Helical Self-Assembly-Induced Singlet–Triplet Emissive Switching in a Mechanically Sensitive System

Abstract

In nanoscience, chirality has shown a significant ability to tune materials' electronic properties, whereas imposing macrochirality into the regulation of singlet-triplet features of organic optoelectronics remains a challenging research topic. Since the tuning for singlet and triplet excited-state properties in a single π-functional molecule connects to its multicolor luminescent application and potential improvement of internal quantum efficiency, we here report that supramolecular chirality can be employed to toggle the singlet and triplet emissions in a well-designed asterisk-shaped molecule. Employing a hexathiobenzene-based single luminophore as a prototype and functionalizing it with chiral α-lipoiate side groups, we find that helical nanoarchitectures can accordingly form in mixed DMF/HO solution. On this basis, switching between fluorescence and phosphorescence of the material can be realized upon helical self-assembly and dissociation. Such a behavior can be attributed to a helical-conformation-dependent manipulation of the intersystem crossing. Furthermore, reversible mechanoluminescence of the corresponding solid sample was also observed to rely on an analogous molecular self-assembly alternation. These results can probably provide new visions for the development of next-generation supramolecular chiral functional materials.

Dynamic Modulation of Supramolecular Chirality Driven by Factors from Internal to External Levels

“…d) CD spectra of 1 in DMF/H 2 O. Reproduced with permission from Ref. . Copyright 2017, American Chemical Society.…”

Sequence and Structure of Peptoid Oligomers Can Tune the Photoluminescence of an Embedded Ruthenium Dye

“…[6] It was also demonstrated that the luminescence intensity of synthetic helicates, [7,8] aromatic foldamers, [9] peptides [10] and peptoids [11] containingc hromophores incorporated in their backbone, could be controlled by changing the chemical environment of the chromophore using solvophobic interactions, [9] pH, [11b] or binding of substrate molecules. [12] However,t he direct relationship between the conformationalo rder of peptidomimetics and ap hysical utility such as the luminescenceo fa ne mbedded metal complex, that does not involve changing its chemical environment, has not yet been reported. Linking together two fundamentalp roperties such as high-order structure and luminescence may provide fundamentali nsights on the relationship betweens tructure and function, and open new avenues for possible applications in photocatalysis, chemical biology,m olecular imaging and more.…”

Crystal Multi‐Conformational Control Through Deformable Carbon‐Sulfur Bond for Singlet‐Triplet Emissive Tuning

“…Multi-sulfurated aromatic compounds are prone to take effect metal-free room-temperature phosphorescence emitters in which the ISC process is environmentally adjustable. [35][36][37][38] Thec ompounds can be readily synthesized from low-cost precursors with different functional groups modified for postprocessing. [39][40][41] Herein, we designed and synthesized two fluoro-substituted tetrakis(arylthio)benzene molecules (compound 1 and 2,F igure 1), based on the anticipation that the multiple C À Sb ond can be deformable for tuning the molecular conformation with diverse intermolecular noncovalent interaction (e.g., CHÀFb ond, CH-p,S ÀSi nteraction, p-p stacking, etc.).…”