Turning ON/OFF the fluorescence of the ESIPT state by changing the hydrogen bond distance and orientation in quinoline–pyrazole derivatives

Li, Hui; Mu, Hongyan; Xin, Chao; Cai, Jixing; Yuan, Boshi; Jin, Guangyong

doi:10.1016/j.molstruc.2021.132146

Cited by 14 publications

(4 citation statements)

References 49 publications

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“…However, the quinoline moiety is only rarely involved in the design and theoretical studies of ESIPT-capable molecules. [139][140][141][142][143][144][145][146][147][148][149][150][151][152][153][154][155][156] What is important for coordination chemistry in the case of HL q is that this new ESIPT-system still features a metal binding site and can be used for the synthesis of ESIPT-capable metal complexes as its predecessor HL p is. Finally, since ESIPT-fluorophores tend to luminesce with low quantum yields resulting from significant structural reorganization accompanying the ESIPT process, a natural choice for improving their efficiency through chelation-enhanced fluorescence (CHEF) seems to be Zn 2+ ion.…”

Section: Introductionmentioning

confidence: 99%

Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(ii) complexes with 1-hydroxy-1H-imidazole-based ligands

et al. 2022

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Section: Introductionmentioning

confidence: 99%

Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(ii) complexes with 1-hydroxy-1H-imidazole-based ligands

et al. 2022

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“…The excited-state intramolecular proton-transfer (ESIPT) process was a photophysical process that induced the isomerization of intramolecular hydrogen bonds (IHBs) from enol to keto in organic molecules after photoexcitation. − The presence of ESIPT resulted in a reduction of the first singlet energy level − and a redshift of the emission wavelength; − thus, the ESIPT molecule usually had a large Stokes shift. − Molecules with ESIPT properties were considered to have potential applications in fluorescence probes, − organic luminescent materials, − and biomedicine. − In 1950, Weller first reported the ESIPT process in methyl salicylate . Subsequently, numerous scholars were committed to exploring the molecular mechanism of the ESIPT reaction and its application value both experimentally and theoretically …”

Section: Introductionmentioning

confidence: 99%

Photophysical Properties of (E)-1-(4-(Diethyla-mino)-2-hydroxybenzylidene)-4,4-dimethylthiosemicarbazide Compound and Its Triple Fluorescence Emission Mechanism: A Theoretical Perspective

Sun,

Mu,

Wang

et al. 2024

J. Phys. Chem. A

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In view of the application prospects in biomedicine of (E)-1-(4-(diethyla-mino)-2-hydroxybenzylidene)-4,4-dimethylthiosemicarbazide (DAHTS), the behavior of excited-state dynamics and photophysical properties were studied using the density functional theory/time-dependent density functional theory method. A series of studies indicated that the intramolecular hydrogen-bond (IHB) intensity of DAHTS was enhanced after photoexcitation. This was conducive to promoting the excited-state intramolecular proton-transfer (ESIPT) process. Combining the analysis of the IHB and hole–electron, it revealed that the molecule underwent both the ESIPT process and the twisted charge-transfer (TICT) process. Relying on exploration of the potential energy surface, it was proposed that the different competitive mechanisms between the ESIPT and TICT processes were regulated by solvent polarity. In acetonitrile (ACN) solvent, the ESIPT process occurred first, and the TICT process occurred later. In contrast, in the CYH solvent, the molecule first underwent the TICT process and then the ESIPT process. Furthermore, we raised the possibility that the TICT behavior was the cause of weak fluorescence emission for the DAHTS in CYH and ACN solvents. By the dimer correlation analysis, the corresponding components of triple fluorescence emission were clearly assigned, corresponding to the monomer, dimer, and ESIPT isomer in turn. Our work precisely elucidated the photophysical mechanism of DAHTS and the attribution of the triple fluorescence emission components, which provided valuable guidance for the development and regulation of bioactive fluorescence probes with multiband and multicolor emission characteristics.

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“…Hydrogen bonds (HBs) are chemical bonds formed by interactions between hydrogen atoms and atoms with higher electronegativity (such as nitrogen, oxygen or fluorine) and are among the most important weak interactions within and between molecules [1][2][3][4][5][6]. Owing to their specific saturation and directivity [7][8][9][10], HBs play an extremely vital role in the fields of chemistry, physics and biology [11][12][13][14][15][16]. Excited-state intramolecular proton transfer (ESIPT) is a photophysical process that promotes the interconversion isomerisation between enol and keto in molecules under photoexcitation [17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Modulating the ESIPT Mechanism and Luminescence Characteristics of Two Reversible Fluorescent Probes by Solvent Polarity: A Novel Perspective

Wang,

Mu,

Sun

et al. 2024

Molecules

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As reversible fluorescent probes, HTP-1 and HTP-2 have favourable applications for the detection of Zn2+ and H2S. Herein, the impact of solvent on the excited-state intramolecular proton transfer (ESIPT) of HTP-1 and HTP-2 was comprehensively investigated. The obtained geometric parameters and infrared (IR) vibrational analysis associated with the intramolecular hydrogen bond (IHB) indicated that the strength of IHB for HTP-1 was weakened in the excited state. Moreover, structural torsion and almost no ICT behaviour indicated that the ESIPT process did not occur in HTP-1. Nevertheless, when the 7-nitro-1,2,3-benzoxadiazole (NBD) group replaced the H atom, the IHB strength of HTP-2 was enhanced after photoexcitation, which inhibited the twisting of tetraphenylethylene, thereby opening the ESIPT channel. Notably, hole-electron analysis and frontier molecular orbitals revealed that the charge decoupling effect was the reason for the fluorescence quenching of HTP-2. Furthermore, the potential energy curves (PECs) revealed that HTP-2 was more inclined to the ESIPT process in polar solvents than in nonpolar solvents. With a decrease in solvent polarity, it was more conducive to the ESIPT process. Our study systematically presents the ESIPT process and different detection mechanisms of the two reversible probe molecules regulated by solvent polarity, providing new insights into the design and development of novel fluorescent probes.

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Turning ON/OFF the fluorescence of the ESIPT state by changing the hydrogen bond distance and orientation in quinoline–pyrazole derivatives

Cited by 14 publications

References 49 publications

Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(ii) complexes with 1-hydroxy-1H-imidazole-based ligands

Tuning ESIPT-coupled luminescence by expanding π-conjugation of a proton acceptor moiety in ESIPT-capable zinc(ii) complexes with 1-hydroxy-1H-imidazole-based ligands

Photophysical Properties of (E)-1-(4-(Diethyla-mino)-2-hydroxybenzylidene)-4,4-dimethylthiosemicarbazide Compound and Its Triple Fluorescence Emission Mechanism: A Theoretical Perspective

Modulating the ESIPT Mechanism and Luminescence Characteristics of Two Reversible Fluorescent Probes by Solvent Polarity: A Novel Perspective

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