Lighting up solid states using a rubber

Abstract

It is crucial and desirable to develop green and high-efficient strategies to regulate solid-state structures and their related material properties. However, relative to solution, it is more difficult to break and generate chemical bonds in solid states. In this work, a rubbing-induced photoluminescence on the solid states of ortho-pyridinil phenol family was achieved. This rubbing response relied on an accurately designed topochemical tautomerism, where a negative charge, exactly provided by the triboelectric effect of a rubber, can induce a proton transfer in a double H-bonded dimeric structure. This process instantaneously led to a bright-form tautomer that can be stabilized in the solid-state settings, leading to an up to over 450-fold increase of the fluorescent quantum yield of the materials. The property can be repeatedly used due to the reversibility of the tautomerism, enabling encrypted applications. Moreover, a further modification to the structure can be accomplished to achieve different properties, opening up more possibilities for the design of new-generation smart materials.

Gel Materials with Rubber‐Rubbing‐Chromic Luminescence: A Portable Tool for On‐Spot Composing Highly Encrypted Information

“…[ 14 ] The generated hydrogen bonds led to the decrease in the bandgap of DPP and the redshift of the emission. [ 10 ] Furthermore, the peaks at 2917 and 2846 cm −1 remain the same, which means that the packing mode of alkyl chains are unchanged.…”

“…The deprotonated phenol structure in DPP caused the increase in bandgap and the blueshift of the emission. [ 10 ]…”

“…The deprotonated phenol structure in DPP caused the increase in bandgap and the blueshift of the emission. [10] Because the shifted fluorescence (green color) originated from the proton transferred anion species of DPP, [10] a reference system was prepared by adding an appropriate amount of organic base, trimethylamine, into DPP-LGG supramolecular gel to construct the deprotonated structure of DPP molecules. The fluorescence of the reference system is identical to the supramolecular gel after rubbing (Figure S18, Supporting Information), which further demonstrates the proposed hypothesis.…”

“…Through its own molecular packing, DPP is prone to undergo a topochemical tautomerization in its crystal form, rather than in solution. [ 10 ] Inspired by this fact, we expect to establish a topochemical condition at the gel level, by taking the ordered multiple H‐bonded network formed between DPP and gelators upon coassembly, which may facilitate a proton transferred tautomerization through the micelles, caused by the special triboelectric effect of rubber rubbing. Along with the π‐skeleton push–pull system design of DPP, a rubber‐rubbing‐chromic luminescence is also anticipated by tuning.…”

Thermal Energy-Driven Solid-State Molecular Rotation Monitored by Real-Time Emissive Color Switching

“…Undoubtedly, molecular motions, especially in the solid state, are responsible for macroscopic mechanical movements. 31,32 The photophysical properties of organic materials essentially depend on the molecular motions at the molecular levels. The emission color switching favors visual optical readouts and is readily monitored spectrophotometrically.…”