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Updated: Nov 15, 2025
Synthesis of a Water-soluble Metal–Organic Complex Array
Published on: October 8, 2016
Multi-stimuli Control over Assembly and Guest Binding in Metallo-supramolecular Hosts Based on Dithienylethene
Ru-Jin Li1, Jacopo Tessarolo1, Haeri Lee1
1Faculty of Chemistry & Chemical Biology, TU Dortmund University, Otto-Hahn-Straße 6, 44227 Dortmund, Germany.
Abstract:
It is difficult to assemble multi-component metallo-supramolecular architectures in a non-statistical fashion, which limits their development toward functional materials. Herein, we report a system of interconverting bowls and cages that are able to respond to various selective stimuli (light, ligands, anions), based on the self-assembly of a photochromic dithienylethene (DTE) ligand, L, with PdII cations. By combining the concept of "coordination sphere engineering", relying on bulky quinoline donors, with reversible photoswitching between the ligand's open (o-L) and closed (c-L) forms, a [Pd2(o-L)4] cage (o-C) and a [Pd2(c-L)3] bowl (c-B) were obtained, respectively. This structural rearrangement modulates the system's guest uptake capabilities. Among three bis-sulfonate guests (G1, G2, and G3), the cage can encapsulate only the smallest (G1), while the bowl binds all of them. Bowl c-B was further used to synthesize a series of heteroleptic cages, [Pd2LA3LB], representing a motif never reported before. Additional ligands (L), with short or long arms, tune the cavity size, thus enabling or preventing guest uptake. Addition of Br-/Ag+ makes it possible to change the overall charge, again triggering guest uptake and release, as well as fourth ligand de-/recomplexation. In combination, site-selective introduction of functionality and application of external stimuli lead to an intricate system of hosts with different guest preferences. A high degree of complexity is achieved through cooperativity between only a few components.
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