Eu <sup>3+</sup> ‐Directed Supramolecular Metallogels with Reversible Quadruple‐Stimuli Response Behaviors
Yan Chen, Huimin Li, Yakun Zhang, Zhiqiang Li, Daqing Yang
Abstract
Abstract Smart luminescent materials that have the ability to reversibly adapt to external environmental stimuli and possess a wide range of responses are continually emerging, which place higher demands on the means of regulation and response sites. Here, europium ions (Eu 3+ )‐directed supramolecular metallogels are constructed by orthogonal self‐assembly of Eu 3+ based coordination interactions and hydrogen bonding. A new organic ligand ( L ) is synthesized, consisting of crown ethers and two flexible amide bonds‐linked 1,10‐phenanthroline moieties to coordinate with Eu 3+ . Synergistic intermolecular hydrogen bonding in L and Eu 3+ ‐ L coordination bonding enable Eu 3+ and L to self‐assemble into shape‐persistent 3D coordination metallogels in MeOH solution. The key to success is the utilization of crown ethers, playing dual roles of acting both as building blocks to build L with C 2 ‐symmetrical structure, and as the ideal monomer for increasing the energy transfer from L to Eu 3+ ’s excited state, thus maintaining the excellent luminescence of metallogels. Interestingly, such assemblies show K + , pH, F − , and mechano‐induced reversible gel‐sol transitions and tunable luminescence properties. Above findings are useful in the studies of molecular switches, dynamic assemblies, and smart luminescent materials.