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Dynamic Open Coordination Cage from Nonsymmetrical Imidazole–Pyridine Ditopic Ligands for Turn‐On/Off Anion Binding
Author(s) -
Ogata Daiji,
Yuasa Junpei
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.201911097
Subject(s) - chemistry , imidazole , cage , pyridine , ligand (biochemistry) , ion , crystallography , stoichiometry , stereochemistry , turn (biochemistry) , medicinal chemistry , receptor , organic chemistry , biochemistry , mathematics , combinatorics
This work demonstrates a new nonconventional ligand design, imidazole/pyridine‐based nonsymmetrical ditopic ligands ( 1 and 1 S ), to construct a dynamic open coordination cage from nonsymmetrical building blocks. Upon complex formation with Pd 2+ at a 1:4 molar ratio, 1 and 1 S initially form mononuclear PdL 4 complexes (Pd 2+ ( 1 ) 4 and Pd 2+ ( 1 S ) 4 ) without formation of a cage. The PdL 4 complexes undergo a stoichiometrically controlled structural transition to Pd 2 L 4 open cages ((Pd 2+ ) 2 ( 1 ) 4 and (Pd 2+ ) 2 ( 1 S ) 4 ) capable of anion binding, leading to turn‐on anion binding. The structural transitions between the Pd 2 L 4 open cage and the PdL 4 complex are reversible. Thus, stoichiometric addition (2 equiv) of free 1 S to the (Pd 2+ ) 2 ( 1 S ) 4 open cage holding a guest anion ((Pd 2+ ) 2 ( 1 S ) 4 ⋅G − ) enables the structural transition to the Pd 2+ ( 1 S ) 4 complex, which does not have a cage and thus causes the release of the guest anion (Pd 2+ ( 1 S ) 4 +G − ).