Visible responses under high pressure in crystals: phenolphthalein and its analogues with adjustable ring-opening threshold pressures

Deng, Xinyuan; Guo, Hongwei; Xiao, Meng; Wang, Kai; Zou, Bo; Ma, Yuguo

doi:10.1039/c9cc01145e

Cited by 14 publications

(4 citation statements)

References 49 publications

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“…Differing from the anisotropic force during uniaxial compression, DAC techniques can provide isotropic stress and offer in situ absorption and fluorescence spectra, as well as micrographs visualizing the pressure-dependent mechanochromic behavior. While the pressure-induced ring-opening isomerization has been achieved in spiropyran crystals, 53 phenolphthalein/polymer blends, 54 and rhodamine/cyclodextrin complex, 55 the pressureinduced bond scission of the DDM structure has never been reported. Notably, new bands at ∼650 nm appeared and the intensity grew significantly in the UV−vis spectra of TGDDM-EDR-Rh-0% during compression by DACs (Figures 7b and S22), which suggested that similar green chromophores could also generate under hydrostatic pressure.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores

Chen

Shao

et al. 2022

Macromolecules

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Mechanochromic polymers exhibit potential applications in damage reporting and stress sensing. Despite the rapid progress achieved in recent years, mechanochromic structural polymers, such as epoxy thermosets, remain difficult to develop, let alone structural materials that can distinguish different levels of stress by a visual color change. This work presents a new class of multicolor mechanochromic epoxy thermosets that can discriminate between low and high compressive stresses via the incorporation of two distinct mechanophores. Amino-functionalized rhodamine (Rh) moieties serve as efficient curing agents and ratiometric stress sensors for epoxy thermosets. The Rh mechanophore in the epoxy network can be activated either by scratch or uniaxial compression, showing a reversible color change and a red fluorescence turn-on response. A stress-dependent multicolor response under uniaxial compression and hydrostatic pressure is achieved by the combination of Rh mechanophores with a commercial epoxy resin containing a 4,4′-diaminodiphenylmethane (DDM) framework. The Rh zwitterion formed at a low compressive stress turns the sample red, while a high compressive stress turns the sample green via the formation of the quinoidal methine form of DDM. Differential activation under varying degrees of compressive stress is demonstrated by UV–vis spectroscopy. The facile preparation and ability to recognize stress intensity by the naked eye make this strategy suitable for practical applications.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores

Chen

Shao

et al. 2022

Macromolecules

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“…When the ground solid was fumed by THF, CH 2 Cl 2 , or chloroform, the fluorescence color recovered to green, and the fluorescence spectrum was also restored. Moreover, such color conversion could be repeated many times, suggesting a reversible process. − Interestingly, yellow HBC-1 solids were sheared; the color changed into orange red, and the sheared section emitted weak red fluorescence under 365 nm light. After shearing for 4 min, almost all the solids emitted an orange-red fluorescence (Figure , right).…”

Section: Resultsmentioning

confidence: 99%

π-Stacking Conversion and Enhanced Force-Stimuli Response of a Divinylanthracene Derivative in a Hydrogen-Bonded Framework

Han

Zhang

Qiao

et al. 2021

Crystal Growth & Design

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Hydrogen bond-induced π-stacking conversion was used to achieve an enhanced force-stimuli response of 9,10-bis(2-(pyridin-4-yl)vinyl)anthracene (BP4VA). In BP4VA crystals, the molecules adopted a J-aggregate pattern, and no overlap between the central anthracene planes was observed. Trimesic acid (TA) as a hydrogen bond donor could promote the transformation of the π-stacking type of BP4VA as a hydrogen bond acceptor. It was found that TA and BP4VA molecules formed two-dimensional lamellar hydrogen-bonded frameworks with large windows, which were filled by BP4VA molecules belonging to other layers. Within such three-dimensional packing, J-aggregate stacking type of BP4VA converted into a mixture of J-type and H-type dimers. Moreover, BP4VA adopted a highly twisted conformation, and π–π interaction between them was very weak. So, the hydrogen-bonded complex emitted a short wavelength fluorescence. More importantly, the yellow hydrogen-bonded complex turned into red solids under force stimuli, and its fluorescence had a fairly large shift of more than 110 nm. This is in contrast with a spectral shift of 43 nm from the sheared neat BP4VA crystals. Quantum chemical calculation and spectral observations implied that the planarization, shortened π-distance, and large overlap between anthracence units should be responsible for the large spectral shift. The results imply that the appropriate acid as a hydrogen bond donor might help distyrylanthracene derivatives possess outstanding functions.

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“…1,25–27 Under elevated pressures a decrease in the emissive response has traditionally been observed and attributed to an increase in π–π stacking interactions that leads to nonradiative decay. 27–33 Whereas an increase in the emissive response has been attributed to mechanisms such as RIR, RIM, the formation of exciton traps and an increase in radiative emission probabilities. 34–39 The emission spectrum is also affected under the application of pressure.…”

Section: Introductionmentioning

confidence: 99%

Understanding the solid state luminescence and piezochromic properties in polymorphs of an anthracene derivative

Aziz

Sidat

Talati

et al. 2022

Phys. Chem. Chem. Phys.

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Visible responses under high pressure in crystals: phenolphthalein and its analogues with adjustable ring-opening threshold pressures

Abstract: Visible mechanochromism was triggered via the ring-opening reaction of phenolphthalein under high pressure. Different ring-opening threshold pressures and responsive colors were achieved by changing the substituent groups with different electronic effects.

Cited by 14 publications

References 49 publications

Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores

Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores

π-Stacking Conversion and Enhanced Force-Stimuli Response of a Divinylanthracene Derivative in a Hydrogen-Bonded Framework

Understanding the solid state luminescence and piezochromic properties in polymorphs of an anthracene derivative

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