Construction of Multi‐Stimuli Responsive Highly Porous Switchable Frameworks by In Situ Solid‐State Generation of Spiropyran Switches

Abstract

Stimuli‐responsive molecular systems supported within permanently porous materials offer the opportunity to host dynamic functions operating multifunctional smart materials. However, the construction of highly porous frameworks featuring external‐stimuli responsiveness, for example by light excitation, is still in its infancy. Here we present a general strategy to construct spiropyran‐functionalized highly porous switchable aromatic frameworks (PSFs) by modular and high‐precision anchoring of molecular hooks and an innovative in‐situ solid‐state grafting approach. Three spiropyran‐grafted frameworks bearing distinct functional groups exhibiting various stimuli‐responsiveness were generated by two‐step post‐solid‐state synthesis of a parent indole‐based material. The quantitative transformation and preservation of high porosity were demonstrated by spectroscopic and gas adsorption techniques. For the first time, we provide a highly efficient strategy to construct multi‐stimuli‐responsive, yet structurally robust, spiropyran materials with high pore capacity which was proved essential for the reversible and quantitative isomerization in the bulk as demonstrated by solid‐state NMR spectroscopy. The overall strategy allowed to construct dynamic materials which undergo reversible transformation of spiropyran to zwitterionic merocyanine, by chemical and physical stimulation, showing potential for pH active control, responsive gas uptake and release, contaminant removal, and water harvesting.This article is protected by copyright. All rights reserved

Fluorescent Materials Based on Spiropyran for Advanced Anti-Counterfeiting and Information Encryption

“…Ongoing research efforts continue to explore novel synthetic strategies and to optimize their properties further, aimed at unlocking even more exciting applications in areas such as smart materials or advanced photonics technologies. There are a number of studies reporting on the synthesis of spiropyran compounds [ 25 , 26 , 27 , 28 , 29 ], and applications of spiropyran-based materials in fluorescent probes [ 30 , 31 , 32 , 33 , 34 , 35 ], advanced photoswitchable materials [ 36 , 37 , 38 , 39 , 40 ], and bioimaging [ 41 , 42 , 43 , 44 , 45 , 46 ]. However, we found no review on the design of fluorescent materials based on spiropyran for anti-counterfeiting.…”

Fabrication of efficient and red-emissive salicylaldehyde Schiff base isomers for multi-scenario information decryption

“…8–10 Due to their vast potential applications in anti-counterfeiting, 11,12 information encryption–decryption, 13,14 biochemical sensors, 15–18 and optoelectronic devices, 19,20 the development of SRFMs has gained significant attention in recent years. 21 Hence, many conventional stimuli-responsive molecular scaffolds, such as spiropyran, 22,23 azobenzenes, 24,25 dihydroazulenes, 26,27 diarylethenes, 28,29 and Schiff bases, 30,31 have been developed with dynamic covalent bonds for advanced applications. For example, the stimuli-responsive properties of Schiff bases are derived from the isomerization of the central CN double bonds and protonation processes of the nitrogen atom.…”

Orthogonal Photoswitching in a Porous Organic Framework

“…[42][43][44][45] Therefore, these porous structures constitute an ideal platform for the construction of light-responsive materials capable of harnessing limited changes in molecular geometry and transforming them into practical output. [36,46] Successful incorporation of single molecular photoswitches such as spiropyrans, [47][48][49][50][51][52][53] azobenzenes, [54][55][56][57] diarylethenes [58][59][60] and overcrowded alkenes [44,[61][62][63][64][65] into these structures generated a plethora of porous materials with switchable properties including electronic or ionic conductivity, gas uptake or ion capture. Despite these advances, all these materials operate by switching between only two states of the incorporated responsive molecules while, orthogonal photoswitching in solid state to alter multiple states of a single material remains rarely explored.…”