Polydiacetylene‐Tb³⁺ Nanosheets of Which Both the Color and the Fluorescence Can Be Reversibly Switched between Two Colors

Abstract

Polydiacetylenes (PDAs), an organic layered compound, show a series of intriguing properties, such as thermochromism and fluorescence emission in the red‐phase. However, their irreversible color change, and weak and single‐color fluorescence emitted only from the red‐phase PDAs, have limited their applications. Herein, we report double‐reversible PDA‐Tb3+ nanosheets of which both the color and the fluorescence can be reversibly switched between two colors. PDA‐Tb3+ nanosheets have the nearly defect‐free intercalated structure in which a layer of Tb3+ ions was intercalated in between each two PDA bilayers to tether almost all of the carboxyl groups at the end of the side chains of the PDA. When the PDA is in the blue phase, the PDA‐Tb3+ nanosheets emit the green fluorescence of Tb3+ ions. When the PDA is in the red phase, the Tb3+ fluorescence disappears while the intrinsic red fluorescence of PDA is effectively enhanced through the fluorescence resonance energy transfer (FRET) process; the PDA‐Tb3+ nanosheets emit stronger red fluorescence compared with the PDA in red phase. Moreover, the tethering of almost all of the carboxyl groups at the end of the side chains of the PDA endows the nanosheets with the double reversibility in both the color and fluorescence transitions.

Recent Developments in Polydiacetylene-Based Sensors

“…This remarkable thermochromism was attributed to the hierarchically assembled structure promoted by the multiple hydrogen bonds among the peptide segments. As alternatives for obtaining reversible thermochromism from a molecular level, intercalation with polymers, − organic amines, , layered double hydroxide nanosheets, and metal ions − to form layered nanocomposites or co-assembly with small molecule melamine was successfully employed.…”

A Photochromic Zinc–Viologen Framework with a High-Contrast Nonlinear Optical Switchable Behavior

“…According to previously reported chromic complexes, − a fluorescence switching process can occur during the photochromic process; thus, the switchable photoluminescence property of 1 was investigated. The emission peak appears at 539 nm upon excitation at 480 nm at room temperature before coloration (Figure S10).…”

Properties and Applications of Stimuli-Responsive Diacetylenes

“…Materials containing PCDA and PCDA derivatives have been successful in the detection of different metal ions, including alkali metals (lithium, sodium, , and cesium , ), transition metals (chromium­(III), manganese­(II), nickel­(II), copper­(II), zinc­(II), − silver­(I), , cadmium­(II), ,, iridium­(III), gold­(III), and mercury­(II), ,, ), post-transition metals and metalloids (aluminum­(III), arsenic­(III), , tin­(IV), and lead­(II) ,,− ), and the lanthanide element terbium­(III). , Many PCDA systems incorporating metal ions exhibit reversible thermochromism due to the enhanced electrostatic interactions between the cations and the carboxylate headgroup of PCDA, allowing the structural recovery of the conjugated backbone after the heat stimulus is removed . Nanocomposites comprising the intercalation of zinc oxide nanoparticles into PCDA assemblies have been studied by powder X-ray diffraction to investigate the effect of metal ions on the interlamellar d spacing of PCDA .…”

“…The color transition of the vesicles when they are in contact with lanthanide ions is due to the distortion of the calixarene cavity, which ultimately disturbs the polydiacetylene backbone, alongside metal-induced aggregation and sedimentation of the vesicles . An additional lanthanide ion that has been used in combination with PCDA is terbium­(III), with bilayers of PCDA being intercalated with terbium­(III) ions positioned at the carboxyl headgroup of PCDA . The nanosheets of PCDA-Tb­(III) exhibited reversible thermochromism and reversible fluorescence up to temperatures of 90 °C …”

“…146 The nanosheets of PCDA-Tb(III) exhibited reversible thermochromism and reversible fluorescence up to temperatures of 90 °C. 146 Effect of Mechanical Stress on PCDA Polymer Properties. The first observation of mechanochromism in PCDA films on the nanometer scale was reported by Carpick and co-workers by atomic force microscopy (AFM) and near-field scanning optical microscopy (NSOM) accompanied by interfacial force microscopy.…”