The Cyclic Hydrogen‐Bonded 6‐Azaindole Trimer and its Prominent Excited‐State Triple‐Proton‐Transfer Reaction

Tu, Ting-Hsun; Chen, Yi-Ting; Chen, Yi‐An; Wei, Yu‐Chen; Chen, Youhua; Chen, Chi‐Lin; Shen, Jau-Ji; Chen, Yihan; Ho, Ssu-Yu; Cheng, Kum‐Yi; Lee, Shern‐Long; Chou, Pi‐Tai

doi:10.1002/anie.201800944

Cited by 11 publications

(12 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Eventually, we anticipate that further studies on the ESPT mechanism should make progress on the following aspects: (1) developing and searching new functionals that can provide more accurate PES for ESPT reactions; (2) extending the studies to systems involving multiple protons transfer; 66 (3) constructing the PES by optimization of the TS and performing IRC calculations; (4) accounting for the solvent effects by QM/MM; (5) performing AIMD calculations and then comparing with ultrafast time-resolved spectra. These strategies will provide deeper insights into the ESPT mechanism.…”

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

2018

View full text Add to dashboard Cite

As one of the most fundamental processes, excited-state proton transfer (ESPT) plays a major role in both chemical and biological systems. In the past several decades, experimental and theoretical studies on ESPT systems have attracted considerable attention because of their tremendous potential in fluorescent probes, biological imaging, white-light-emitting materials, and organic optoelectronic materials. ESPT is related to fluorescence properties and usually occurs on an ultrafast time scale at or below 100 fs. Consequently, steady-state and femtosecond time-resolved absorption, fluorescence, and vibrational spectra have been used to explore the mechanism of ESPT. However, based on previous experimental studies, direct information, such as transition state geometries, energy barrier, and potential energy surface (PES) of the ESPT reaction, is difficult to obtain. These data are important for unravelling the detailed mechanism of ESPT reaction and can be obtained from state-of-the-art ab initio excited-state calculations. In recent years, an increasing number of experimental and theoretical studies on the detailed mechanism of ESPT systems have led to tremendous progress. This Account presents the recent advances in theoretical studies, mainly those from our group. We focus on the cases where the theoretical studies are of great importance and indispensable, such as resolving the debate on the stepwise and concerted mechanism of excited-state double proton transfer (ESDPT), revealing the sensing mechanism of ESPT chemosensors, illustrating the effect of intermolecular hydrogen bonding on the excited-state intramolecular proton transfer (ESIPT) reaction, investigating the fluorescence quenching mechanism of ESPT systems by twisting process, and determining the size of the solute·(solvent) n cluster for the solvent-assisted ESPT reaction. Through calculation of vertical excitation energies, optimization of excited-state geometries, and construction of PES of the ESPT reactions, we provide modifications to experimentally proposed mechanisms or completely new mechanism. Our proposed new and inspirational mechanisms based on theoretical studies can successfully explain the previous experimental results; some of the mechanisms have been further confirmed by experimental studies and provided guidance for researchers to design new ESPT chemosensors. Determination of the energy barrier from an accurate PES is the key to explore the ESPT mechanism with theoretical methods. This approach becomes complicated when the charge transfer state is involved for time-dependent density functional theory (TDDFT) method and optimally tuned range-separated TDDFT provides an alternative way. To unveil the driving force of ESPT reaction, the excited-state molecular dynamics combined with the intrinsic reaction coordinate calculations can be employed. These advanced approaches should be used for further studies on ESPT systems.

show abstract

Section: Accounts Of Chemical Researchmentioning

confidence: 99%

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

2018

View full text Add to dashboard Cite

show abstract

“…Recently, excited-state intramolecular proton transfer (ESIPT) molecules are of great interest for the design of new Al 3+ probes , because of their ultrafast reaction rate and huge fluorescence Stokes shifts. In general, the ESIPT process requires adjacent proton donor (−OH or −NH 2 ) and proton acceptor (−CO or −N) groups to generate the intramolecular hydrogen bond. − The enol isomer in lower energy in the electronic ground state will undergo a proton transfer reaction upon excitation to the excited state. − Upon irradiation, these molecules produce the keto forms as ESIPT tautomers, which show stronger fluorescence at longer wavelength compared with the phenol forms. For example, 2-(2-hydroxyphenyl)benzothiazole, 2-(2′-hydroxyphenyl)benzoxazole, and 2-hydroxybenzcarbaldehyde-(2-methylquinoline-4-formyl)hydrazone have been reported as fluorescent sensors for Al 3+ .…”

Section: Introductionmentioning

confidence: 99%

Highly Selective and Sensitive Turn-Off–On Fluorescent Probes for Sensing Al³⁺ Ions Designed by Regulating the Excited-State Intramolecular Proton Transfer Process in Metal–Organic Frameworks

Li¹,

Zhu²,

Li³

et al. 2019

ACS Appl. Mater. Interfaces

174

125

View full text Add to dashboard Cite

The concept of high-performance excited-state intramolecular proton transfer (ESIPT)-based fluorescent metal− organic framework (MOF) probes for Al 3+ is proposed in this work. By regulating the hydroxyl groups on the organic linker step by step, new fluorescent magnesium−organic framework (Mg−MOF) probes for Al 3+ ions were established based on the ESIPT fluorescence mechanism. It is observed for the first time that the number of intramolecular hydrogen bonds between adjacent hydroxyl and carboxyl groups can effectively adjust the ESIPT process and lead to tunable fluorescence sensing performance. Together with the well-designed porous and anionic framework, the Mg−TPP−DHBDC probe decorating with a pair of intramolecular hydrogen bonds exhibits extra-high quantitative fluorescence response to Al 3+ through an unusual turn-off (0−1.2 μM) and turn-on (4.2−15 μM) luminescence sensing mechanism. Notably, the 28 nM limit of detection value represents the lowest record among all reported MOF-based Al 3+ fluorescent sensors up to now. Benefited from the unique turn−off−on ESIPT fluorescence detection process, the Mg−TPP−DHBDC MOF sensor exhibits single Al 3+ detection compared with other 16 common metal ions including Ga 3+ , In 3+ , Fe 3+ , Cr 3+ , Ca 2+ , and Mg 2+ . Impressively, such an Al 3+ selective sensing process can even be fulfilled by the reusable MOF test paper detected by naked eyes. Overall, the quantitative Al 3+ detection, together with the extraordinary sensitivity, selectivity, fast response, and good reusability, strongly supports our concept of ESIPT-based fluorescent MOF Al 3+ probes and makes Mg−TPP−DHBDC one of the most powerful Al 3+ fluorescent sensors.

show abstract

“…Currently, there have been few reports on ESTPT in organic molecules, which are limited to intermolecular processes. In 2018, Chou et al [17] reported the first ESTPT using a 6-AI trimer. Because of steric hindrance, intramolecular and intermolecular hydrogen bonds between the two 6-AI molecules cannot be formed.…”

Section: Excited-state Intermolecular Triple Proton Transfermentioning

confidence: 99%

“…In 2015, Chou et al [16] reported a typical cascaded ESIDPT. In 2018, the first excited-state triple proton transfer (ESTPT) was experimentally observed in the trimer of 6-azaindole (6-AI) by Chen et al [17].…”

Section: Introductionmentioning

confidence: 99%

Recent progress on the excited-state multiple proton transfer process in organic molecules

et al. 2022

View full text Add to dashboard Cite

In contrast to the widely reported excited-state single proton-transfer, excited-state multiple proton transfer (ESMPT) containing two or more intra-or inter-molecular proton transfers has greatly expanded the research scope of the excited-state proton transfers. In recent decades, ESMPT-active organic molecules have attracted much attention owing to their unique photophysical properties, such as large magnitude Stokes shifts and dual emission. These photophysical properties facilitate the application of the organic molecules in organic solid-state lasers, fluorescent probes and sensors, and molecular switches. Herein, we introduce the fundamentals of the ESMPT and review the recent advances in different types of ESMPTs in organic molecules. Finally, we present our conclusions and the future development prospects of the ESMPT in organic molecules. excited-state multiple proton transfer, hydrogen bond, photoisomerization, organic molecules, photophysical properties

show abstract

The Cyclic Hydrogen‐Bonded 6‐Azaindole Trimer and its Prominent Excited‐State Triple‐Proton‐Transfer Reaction

Cited by 11 publications

References 26 publications

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

Highly Selective and Sensitive Turn-Off–On Fluorescent Probes for Sensing Al³⁺ Ions Designed by Regulating the Excited-State Intramolecular Proton Transfer Process in Metal–Organic Frameworks

Recent progress on the excited-state multiple proton transfer process in organic molecules

Contact Info

Product

Resources

About

The Cyclic Hydrogen‐Bonded 6‐Azaindole Trimer and its Prominent Excited‐State Triple‐Proton‐Transfer Reaction

Cited by 11 publications

References 26 publications

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

Unraveling the Detailed Mechanism of Excited-State Proton Transfer

Highly Selective and Sensitive Turn-Off–On Fluorescent Probes for Sensing Al3+ Ions Designed by Regulating the Excited-State Intramolecular Proton Transfer Process in Metal–Organic Frameworks

Recent progress on the excited-state multiple proton transfer process in organic molecules

Contact Info

Product

Resources

About

Highly Selective and Sensitive Turn-Off–On Fluorescent Probes for Sensing Al³⁺ Ions Designed by Regulating the Excited-State Intramolecular Proton Transfer Process in Metal–Organic Frameworks