Mechanochromism induced through the interplay between excimer reaction and excited state intramolecular proton transfer

Wei, Yu‐Chen; Zhang, Zhiyun; Chen, Yi‐An; Wu, Cheng‐Ham; Liu, Zong‐Ying; Ho, Ssu-Yu; Liu, Jiun-Chi; Lin, Jia‐An; Chou, Pi‐Tai

doi:10.1038/s42004-019-0113-8

Cited by 29 publications

(13 citation statements)

References 48 publications

(54 reference statements)

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“…Among a variety of H-bond associated research directions, one field should be credited to the proton transfer reaction in the electronically excited state. − Upon photoexcitation, driven by the changes of the acidity and basicity in the excited state, the transfer of a proton from the OH or NH proton-donating site to the O or N proton-accepting site becomes feasible. When it takes place within the molecular unit, the process is dubbed as the excited-state intramolecular proton transfer (ESIPT), which has been receiving considerable attention in both fundamental − and applied researches. − On the one hand, the result of ESIPT forms a proton-transfer isomer, namely, the tautomer, in the excited state, which does not exist in the ground state thermally and accordingly gives rise to an anomalously large Stokes shift emission (cf. the non-proton transfer, normal emission).…”

Section: Introductionmentioning

confidence: 99%

Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution

et al. 2021

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We report here, for the first time, the experimental observation on the excited-state intramolecular proton transfer (ESIPT) reaction of the thiol proton in room-temperature solution. This phenomenon is demonstrated by a derivative of 3-thiolflavone (3TF), namely, 2-(4-(diethylamino)phenyl)-3mercapto-4H-chromen-4-one (3NTF), which possesses an SH•••O intramolecular H-bond (denoted by the dashed line) and has an S 1 absorption at 383 nm. Upon photoexcitation, 3NTF exhibits a distinctly red emission maximized at 710 nm in cyclohexane with an anomalously large Stokes shift of 12 230 cm −1 . Upon methylation on the thiol group, 3MeNTF, lacking the thiol proton, exhibits a normal Stokes-shifted emission at 472 nm. These, in combination with the computational approaches, lead to the conclusion of thiol-type ESIPT unambiguously. Further time-resolved study renders an unresolvable (<180 fs) ESIPT rate for 3NTF, followed by a tautomer emission lifetime of 120 ps. In sharp contrast to 3NTF, both 3TF and 3-mercapto-2-(4-(trifluoromethyl)phenyl)-4Hchromen-4-one (3FTF) are non-emissive. Detailed computational approaches indicate that all studied thiols undergo thermally favorable ESIPT. However, once forming the proton-transferred tautomer, the lone-pair electrons on the sulfur atom brings nonnegligible nπ* contribution to the S 1 ′ state (prime indicates the proton-transferred tautomer), for which the relaxation is dominated by the non-radiative deactivation. For 3NTF, the extension of π-electron delocalization by the diethylamino electron-donating group endows the S 1 ′ state primarily in the ππ* configuration, exhibiting the prominent tautomer emission. The results open a new chapter in the field of ESIPT, covering the non-canonical sulfur intramolecular H-bond and its associated ESIPT at ambient temperature.

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Section: Introductionmentioning

confidence: 99%

Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution

et al. 2021

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“…Chou and co‐workers developed an interesting strategy that combined the ESIPT and excimer emission for the generation of solid‐state white light . The solid powder of 2,2′‐(thiazolo[5,4‐ d ]thiazole‐2,5‐diyl)bis(4‐(trifluoromethyl)phenol (CF 3 ‐HTTH) exhibited multiple emission bands located at around 460 nm (N*: normal enol emission), 520 nm (T*: tautomer emission), and 600 nm (E*: excimer emission).…”

Section: White Light Emission Through a Combination Of Multiple Appromentioning

confidence: 99%

“…The layer‐by‐layer structure of CF 3 ‐HTTH induced by the ‐CF 3 groups further facilitates the excimer formation. In addition, the hydrogen‐bonding interactions of C−F⋅⋅⋅H−C between two adjacent CF 3 ‐HTTH molecules favor the excimer formation …”

Section: White Light Emission Through a Combination Of Multiple Appromentioning

confidence: 99%

“…The forward, backward proton transfer rate constants and the rate constant for excimer formation are denoted by k pt , k −pt , and k exm , respectively. Figure adapted from reference under the Creative Commons Attribution 4.0 International License, which permits the unrestricted use, distribution, modification, and reproduction of the contents from this article.…”

Section: White Light Emission Through a Combination Of Multiple Appromentioning

confidence: 99%

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Molecular Engineering Approaches Towards All‐Organic White Light Emitting Materials

Kundu

Pallavi

et al. 2020

Chemistry A European J

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White light emitting (WLE) materials are of increasing interesto wing to their promising applicationsi na rtificial lighting, display devices, molecular sensors, and switches.I n this context,o rganic WLE materials cater to the interesto f the scientific community owing to their promising features like color purity,l ong-term stability,s olutionp rocessability, cost-effectiveness,a nd low toxicity.T he typical methodf or the generation of white light is to combine three primary (red, green, and blue) or the two complementary (e.g., yellow and blue or red and cyan) emissive units covering the whole visible spectralw indow (400-800 nm). The judicious choice of molecular buildingb locks and connecting them through either strong covalentb onds or assembling through weakn oncovalent interactions are the key to achieve enhanced emissions panning the entire visible region.In the present review article, moleculare ngineering approaches for the development of all-organic WLE materials are analyzed in view of different photophysical processes like fluorescencer esonance energy transfer (FRET), excitedstate intramolecular protont ransfer (ESIPT), charget ransfer (CT), monomer-excimer emission, triplet-state harvesting, etc. The key aspect of tuning the molecular fluorescence under the influence of pH, heat, and host-guest interactions is also discussed. The white light emission obtained from small organic molecules to supramolecular assemblies is presented,i ncluding polymers, micelles,a nd also employing covalent organic frameworks. The state-of-the-art knowledge in the field of organic WLE materials, challenges, and future scope are delineated.

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“…When excited by a photosource, the electronic charge can be redistributed. As a result, the acidity of the proton donor and the basicity of the proton acceptor are increased, leading to an extremely fast ( k ept > 10 12 s –1 ) proton transfer from the proton donor to the proton acceptor via the intramolecular hydrogen bond. − Meanwhile, the excited E* form is transformed into the excited keto (K*) form (Scheme ). The K* form can decay to its ground state by fluorescent emission, and then the unstable ground K form can easily convert into the original E form via a reverse proton transfer (RPT).…”

Section: Fundamentals Of Esipt Processmentioning

confidence: 99%

Organic Lasers Harnessing Excited State Intramolecular Proton Transfer Process

2020

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Excited state intramolecular proton transfer (ESIPT) molecules are considered to be natural born laser materials because of their intrinsic four-level system. Organic lasers based on ESIPT materials, especially recently developed micro/nanolasers, have been drawing great attention in the past few decades due to their unique photophysical properties, such as ultralow threshold and high-quality value, as well as near-infrared (NIR) and wavelength tunable emission. These photophysical properties facilitate their widespread applications in lasing communication, ultrasensitive sensing, biological imaging, data storage and on-chip optical circuits. In this Review, first, the ESIPT process is introduced concisely. Second, recent advances of ESIPT-based organic lasers in solution, film and crystal states are reviewed. Finally, the current challenges and future development of ESIPT-based organic lasers are presented.

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Mechanochromism induced through the interplay between excimer reaction and excited state intramolecular proton transfer

Cited by 29 publications

References 48 publications

Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution

Chapter Open for the Excited-State Intramolecular Thiol Proton Transfer in the Room-Temperature Solution

Molecular Engineering Approaches Towards All‐Organic White Light Emitting Materials

Organic Lasers Harnessing Excited State Intramolecular Proton Transfer Process

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