Charge-transfer interaction directed supramolecular assembly based on pyrene-modified polyoxometalate: From chiral induction to structural transformation

Abstract

Polyoxometalate (POM)-containing supramolecular assemblies possess multiply stimuli-responsiveness, and are important for developing intelligent materials. To date, though hydrogen bonding, host-guest interaction and coordination bond have been applied to construct hybrid assembly, it is still emergent to introduce more driving forces such as charge-transfer interaction, which can bring new structural and functional features. Herein, a pyrene-modified Anderson-type POM bearing sodium cations is synthesized, and possesses good solubility in water, which is used to combine with 1,2,4,5-tetracyanobenzene (TCNB). The prepared hybrid shows a one-dimensional hybrid structure via the charge-transfer interaction between pyrene and TCNB, which is verified by various technological measurements. By utilizing the attraction between polyanionic cluster and alkaline amino acid, l-/D-arginine can be imported into the system, resulting in the chiral induction of the hybrid assembly, which cannot be seen in each individual component. The emerging chirality in the supramolecular assemblies leads to the change of the morphology, and a transformation from chain to nanosheet and then tubular structure can be achieved accompanying distinct induced chirality signals. The present results develop a strategy for constructing POM-containing supramolecular assemblies based on the charge-transfer interaction, which morphologies can be modulated by some chiral species, showing potential applications in the field of soft and intelligent materials.