Supramolecular Mechanoluminescence via Fluorine Interactions

Abstract

Mechanoluminescent (ML) materials, capable of converting mechanical stimuli directly into light emission without external excitation, hold great potential for use in sustainable optoelectronics and wearable technologies. However, the development of organic ML systems has long been limited by the trade-off among brightness, sensitivity, and mechanical durability. Here, we present a supramolecular assembly design that overcomes this trade-off by leveraging directional fluorine interactions, i.e., well-defined C─H···F─C hydrogen-bonds and the rarely reported L-geometry C─F···F─C contacts. The resulting supramolecular network stabilizes favorable molecular packing against mechanical damage while preserving optimal crystallinity, leading to bright and durable ML emission even during continuous mechanical grinding. Systematic structure-property analysis has successfully revealed the key design criteria for high-performance ML. We also establish a universal supramolecular platform that enables efficient Förster resonance energy transfer from the ML host to the ML-inactive luminophores across the visible spectrum (green, yellow, and red). Furthermore, the fabricated prototype supramolecular ML stress sensors exhibit remarkable sensitivity, with naked-eye-detectable ML at an ultralow impact force of 0.05 N. This work has put forward that fluorine-driven supramolecular assembly is a robust and versatile design strategy for advanced organic ML materials.

Keywords: Fluorine interactions; Mechanoluminescence; Structure‐property relationship; Supramolecular assembly.