Substituent control of photophysical properties for excited-state intramolecular proton transfer (ESIPT) of o-LHBDI derivatives: a TD-DFT investigation

Ni, Mei; Su, Shenyang; Fang, Hua

doi:10.1007/s00894-020-04378-5

Cited by 12 publications

(6 citation statements)

References 62 publications

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“…The analysis of PES curves concludes that the ESIPT process is reversible and 4 and 4‐PT may exist in equilibrium in the S 1 state. [ 76 ] The S 1 geometry of 4D was obtained to study the structural parameters of 4D after photoexcitation. The dihedral angles α (C 16 –N 24 –C 25 –C 26 ) and β (C 12 –C 8 –C 10 −C 15 ) of 4D were twisted by 12.7° and 9.4°, respectively, in the S 1 state in comparison with S 0 (Tables 1 and 3).…”

Section: Resultsmentioning

confidence: 99%

Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

Kediya

Manhas

Jha

2021

J of Physical Organic Chem

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Density functional theory (DFT) and time‐dependent density functional theory (TD‐DFT) methods have been applied to decipher the F− anion sensing mechanism of a fluorescent probe N‐(2‐(benzothiazole‐2‐yl)phenyl)‐4‐methoxybenzamide (4). The amidic proton (N–H) of the selected probe may exhibit an intramolecular hydrogen bond (IMHB) with the nitrogen atom of benzothiazole moiety. The weak IMHB of N24–H26‐‐‐N12 in the excited state favors reverse proton transfer process in 4. In the ground state of 4, the F− anion interacts via F−‐‐‐H–N bond, which immediately deprotonates the amidic proton, leading to the distortion of the geometry. Subsequent to deprotonation, the significant intramolecular charge transfer (ICT) character was observed in 4. On account of the significant ICT process, the redshift in absorption and emission spectra was observed. These outcomes were employed to delineate the sensing mechanism of molecule 4.

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Section: Resultsmentioning

confidence: 99%

Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

Kediya

Manhas

Jha

2021

J of Physical Organic Chem

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“…ESIPT thus provides an alternative approach to traditional intermolecular ESPT methodologies for designing molecules with suitable bioimaging properties. For example, a prototypical ESIPT system can be strategically tuned to alter k ESIPT and to either promote or inhibit N*-form emission, as was the case in altering the acidity of an amine group in the N–H-type ESIPT systems and the phenolic-ring hydroxy group in GFP-chromophore analogues. ,, The typically ultrafast ESIPT rate can be reduced in systems with an N–H···N hydrogen bond, as shown in a synthesized blue fluorescent protein analogue due to its weakened intramolecular H-bond compared to O and S’s stronger H-bond donating and accepting capabilities. , k ESIPT can also be tuned by a substituent to either raise or lower the ESIPT energy barrier ,, or enhance intramolecular charge transfer (ICT) to perturb ESIPT by reducing the acidity of the proton donor and give rise to a charge-transfer emission band , that has been shown to be tunable. ,, Since ESIPT emission is highly sensitive to the environment, a comprehensive solvent-dependent study is warranted.…”

Section: Introductionmentioning

confidence: 99%

“…11,24,25 The typically ultrafast ESIPT rate can be reduced in systems with an N−H•••N hydrogen bond, as shown in a synthesized blue fluorescent protein analogue due to its weakened intramolecular H-bond compared to O and S's stronger H-bond donating and accepting capabilities. 11,26 k ESIPT can also be tuned by a substituent to either raise or lower the ESIPT energy barrier 11,24,25 or enhance intramolecular charge transfer (ICT) to perturb ESIPT by reducing the acidity of the proton donor and give rise to a chargetransfer emission band 9,27 that has been shown to be tunable. 6,28,29 Since ESIPT emission is highly sensitive to the environment, a comprehensive solvent-dependent study is warranted.…”

Section: Introductionmentioning

confidence: 99%

Fluorescence Modulation of ortho-Green Fluorescent Protein Chromophores Following Ultrafast Proton Transfer in Solution

et al. 2022

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Photophysical and photochemical properties of the green fluorescent protein (GFP) chromophore and derivatives underlie their bioimaging applications. To date, ultrafast spectroscopic tools represent the key for unraveling fluorescence mechanisms toward rational design of this powerful biomimetic framework. To correlate the excited-state intramolecular proton transfer (ESIPT) with chromophore emission properties, we implement experimental and computational tool sets to elucidate real-time electronic and structural dynamics of two archetypal ortho-GFP chromophores (o-HBDI and o-LHBDI) possessing an intramolecular hydrogen bond to undergo efficient ESIPT, only differing in a bridge-bond constraint. Using excited-state femtosecond stimulated Raman spectroscopy (FSRS), a low-frequency phenolic (P)-ring-deformation mode (∼562 cm–1) was uncovered to accompany ESIPT. The tautomerized chromophore undergoes either rapid P-ring isomerization to reach the ground state with essentially no fluorescence for o-HBDI or enhanced (up to an impressive 180-fold in acetonitrile) and solvent-polarity-dependent fluorescence by P-ring locking in o-LHBDI. The significant dependence of the fluorescence enhancement ratio on solvent viscosity confirms P-ring isomerization as the dominant nonradiative decay pathway for o-HBDI. This work provides crucial insights into the dynamic solute–solvent electrostatic and steric interactions, enabling the application-specific improvement of ESIPT-capable molecules as versatile fluorescence-based sensors and imaging agents from large Stokes shift emission to brighter probes in physiological environments.

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“…Although these multiconfigurational wavefunction methods have been successfully applied to study photochemical reactions, − these methods are very costly for larger systems, especially in terms of geometry optimization. Time-dependent density functional theory (TDDFT) provides an efficient way to optimize the structures of large systems, and it has been widely used to investigate photochemical processes due to its low cost and excellent performance. − Although the single reference framework of density functional theory (DFT) restricts its application in many cases, TDDFT can well described excited states with a single excitation, such as triplet states or Frank–Condon excitation (FC) . Consequently, in this letter, both DFT and TDDFT are used to investigate the photoinduced [4 + 2] cycloaddition reaction.…”

Section: Introductionmentioning

confidence: 99%

Dearomatization of Benzenoid Arenes Triggered by Triplet Excited State Intramolecular Proton Transfer

Zhou

Zhang

2022

J. Phys. Chem. A

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The detailed mechanism of photoinduced dearomatization of benzenoid arenes is investigated using both the high-level ab initio method and density functional theory. The results suggest that the optically allowed singlet excited state (S 2 ) can quickly decay to the lowest triplet excited state (T 1 ) through a barrierless internal conversion and intersystem crossing. Importantly, we find a triplet excited state intramolecular proton transfer (T-ESIPT) pathway to produce a diradical triplet intermediate ( 3 M O−H ), which can trigger the subsequent [4 + 2] dearomatization reaction. Furthermore, the diastereoselectivity of the reaction was illustrated by the rotation of the O − H group of 3 M O−H , which could be effectively modulated by the solvent effect (arising from the strength of the intermolecular hydrogen bond) and the substituted effect (arising from the strength of the electron-donation group). This photochemical mechanism can explain well the experimental observations, and the novel T-ESIPT process can open a new door in studying the photoinduced proton transfer reactions.

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Substituent control of photophysical properties for excited-state intramolecular proton transfer (ESIPT) of o-LHBDI derivatives: a TD-DFT investigation

Cited by 12 publications

References 62 publications

Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

Benzothiazole‐based chemosensor: a quick dip into its anion sensing mechanism

Fluorescence Modulation of ortho-Green Fluorescent Protein Chromophores Following Ultrafast Proton Transfer in Solution

Dearomatization of Benzenoid Arenes Triggered by Triplet Excited State Intramolecular Proton Transfer

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