Acid-, mechano- and photochromic molecular switches based on a spiropyran derivative for rewritable papers

Abstract

In this work, we report a novel acid-, photo- and mechanochromic material based on a spiropyran (SP) derivative.

Dual-stimuli response of spiropyran derivative modified by long-chains: high-contrast photochromism and mechanochromism

“…S6 (ESI†), the decomposition temperature ( T d , the temperature of 5% weight loss) of this molecule was 280 °C. Compared with other similar stimuli-responsive molecules reported before, 19,44,50 the thermal stability of TDBA-SP was quite excellent, which can meet the needs of practical application. Meanwhile, the lower melting point (about 58 °C) made it is easier to process (Fig.…”

“…In particular, the mechanochromism can provide abundant anti-counterfeiting means, such as personal handwriting and individualized marking, providing a better encryption guarantee. Unlike our previous research on increasing the free volume of spiropyran only by adding rigid groups, 20,35,43,44 the use of 3,4,5-tri-dodecyloxybenzoic acid introduces a rigid benzene ring and flexible long chains to spiropyran, which gives the color-changing molecule additional advantages. Firstly, most of the previously reported dual-stimuli responsive materials were modified by introducing rigid groups into spiropyran, such as naphthalimide or a silane group.…”

Application of Super Photoacids in Controlling Dynamic Processes: Light-Triggering the Self-Propulsion of Oil Droplets

“…This is the governing mechanism behind the self-propulsion of the droplet, i.e., that the protonation of the acceptor situated on the surface of the droplet changes the surface tension and induces self-propulsion. It is worth mentioning that another class of molecules is also being referred to as photoacids, which are based on the photochromic structural change of the molecule, whereas the most known representative of this class is the spiropyran–merocyanine system. − During the photochromic structural change of such molecules, a proton is being released, and hence it is also referred to as a photoacid. However, since the reversible photochromism mechanism is orders of magnitude slower compared to the ESPT process and proton recombination of Brønsted photoacids, the working mechanism of using photochromic photoacids is via the transient acidification of the solution (i.e., a pH change) and not a direct proton transfer between the donor and the acceptor.…”

A simple fluorescent switch with four states based on benzothiazole-spiropyran for reversible multicolor displays and anti-counterfeiting

“…15,16 and fluorophores into one molecule, a series of FMSs have been achieved, [17][18][19][20] which not only expands the stimuli species, but also enriches the output signals. FMSs have been widely researched for versatile applications, such as smart materials, 21 chemical sensors, 22,23 displays 24 and bioimaging 25 owing to their excellent response to diverse external stimuli. In general, most of the FMSs were achieved by linking individual switches to other fluorophores with covalent or non-covalent bonds (Scheme 1a), which led to the remarkable development of many luminescence switches showing distinctive emission characteristics.…”

“…In general, most of the FMSs were achieved by linking individual switches to other fluorophores with covalent or non-covalent bonds (Scheme 1a), which led to the remarkable development of many luminescence switches showing distinctive emission characteristics. [24][25][26][27][28][29] However, switching motifs with fewer and simpler units are more beneficial and plausible from the point of view of atomic efficiency. [30][31][32] Therefore, FMSs by fusing a single switch to a fluorophore through a shared central unit were designed, which was an effective and efficient method to construct FMSs with both emission color change and on/off switching (Scheme 1b).…”