Triplet state generation followed by the excited-state intramolecular proton transfer in 3-sulfanylchromen-4-one

Bera, Anshuman; Vennapusa, Sivaranjana Reddy

doi:10.1016/j.jphotochem.2023.114700

Cited by 5 publications

(3 citation statements)

References 30 publications

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“…21–31 Furthermore, the emission of ESIPT-dyes often involves triplet excited states, giving rise to phosphorescence (including room temperature phosphorescence) and thermally-activated delayed fluorescence. 32–41 This plethora of emissive excited states makes ESIPT-capable compounds an appealing platform for the design of multicolor luminescent materials. 42…”

Section: Introductionmentioning

confidence: 99%

“…[21][22][23][24][25][26][27][28][29][30][31] Furthermore, the emission of ESIPT-dyes often involves triplet excited states, giving rise to phosphorescence (including room temperature phosphorescence) and thermally-activated delayed fluorescence. [32][33][34][35][36][37][38][39][40][41] This plethora of emissive excited states makes ESIPT-capable compounds an appealing platform for the design of multicolor luminescent materials. 42 The emission of ESIPT-capable dyes is highly sensitive to solvents, [43][44][45][46][47][48][49][50] substitution in the ESIPT-dye core, protonation/deprotonation, [72][73][74][75][76][77][78][79][80] and coordination of metal ions.…”

Section: Introductionmentioning

confidence: 99%

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Luminescence of ESIPT-capable zinc(ii) complexes with a 1-hydroxy-1H-imidazole-based ligand: exploring the impact of substitution in the proton-donating moiety

et al. 2023

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Luminescence of ESIPT-capable zinc(ii) complexes with a 1-hydroxy-1H-imidazole-based ligand: exploring the impact of substitution in the proton-donating moiety

et al. 2023

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“…Kinetic barriers between the minima of the normal and tautomeric forms in the excited state can partially or fully suppress the proton transfer process and lead to the emission of the normal form. If the barriers separating the normal and tautomeric forms in the excited state are surmountable, ESIPT-capable compounds can show dual emissions associated with the fluorescence of both forms. − Along with singlet-to-singlet transitions, these molecules can be converted to the ground state through triplet excited states and triplet-to-singlet transitions such as phosphorescence (including room temperature phosphorescence) ,,− and thermally activated delayed fluorescence. − Some ESIPT-capable compounds exhibit anti-Kasha emissions, which can be observed in molecules wherein the first and the second excited states are separated by large energy gaps. − …”

Section: Introductionmentioning

confidence: 99%

Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

Shekhovtsov,

Vorob’eva,

Nikolaenkova

et al. 2023

Inorg. Chem.

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A rare example of pyrimidine-based ESIPT-capable compounds, 2-(2-hydroxyphenyl)-4-(1H-pyrazol-1-yl)-6-methylpyrimidine (HL H ), was synthesized (ESIPT�excited state intramolecular proton transfer). Its reactions with zinc(II) salts under basic or acidic conditions afforded a dinuclear [Zn 2 L H 2 Cl 2 ] complex and an ionic (H 2 L H ) 4 [ZnCl 4 ] 2 • 3H 2 O solid. Another ionic solid, (H 2 L H )Br, was obtained from the solution of HL H acidified with HBr. In both ionic solids, the H + ion protonates the same pyrimidinic N atom that accepts the O−H•••N intramolecular hydrogen bond in the structure of free HL H , which breaks this hydrogen bond and switches off ESIPT in these compounds. This series of compounds which includes neutral HL H molecules and ionic (L H ) − and (H 2 L H ) + species allowed us to elucidate the impact of protonation and coordination coupled deprotonation of HL H on the photoluminescence response and on altering the emission mechanism. The neutral HL H compound exhibits yellow emission as a result of the coexistence of two radiative decay channels: (i) T 1 → S 0 phosphorescence of the enol form and (ii) anti-Kasha S 2 → S 0 fluorescence of the keto form, which if feasible due to the large S 2 −S 1 energy gap. However, owing to the efficient nonradiative decay through an energetically favorable conical intersection, the photoluminescence quantum yield of HL H is low. Protonation or deprotonation of the HL H ligand results in the significant blue-shift of the emission bands by more than 100 nm and boosts the quantum efficiency up to ca. 20% in the case ofand (H 2 L H )Br have the same (H 2 L H ) + cation in the structures, their emission properties differ significantly, whereas (H 2 L H )Br shows dual emission associated with two radiative decay channels: (i) S 1 → S 0 fluorescence and (ii) T 1 → S 0 phosphorescence, (H 2 L H ) 4 [ZnCl 4 ] 2 •3H 2 O exhibits only fluorescence. This difference in the emission properties can be associated with the external heavy atom effect in (H 2 L H )Br, which leads to faster intersystem crossing in this compound. Finally, a huge increase in the intensity of the phosphorescence of (H 2 L H )Br on cooling leads to pronounced luminescence thermochromism (violet emission at 300 K, sky-blue emission at 77 K).

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Tuning the Triplet Formation Efficiency by Heavy‐Atom Substitution in 3‐Hydroxythiochromone

Bera,

Nair,

Siraj

et al. 2024

Int J of Quantum Chemistry

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We theoretically studied the triplet formation efficiency in positional isomers of bromine‐substituted 3‐Hydroxythiochromones. Dynamics simulations with relevant spin‐orbit coupling parameters show ultrafast triplet formation with S1 as the donor singlet and upper triplet excited states as receiver states. The near‐degeneracy of S2 with S1 promotes nonadiabatic population transfer from S1 to S2 in isomers with bromine substitution at the 5th position of the parent molecule. This population transfer unfurls an additional intersystem crossing pathway involving S2 and T4, enabling this isomer to show a higher triplet efficiency. The excited‐state intramolecular proton transfer process, promoted by low barrier energy, is operative and can affect the isomers' triplet formation efficiency. Moreover, the timescales of proton transfer and triplet formation can overlap, necessitating thorough experimental investigations to uncover the competitiveness of these simultaneous events.

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Triplet state generation followed by the excited-state intramolecular proton transfer in 3-sulfanylchromen-4-one

Cited by 5 publications

References 30 publications

Luminescence of ESIPT-capable zinc(ii) complexes with a 1-hydroxy-1H-imidazole-based ligand: exploring the impact of substitution in the proton-donating moiety

Luminescence of ESIPT-capable zinc(ii) complexes with a 1-hydroxy-1H-imidazole-based ligand: exploring the impact of substitution in the proton-donating moiety

Complexes on the Base of a Proton Transfer Capable Pyrimidine Derivative: How Protonation and Deprotonation Switch Emission Mechanisms

Tuning the Triplet Formation Efficiency by Heavy‐Atom Substitution in 3‐Hydroxythiochromone

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