S<sub>2</sub> Fluorescence Dynamics of <i>meso</i>‐Aryl‐Substituted Subporphyrins

Sung, Jooyoung; Kim, Pyosang; Saga, Shun; Hayashi, Shinya; Osuka, Atsuhiro; Kim, Dongho

doi:10.1002/ange.201307566

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…In the case of TPP derivatives, the large energy gap between the S 2 and S 1 states causes relatively slow internal conversion, leading to S 2 fluorescence. Similar S 2 fluorescence has been reported for various molecules to date. − Notably, these higher excited states can also be treated as precursor exited states for various reactions. If a reaction is fast enough to compete with the internal conversion, a higher reactivity due to larger excitation energy can be expected.…”

Section: Introductionsupporting

confidence: 76%

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

et al. 2014

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Electron and energy transfer processes from higher excited states are attractive for efficient photoenergy utilization because energy dissipating internal conversion processes can be avoided. In the present study, charge separation processes in meso-substituted Sb- and Ge tetraphenylporphyrins (TPPs) were investigated by means of laser spectroscopy. For both Sb- and GeTPPs, S2- and S1-fluorescence emissions were confirmed. Sb- and GeTPPs containing a meso-substituent with a higher electron donor-ability exhibited charge separation from the S2 state, and this was confirmed by transient absorption spectroscopy and a fluorescence up-conversion method. Charge separation was faster for SbTPP with a donor at the meso position than for SbTPP bearing a donor as an axial ligand. The faster charge separation of the present TPPs was attributed to a larger electronic coupling due to a larger HOMO electron density at the meso-carbon of the porphyrin ring. In addition, the charge separation processes in the present meso-substituted TPPs occurred under the adiabatic condition. Contribution of the intramolecular exciplex to the relaxation process was also indicated for the S1 state of GeTPPs.

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Section: Introductionsupporting

confidence: 76%

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

et al. 2014

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“…64 In addition to the S 1 fluorescence, S 2 fluorescence dynamics of meso-aryl-substituted subporphyrins have been unambiguously investigated by Osuka, Kim, and co-workers. 86 Upon excitation at the Soret band, 9 and its B-phenyl counterpart 59 exhibit fluorescence profiles ranging from 380 to 450 nm, which are mirror images to the Soret band (Figure 15). These fluorescence spectra can, therefore, be assigned to be an S 2 fluorescence.…”

Section: Chemical Reviewsmentioning

confidence: 99%

Recent Advances in Subporphyrins and Triphyrin Analogues: Contracted Porphyrins Comprising Three Pyrrole Rings

2016

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Subporphyrinato boron (subporphyrin) was elusive until the syntheses of tribenzosubporphine in 2006 and meso-aryl-substituted subporphyrin in 2007. These novel contracted analogues possess a 14π-electron conjugated system embedded in a bowl-shaped structure. They exhibit absorption and fluorescence in the UV/vis region and nonlinear optical properties due to their octupolar structures. The unique coordination geometry around the central boron atom in the structure of subporphyrin enabled investigation of rare boron species, such as borenium cations, boron hydrides, and boron peroxides. Along with the burgeoning development of the chemistry of subporphyrins, analogous triphyrin systems have also emerged. Their rich coordination chemistry as a result of their free-base structures, which are different from the boron-coordinating structure of subporphyrins, has been intensively investigated. On the basis of the unique structures and reactivities of subporphyrins and their related triphyrin analogues, supramolecular architectures and covalently linked multicomponent systems have also been actively pursued. This Review provides an overview of the development of subporphyrin and triphyrin chemistry in the past decade and future prospects in this field, which may inspire molecular design toward applications based on their unique properties.

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“…Such S 2 fluorescence from π-conjugated organic molecules has been observed mainly from pyrrolic pigments such as porphyrinoids and boron-dipyrromethane derivatives. 2−9 As representative porphyrinoids, free-base porphyrin, metalloporphyrins, B(III)subporphyrins, 9 and deprotonated [26]hexaphyrins 11 rationalize the detection of their S 2 fluorescences on account of energetically well-separated B-and Q-bands in the absorption spectra (∼5000 cm −1 ), which allows for radiative transition from higher excited states to the ground state to compete with the rapid nonradiative internal conversion to the lowest excited state. 10 In this regard, observation of S 2 fluorescence in the near-IR region would be very difficult because the energy gap between the emitting state and the ground state should be small.…”

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confidence: 99%

Near-Infrared S₂ Fluorescence from Deprotonated Möbius Aromatic [32]Heptaphyrin

Kim

Hong

Kim

et al. 2018

J. Phys. Chem. Lett.

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This study revealed S fluorescence from deprotonated meso-pentafluorophenyl-substituted Möbius aromatic [32]heptaphyrin(1.1.1.1.1.1.1) that was formed upon treatment of neutral antiaromatic [32]heptephyrin with tetrabutylammonium fluoride. Higher excited-state dynamics and emission were studied by fs-transient absorption spectroscopy and a broad-band fluorescence upconversion technique. This is the first S fluorescence from chromophores with twisted Möbius topology, and the observation of S fluorescence in the near-infrared region has been unprecedented. The higher excited-state dynamics of neutral and deprotonated [32]heptaphyrins were compared by ultrafast transient absorption spectroscopy to understand the S fluorescence origin. In the antiaromatic [32]heptaphyrin, a fast time component of 65 fs was assigned as an internal conversion process from the S state to the S state, which occurs prior to relaxation to the optically dark, lowest electronic state (S). Therefore, the S state of the antiaromatic [32]heptaphyrin acts as a trap state intervening radiative transitions from the S state to the S state. In deprotonated [32]heptaphyrin, the internal conversion from the S state to the S state proceeds with a slower time constant of 150 fs for owing to its rigid structure, helping the observation of its S fluorescence.

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S₂ Fluorescence Dynamics of meso‐Aryl‐Substituted Subporphyrins

Cited by 8 publications

References 30 publications

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Recent Advances in Subporphyrins and Triphyrin Analogues: Contracted Porphyrins Comprising Three Pyrrole Rings

Near-Infrared S₂ Fluorescence from Deprotonated Möbius Aromatic [32]Heptaphyrin

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S2 Fluorescence Dynamics of meso‐Aryl‐Substituted Subporphyrins

Cited by 8 publications

References 30 publications

Solvent Dynamics Regulated Electron Transfer in S2-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Solvent Dynamics Regulated Electron Transfer in S2-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Recent Advances in Subporphyrins and Triphyrin Analogues: Contracted Porphyrins Comprising Three Pyrrole Rings

Near-Infrared S2 Fluorescence from Deprotonated Möbius Aromatic [32]Heptaphyrin

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S₂ Fluorescence Dynamics of meso‐Aryl‐Substituted Subporphyrins

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Solvent Dynamics Regulated Electron Transfer in S₂-Excited Sb and Ge Tetraphenylporphyrins with an Electron Donor Substituent at the Meso-Position

Near-Infrared S₂ Fluorescence from Deprotonated Möbius Aromatic [32]Heptaphyrin