Drum-like Metallacages with Size-Dependent Fluorescence: Exploring the Photophysics of Tetraphenylethylene under Locked Conformations

Abstract

Materials with aggregation-induced emission (AIE) properties are of growing interest due to their widespread applications. AIEgens, such as tetraphenylethylene units, display varying emission behaviors during their conformational changes. However, the structure–property relationships of the intermediate conformations have rarely been explored. Herein, we show that the conformational restriction on TPE units can affect the structural relaxation in the excited state and the resulting photophysical behaviors. Specifically, three metallacages of different sizes were prepared via the coordination-driven self-assembly of a TPE-based tetrapyridyl donor with length-increasing Pt­(II) acceptors. While the metallacages share similar scaffolds, they exhibit a trend of red-shifted fluorescence and attenuated quantum yield with the increase of their sizes. Furthermore, spectroscopic and computational studies together with a control experiment were conducted, revealing that the degree of cage tension imposed on the excited-state conformational relaxation of TPE moieties resulted in their distinct photophysical properties. The precise control of conformation holds promise as a strategy for understanding the AIE mechanism as well as optimizing the photophysical behaviors of materials on the platform of supramolecular coordination complexes.

Multi‐Decker Emissive Supramolecular Architectures Based on Shape‐Complementary Ligands Pair

“…This result indicated that the double‐decker SD with a rigid backbone might effectively suppress the energy loss via a non‐radiative transition process by restricting the intramolecular rotation or vibration of TPE moieties. [ 29 ] Interestingly, although the triple‐decker assemblies E‐ST, Z‐ST, and G‐ST comprise a higher number of TPE primitives, the phenyl groups of TPE without tpy substitution could slightly undergo rotation. Hence, these triple‐decker complexes showed a weaker emission than that of double‐decker SD.…”

Dynamic Full‐Color Tuning of Organic Chromophore in a Multi‐Stimuli‐Responsive 2D Flexible MOF

“…Although most of the organic chromophores with nonplanar propeller geometry possess potential stimuliresponsiveness, [50] their luminescence responses in bulk states are weak or even imperceptible, mainly ascribed to the packing-induced rigidified molecular geometry and alignment. [25,51] In this work, given the coupled structural transformations of a 2D dynamic coordination space and the embedded chromophore, we then anticipated that this novel material may exhibit distinctive stimuli-responsive luminescent properties, with the hope of surpassing other types of smart luminescent materials.…”

Underwater luminescent labeling materials constructed from a supramolecular approach

“…COMMUNICATION aggregation-induced emission (AIE) properties ideally meet solid-state luminescent material requirements. [31][32][33][34][35] Herein, a supramolecular approach combining noncovalent copolymerization and fluorescence emission was used to construct underwater labeling materials. Bulk adhesives with strong adhesion capacity and luminescent behavior were designed and fabricated.…”