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A Long‐Lived Halogen‐Bonding Anion Triple Helicate Accommodates Rapid Guest Exchange
Author(s) -
Massena Casey J.,
Decato Daniel A.,
Berryman Orion B.
Publication year - 2018
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.201810415
Subject(s) - chemistry , bromide , iodide , halogen bond , halide , ion , halogen , ligand (biochemistry) , self assembly , combinatorial chemistry , crystallography , photochemistry , polymer chemistry , inorganic chemistry , organic chemistry , biochemistry , alkyl , receptor
Abstract Anion‐templated helical structures are emerging as a dynamic and tractable class of supramolecules that exhibit anion‐switchable self‐assembly. We present the first kinetic studies of an anion helicate by utilizing halogen‐bonding m ‐arylene‐ethynylene oligomers. These ligands formed high‐fidelity triple helicates in solution with surprisingly long lifetimes on the order of seconds even at elevated temperatures. We propose an associative ligand‐exchange mechanism that proceeded slowly on the same timescale. In contrast, intrachannel anion exchange occurred rapidly within milliseconds or faster as determined by stopped‐flow visible spectroscopy. Additionally, the helicate accommodated bromide in solution and the solid state, while the thermodynamic stability of the triplex favored larger halide ions (bromide≈iodide≫chloride). Taken together, we elucidate a new class of kinetically stable helicates. These anion‐switchable triplexes maintain their architectures while accommodating fast intrachannel guest exchange.