An abnormally slow proton transfer reaction in a simple HBO derivative due to ultrafast intramolecular-charge transfer events

Alarcos, Noemí; Gutiérrez, Mario; Liras, Marta; Sánchez, Félix; Douhal, Abderrazzak

doi:10.1039/c5cp00577a

Cited by 58 publications

(84 citation statements)

References 68 publications

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“…Alarcos et al have experimentally measured the steady‐state spectra of 6A‐HBO . We present here our calculated absorption and fluorescence spectra of 6A‐HBO using the same solvents.…”

Section: Resultsmentioning

confidence: 99%

“…We present here our calculated absorption and fluorescence spectra of 6A‐HBO using the same solvents. As can be seen from Figure , the absorption spectra in different solvents were simulated, and the maximum absorption peaks agree well with their corresponding experimental results . In addition, there are two independent fluorescence spectra (shown in Figure ) originating from the calculated first singlet excited state of 6A‐HBO‐enol and 6A‐HBO‐keto form, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…The 6A‐HBO‐enol spectrum in MeOH displays an emission peak with a normal Stokes shift at 441 nm and a fluorescence peak with a larger shift at 470.4 nm for the geometry‐relaxed 6A‐HBO‐keto. This fluorescence peak is consistent well with the experimental value of 470 nm in MeOH . Analogously, the fluorescence spectra of 6A‐HBO‐enol in other three solvents ( n ‐heptane, DCM, and ACN) show a normal Stokes shift at 399.8, 431.2, and 441 nm, respectively.…”

Section: Resultsmentioning

confidence: 99%

“…6A‐HBO and its derivatives with intrinsic PT properties have been widely used as luminescent materials for pH and biologically relevant anions or chemical sensing of cations . 6A‐HBO is one of the most‐studied systems for explaining the dynamics and mechanism of the intramolecular PT process . Gutierrez et al report proton motion coupled to charge transfer reactions based on time‐resolved emission studies .…”

Section: Introductionmentioning

confidence: 99%

“…Cukier et al and Hammes‐Schiffer et al have performed theoretical studies in the issue of coupled electron and proton transfer . To better explain the behavior of 6A‐HBO, Alarcos et al studied the photodynamics in different polar solvents, demonstrating that the ESIPT reaction follows the intramolecular charge transfer (ICT) reaction and is solvent dependent …”

Section: Introductionmentioning

confidence: 99%

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Excited‐state intramolecular proton transfer of 6‐amino‐2‐(2′‐hydroxyphenyl) benzoxazole (6A‐HBO) in different solvents

Zhou

Zhang

et al. 2018

J of Physical Organic Chem

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The excited‐state intramolecular proton transfer (ESIPT) process of 6‐amino‐2‐(2′‐hydroxyphenyl) benzoxazole (6A‐HBO) was investigated using density functional theory and time‐dependent density functional theory methods with B3LYP and TZVP basis sets. n‐Heptane, dichloromethane, methanol, and acetonitrile were chosen as a series of polar solvents in calculations using the IEFPCM model. To obtain a more comprehensive ESIPT mechanism, we constructed the S0 and S1 states' potential energy surfaces (PESs) by incrementally twisting the ─OH bond and increasing the distance of O–H bond. Based on the analysis of the bond lengths, the IR vibrational spectra, and the frontier molecular orbits (MOs), the intramolecular hydrogen bonding (O─H...N) is clearly strengthened, and the charge is redistributed in the S1 state. The results of calculated absorption spectrum are in accord with the experimental data. The fluorescence spectrum of 6A‐HBO‐enol showed a normal red shift, but the red shift of the 6A‐HBO‐keto is larger and increases with the solvent polarity, indicating a charge transfer. Analysis of the PESs indicates a lower potential energy barrier in S1 state for the proton transfer from the O atom to the N atom, with the excited state potential barrier slightly decreasing with the increase of the solvent polarity.

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“…Alarcos et al have experimentally measured the steady‐state spectra of 6A‐HBO . We present here our calculated absorption and fluorescence spectra of 6A‐HBO using the same solvents.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Excited‐state intramolecular proton transfer of 6‐amino‐2‐(2′‐hydroxyphenyl) benzoxazole (6A‐HBO) in different solvents

Zhou

Zhang

et al. 2018

J of Physical Organic Chem

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Unexpected Sole Enol‐Form Emission of 2‐(2′‐Hydroxyphenyl)oxazoles for Highly Efficient Deep‐Blue‐Emitting Organic Electroluminescent Devices

Tang

Zhou

et al. 2017

Adv Funct Materials

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Considerable efforts have been devoted to the development of highly efficient blue light‐emitting materials. However, deep‐blue fluorescence materials that can satisfy the Commission Internationale de l'Eclairage (CIE) coordinates of (0.14, 0.08) of the National Television System Committee (NTSC) standard blue and, moreover, possess a high external quantum efficiency (EQE) over 5%, remain scarce. Here, the unusual luminescence properties of triphenylamine‐bearing 2‐(2′‐hydroxyphenyl)oxazoles (3a–3c) and their applications in organic light‐emitting diodes (OLEDs) are reported as highly efficient deep‐blue emitters. The 3a‐based device exhibits a high spectral stability and an excellent color purity with a narrow full‐width at half‐maximum of 53 nm and the CIE coordinates of (0.15, 0.08), which is very close to the NTSC standard blue. The exciton utilization of the device closes to 100%, exceeding the theoretical limit of 25% in conventional fluorescent OLEDs. Experimental data and theoretical calculations demonstrate that 3a possesses a highly hybridized local and charge‐transfer excited state character. In OLEDs, 3a exhibits a maximum luminance of 9054 cd m−2 and an EQE up to 7.1%, which is the first example of highly efficient blue OLEDs based on the sole enol‐form emission of 2‐(2′‐hydroxyphenyl)azoles.

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Competitive Excimer Formation and Energy Transfer in Zr‐Based Heterolinker Metal–Organic Frameworks

Gutiérrez

Sánchez

Douhal

2016

Chemistry A European J

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The spectroscopy and dynamics of a series of Zr-based MOFs in dichloromethane suspension are reported. These Zr-NADC MOFs were constructed by using different mixtures of 2,6-naphthalenedicarboxylate (NDC) and 4-amino-2,6-naphthalenedicarboxylate (NADC) as organic linkers. The fraction of NADC relative to NDC in these heterolinker MOFs ranges from 2 to 35 %. The results indicate two competitive photoprocesses: NDC excimer formation and an energy transfer (ET) from excited NDC linkers to NADC linkers. Increasing the fraction of NADC linkers in the Zr-NADC nanostructure decreases the mean time constant of NDC excimer formation, while the NADC emission intensity experiences a drop at the highest fraction of this linker in the MOF. The first observation is explained by an increase in the energy-transfer probability between the two linkers, and the second by emission quenching in the NADC linkers due to ultrafast charge transfer assisted by the amino group. Femtosecond time-resolved emission studies showed that the ET process (recorded as decaying and rising components) from excited NDC to NADC takes place in 1.2 ps. Direct excitation of the NADC linkers (at 410 nm) shows a decaying, but not rising, component of 250-480 fs, which could reflect the formation of a nonemissive charge-separation state. The results show that by using MOFs having heterolinkers it is possible to trigger and tune excimer formation and ET processes.

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An abnormally slow proton transfer reaction in a simple HBO derivative due to ultrafast intramolecular-charge transfer events

Abstract: Stepwise and coupled photoinduced ICT and ESIPT reactions in a simple derivative of HBO in solution.

Cited by 58 publications

References 68 publications

Excited‐state intramolecular proton transfer of 6‐amino‐2‐(2′‐hydroxyphenyl) benzoxazole (6A‐HBO) in different solvents

Excited‐state intramolecular proton transfer of 6‐amino‐2‐(2′‐hydroxyphenyl) benzoxazole (6A‐HBO) in different solvents

Unexpected Sole Enol‐Form Emission of 2‐(2′‐Hydroxyphenyl)oxazoles for Highly Efficient Deep‐Blue‐Emitting Organic Electroluminescent Devices

Competitive Excimer Formation and Energy Transfer in Zr‐Based Heterolinker Metal–Organic Frameworks

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