Photochemical synthesis and photophysical properties of coumarins bearing extended polyaromatic rings studied by emission and transient absorption measurements

Minoru Yamaji, Yuma Hakoda, Hideki Okamoto, Fumito Tani

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Abstract

We prepared a variety of coumarin derivatives having expanded π-electron systems along the direction crossing the C3-C4 bond of the coumarin skeleton via a photochemical cyclization process and investigated their photophysical features as a function of the number (n) of the added benzene rings based on emission and transient absorption measurements. Upon increasing n, the fluorescence quantum yields of the π-extended coumarins increased. Expanding the π-electron system on the C3-C4 bond of the coumarin skeleton was found to be efficient for increasing the fluorescence ability more than that on the C7-C8 bond. Introducing the methoxy group at the 7-position was also efficient for enhancing the fluorescence quantum yield and rate of the expanded coumarins. The non-radiative process from the fluorescence state was not substantially influenced by the expanded π-electron system. The competitive process with the fluorescence was found to be intersystem crossing to the triplet state based on the observations of the triplet-triplet absorption. The effects of the expanded π-electron systems on the fluorescence ability were investigated with the aid of TD-DFT calculations.

Original languageEnglish
Pages (from-to)555-563
Number of pages9
JournalPhotochemical and Photobiological Sciences
Volume16
Issue number4
DOIs
Publication statusPublished - 2017

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Bearings (structural)
Coumarins
Fluorescence
fluorescence
rings
synthesis
Electrons
Quantum yield
musculoskeletal system
electrons
Cyclization
Benzene
Discrete Fourier transforms
atomic energy levels
benzene

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

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title = "Photochemical synthesis and photophysical properties of coumarins bearing extended polyaromatic rings studied by emission and transient absorption measurements",
abstract = "We prepared a variety of coumarin derivatives having expanded π-electron systems along the direction crossing the C3-C4 bond of the coumarin skeleton via a photochemical cyclization process and investigated their photophysical features as a function of the number (n) of the added benzene rings based on emission and transient absorption measurements. Upon increasing n, the fluorescence quantum yields of the π-extended coumarins increased. Expanding the π-electron system on the C3-C4 bond of the coumarin skeleton was found to be efficient for increasing the fluorescence ability more than that on the C7-C8 bond. Introducing the methoxy group at the 7-position was also efficient for enhancing the fluorescence quantum yield and rate of the expanded coumarins. The non-radiative process from the fluorescence state was not substantially influenced by the expanded π-electron system. The competitive process with the fluorescence was found to be intersystem crossing to the triplet state based on the observations of the triplet-triplet absorption. The effects of the expanded π-electron systems on the fluorescence ability were investigated with the aid of TD-DFT calculations.",
author = "Minoru Yamaji and Yuma Hakoda and Hideki Okamoto and Fumito Tani",
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TY - JOUR

T1 - Photochemical synthesis and photophysical properties of coumarins bearing extended polyaromatic rings studied by emission and transient absorption measurements

AU - Yamaji, Minoru

AU - Hakoda, Yuma

AU - Okamoto, Hideki

AU - Tani, Fumito

PY - 2017

Y1 - 2017

N2 - We prepared a variety of coumarin derivatives having expanded π-electron systems along the direction crossing the C3-C4 bond of the coumarin skeleton via a photochemical cyclization process and investigated their photophysical features as a function of the number (n) of the added benzene rings based on emission and transient absorption measurements. Upon increasing n, the fluorescence quantum yields of the π-extended coumarins increased. Expanding the π-electron system on the C3-C4 bond of the coumarin skeleton was found to be efficient for increasing the fluorescence ability more than that on the C7-C8 bond. Introducing the methoxy group at the 7-position was also efficient for enhancing the fluorescence quantum yield and rate of the expanded coumarins. The non-radiative process from the fluorescence state was not substantially influenced by the expanded π-electron system. The competitive process with the fluorescence was found to be intersystem crossing to the triplet state based on the observations of the triplet-triplet absorption. The effects of the expanded π-electron systems on the fluorescence ability were investigated with the aid of TD-DFT calculations.

AB - We prepared a variety of coumarin derivatives having expanded π-electron systems along the direction crossing the C3-C4 bond of the coumarin skeleton via a photochemical cyclization process and investigated their photophysical features as a function of the number (n) of the added benzene rings based on emission and transient absorption measurements. Upon increasing n, the fluorescence quantum yields of the π-extended coumarins increased. Expanding the π-electron system on the C3-C4 bond of the coumarin skeleton was found to be efficient for increasing the fluorescence ability more than that on the C7-C8 bond. Introducing the methoxy group at the 7-position was also efficient for enhancing the fluorescence quantum yield and rate of the expanded coumarins. The non-radiative process from the fluorescence state was not substantially influenced by the expanded π-electron system. The competitive process with the fluorescence was found to be intersystem crossing to the triplet state based on the observations of the triplet-triplet absorption. The effects of the expanded π-electron systems on the fluorescence ability were investigated with the aid of TD-DFT calculations.

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DO - 10.1039/C6PP00399K

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