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Enantiopure Alleno‐Acetylenic Helicages Containing Multiple Binding Sites
Author(s) -
Gidron Ori,
Jirásek Michael,
Wörle Michael,
Diederich François
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201603923
Subject(s) - enantiopure drug , chemistry , zinc , circular dichroism , stereochemistry , allosteric regulation , molecule , allene , crystallography , receptor , catalysis , enantioselective synthesis , organic chemistry , biochemistry
Enantiopure alleno‐acetylenic ligands, containing two chiral allene moieties, assemble diastereoselectively with zinc(II) ions to form trinuclear triple‐stranded helicates, featuring two internal cavity binding sites (“helicages”). The addition of cycloalkanes or heteroalicycles results in inclusion complex formation with two guest molecules bound in one helicate. While no positive allosteric effects were observed, the chiroptical responses increased strongly upon complexation, with guest‐induced circular dichroism (ICD) signals reaching up to ΔΔ ϵ =205 m −1 cm −1 . The highest binding affinity was observed for six‐membered 1,4‐dichalcogens, with binding constants ( K 1 ) of up to 2400 m −1 for 1,4‐oxathiane in CD 3 OD. The X‐ray co‐crystal structure of 1,4‐dioxane bound to a dinuclear triple‐stranded helicate confirmed the previously predicted guest orientation inside the helicage, with the two oxygen atoms facing towards the electropositive zinc(II) metal centers.