Tunable mechanochromic luminescence <i>via</i> surface protonation of pyridyl-substituted imidazole crystals

Kubota, Rikuto; Yuan, Yanqiu; Yoshida, Ryohei; Tachikawa, Takashi; Ito, Suguru

doi:10.1039/d2ma00256f

Cited by 7 publications

(1 citation statement)

References 65 publications

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“…The emission efficiency and emission color of AIEgens were tuned by tailoring the molecular structure and intermolecular interactions . The intermolecular interactions rigidify the molecule in the solid state and restrict the intramolecular rotation that facilitates enhanced radiative transition. , The twisted molecular conformation and subtlety of intermolecular interactions of AIEgens were further used for developing smart fluorescence materials that exhibit sensitive response to the external stimuli. − Moreover, developing dual-state emitting fluorophores is comparatively interesting since they can be utilized both at molecular as well as aggregated states . For example, integrating functional group such coordinating and acid-responsive functionality allowed us to fabricate chemical/pH sensors and acid/base-dependent fluorescence switches, which can be employed to fabricate rewritable/self-erasable fluorescence platforms by integrating into the polymer matrix. ,, However, dual-state emitting stimuli-responsive fluorophores are relatively less reported compared to AIEgens and require special structural features.…”

Section: Introductionmentioning

confidence: 99%

Multistimuli Fluorescence-Responsive TPA/TPE-Imidazo[1,2-a]pyridine π-Conjugated Donor–Acceptor Derivatives and Effect of Donor Structures

Issac,

Ravi,

Chidambaranathan

et al. 2024

Crystal Growth & Design

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Triphenylamine (TPA) and tetraphenylethylene (TPE) πconjugated imidazo[1,2-a]pyridine (IP) donor−acceptor compounds, TPA-IP and TPE-IP, were synthesized, and the TPA/TPE-dependent stimuliresponsive fluorescence switching in the solid and solution state was investigated. TPA-IP and TPE-IP revealed a twisted molecular conformation and adopted opposite molecular dipole arrangement in the solid state. TPA-IP exhibited dual-state fluorescence [λ max = 441 nm (solid) and 387 nm (hexane), quantum yield (Φ f ) = 1.86% (solid) and 0.089 (compared to quinine sulfate)], whereas TPE-IP showed typical aggregation-induced emission in the solid state (λ max = 445, Φ f = 6.21%). Mechanoresponsive studies of TPE-IP showed self-reversible fluorescence switching upon mechanical grinding and acid exposure. In contrast, TPA-IP exhibited reversible fluorescence switching upon mechanical grinding/heating and acid/base exposure. In solution, TPA-IP exhibited pH-dependent tuneable fluorescence from blue to yellow due to protonation of imidazo-pyridine nitrogen including white light emission at optimized acid concentrations. Computational studies of TPA-IP indicated clear charge transfer from TPA donor to IP acceptor, whereas electron density mostly occupied in the IP in highest occupied molecular orbital and lowest unoccupied molecular orbital of TPE-IP, indicating locally excited state emission. This was further supported by electrochemical cyclic voltammetry that showed a relatively low band gap for TPA-IP compared to TPE-IP. Thus, integrating twisted donor (TPA/ TPE) with the imidazo-pyridine acceptor produced fluorophores with donor-dependent tuneable fluorescence and multistimuliresponsive fluorescence switching.

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Section: Introductionmentioning

confidence: 99%

Multistimuli Fluorescence-Responsive TPA/TPE-Imidazo[1,2-a]pyridine π-Conjugated Donor–Acceptor Derivatives and Effect of Donor Structures

Issac,

Ravi,

Chidambaranathan

et al. 2024

Crystal Growth & Design

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Mechanoresponsive Fluorescence On‐off Switching of Two‐component Emitters Composed of Mechanochromically Luminescent Dyes and Non‐emissive Pigments

Kubota

Takahashi

Nagai

et al. 2023

Chemistry An Asian Journal

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Organic emitters capable of changing their luminescence properties in response to mechanical stimuli have recently attracted considerable attention. While mechanoresponsive switching of luminescence color has been widely investigated, there are only a limited examples regarding the on-off luminescence intensity switching by mechanical stimulation. Consequently, rational design guidelines for mechanoresponsive switching of luminescence intensity have not been established. Herein, on-off luminescence switching has been achieved by two-component organic emitters composed of phenanthroimidazolylbenzothiadiazoles, which ex-hibit mechanochromic luminescence (MCL), and non-emissive pigments. In these two-component emitters, the emission color can be tuned by changing the MCL dye, and the apparent color under room light can be modulated by changing the non-emissive pigment. Moreover, we have demonstrated the encryption and decryption of luminescent displays by using the two-component emitter. The present two-component strategy is expected to serve as a useful method for developing advanced mechanoresponsive luminescent materials.

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Dual‐Stimuli‐Responsive Turn‐On Luminescence of Chiral Bisimidazolyl BINOL Dimethyl Ether Crystals

Murata,

Suzuki,

Terakubo

et al. 2024

Chemistry An Asian Journal

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Stimuli‐responsive organic luminescent crystals have attracted significant attention in recent years for their potential in sensor and memory applications. While turn‐on luminescence is superior in detection sensitivity compared with turn‐off luminescence, the development of organic crystals that exhibit turn‐on luminescence in response to multiple stimuli remains a significant challenge. Herein, the crystals of chiral bisimidazolyl 1,1′‐bi‐2‐naphthol (BINOL) dimethyl ether have exhibited a dual‐stimuli‐responsive turn‐on luminescence based on two distinct mechanisms. In the crystalline state, luminescence was substantially quenched by the intermolecular hydrogen bonds between the imidazole rings. Mechanical stimulation induced a transition to a blue‐violet‐emissive amorphous state. In contrast, thermal stimulation produced an orange luminescence, attributed to excited‐state intramolecular proton transfer (ESIPT) luminescence from thermally demethylated products. Furthermore, the thermally induced state exhibited circularly polarized luminescence (CPL), marking a rare instance of stimuli‐responsive turn‐on CPL in a solid‐state system. This study provides new insights into environmental and structural factors for solid‐state luminescent properties and advances the design guidelines for multifunctional luminescent sensors.

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Tunable mechanochromic luminescence via surface protonation of pyridyl-substituted imidazole crystals

Abstract: Over the past decade, a growing number of luminescent organic materials exhibiting mechanochromic luminescence (MCL) have been developed, but controlling the magnitude of the mechanically induced shift in emission wavelength...

Cited by 7 publications

References 65 publications

Multistimuli Fluorescence-Responsive TPA/TPE-Imidazo[1,2-a]pyridine π-Conjugated Donor–Acceptor Derivatives and Effect of Donor Structures

Multistimuli Fluorescence-Responsive TPA/TPE-Imidazo[1,2-a]pyridine π-Conjugated Donor–Acceptor Derivatives and Effect of Donor Structures

Mechanoresponsive Fluorescence On‐off Switching of Two‐component Emitters Composed of Mechanochromically Luminescent Dyes and Non‐emissive Pigments

Dual‐Stimuli‐Responsive Turn‐On Luminescence of Chiral Bisimidazolyl BINOL Dimethyl Ether Crystals

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