- 标题
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Versatile and Switchable Responsive Properties of a Lanthanide-Viologen Metal-Organic Framework
摘要： Metal–organic frameworks (MOFs) provide intriguing platforms for the design of responsive materials. It is challenging to mobilize as many components as possible of a MOF to collaboratively accomplish multiple responsive properties. Here, reversible photochromism, piezochromism, hydrochromism, ionochromism, and luminescence modulation of an ionic Eu(III) MOF is reported furnished by cationic electron-deficient viologen units and exchangeable guest anions. Mechanistically, the extraordinarily versatile responsive properties are owed to electron transfer (ET), charge transfer (CT), and energy transfer, involving viologen as electron acceptor, anion as electron donor, luminescing Eu(III) as energy donor, and anion-viologen CT complex or ET-generated radical as energy acceptor (luminescence quencher). Moreover, guest anions and waters provide flexible handles to control the ET-based responsive properties. Water release/reuptake or exchange with organic solvents can switch on/off the response to light, while reversible anion exchange can disenable or awaken the responses to pressure, light, and water release/reuptake. The impacts of water and anions on ET are justified by the high polarity and hydrogen-bonding capability of water, the different electron donor strength of anions, and the strong I?-viologen CT interactions. The rich responsive behaviors have great implications for applications such as pressure sensors, iodide detection, and chemical logic gates.
关键词： metal–organic frameworks,electron transfer,charge transfer,luminescence switches,piezochromism
更新于2025-09-23 15:23:52
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Remarkable responsive behaviors of iso-aminobenzopyranoxanthenes: protonation effect, photochromism and piezochromism
摘要： The iso-cis/trans-aminobenzopyranoxanthenes (iso-cis/trans-ABPXs), as one of popular leuco dyes, were investigated in solution or crystal phase. The introduction of benzo-pentacyclic-ester group in iso-cis/trans-ABPXs leads to remarkable multi-stimuli responsive behaviors, including protonation effect, photochromism and piezochromism with notable color changes. The iso-cis/trans-ABPXs show different in the responsive sensitivity and the iso-cis-ABPX is highly sensitive to environmental stimuli relative to the trans-form, which can be explained by their different C-H?O interaction and/or C-O bond length. Interestingly, as the ultraviolet light irradiation time increasing, the iso-cis/trans-ABPXs solution gradually becomes transparent and orange precipitates are achieved, which is identified as iso-ABPXs ±. Multi-stimuli responsive behaviors on the iso-cis/trans-ABPXs provide a comprehensive insight into the chromogenic mechanisms of this type of materials, suggesting that they may be potential candidate materials for sensors and indicators.
关键词： Protonation effect,Piezochromism,Photochromism,Spirolactone ring,Tautomerizm
更新于2025-09-10 09:29:36