein, a new family of [Pd 2 L 4 ] coordination cages based on a chiral [6]helicene backbone is introduced. A racemic mixture of the bis‐monodentate pyridyl ligand L 1 selectively assembles with Pd II cations under chiral self‐discrimination to an achiral meso cage, cis ‐[Pd 2 L 1 P 2 L 1 M 2 ]. Enantiopure L 1 forms homochiral cages [Pd 2 L 1 P / M 4 ]. A longer derivative L 2 forms chiral cages [Pd 2 L 2 P / M 4 ] with larger cavities, which bind optical isomers of chiral guests with different affinities. Owing to its distinct chiroptical properties, this cage can distinguish non‐chiral guests of different lengths, as they were found to squeeze or elongate the cavity under modulation of the helical pitch of the helicenes. The CD spectroscopic results were supported by ion mobility mass spectrometry.