Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1)

Dongho Kim, Jung Ho Kwon, Tae Kyu Ahn, Min Chul Yoon, Deok Yun Kim, Mi Kyoung Koh, Hiroyuki Furuta, Masaakl Suzuki, Atsuhiro Osuka

Research output: Contribution to journalArticle

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Abstract

We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (π,π*) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and π-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 ± 0.3 ps and 670 fs, respectively, than those (267 ± 16 and 62.4 ± 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (σ(2)) values, which are believed to depend strongly on the ring planarity (π-conjugation), are in line with the excited-state lifetime trends.

Original languageEnglish
Pages (from-to)11683-11690
Number of pages8
JournalJournal of Physical Chemistry B
Volume110
Issue number24
DOIs
Publication statusPublished - 2006 Jun 22

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Excited states
Absorption spectra
Photons
Metals
rings
Porphyrins
Electron transitions
absorption spectra
orbitals
life (durability)
Fluorescence
photons
conjugation
porphyrins
metals
absorption cross sections
excitation
Geometry
Electrons
trends

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Kim, Dongho ; Kwon, Jung Ho ; Ahn, Tae Kyu ; Yoon, Min Chul ; Kim, Deok Yun ; Koh, Mi Kyoung ; Furuta, Hiroyuki ; Suzuki, Masaakl ; Osuka, Atsuhiro. / Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1). In: Journal of Physical Chemistry B. 2006 ; Vol. 110, No. 24. pp. 11683-11690.
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abstract = "We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (π,π*) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and π-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 ± 0.3 ps and 670 fs, respectively, than those (267 ± 16 and 62.4 ± 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (σ(2)) values, which are believed to depend strongly on the ring planarity (π-conjugation), are in line with the excited-state lifetime trends.",
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Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1). / Kim, Dongho; Kwon, Jung Ho; Ahn, Tae Kyu; Yoon, Min Chul; Kim, Deok Yun; Koh, Mi Kyoung; Furuta, Hiroyuki; Suzuki, Masaakl; Osuka, Atsuhiro.

In: Journal of Physical Chemistry B, Vol. 110, No. 24, 22.06.2006, p. 11683-11690.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Comparative photophysical properties of free-base, bis-Zn(II), bis-Cu(II), and bis-Co(II) doubly N-confused hexaphyrins(1.1.1.1.1.1)

AU - Kim, Dongho

AU - Kwon, Jung Ho

AU - Ahn, Tae Kyu

AU - Yoon, Min Chul

AU - Kim, Deok Yun

AU - Koh, Mi Kyoung

AU - Furuta, Hiroyuki

AU - Suzuki, Masaakl

AU - Osuka, Atsuhiro

PY - 2006/6/22

Y1 - 2006/6/22

N2 - We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (π,π*) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and π-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 ± 0.3 ps and 670 fs, respectively, than those (267 ± 16 and 62.4 ± 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (σ(2)) values, which are believed to depend strongly on the ring planarity (π-conjugation), are in line with the excited-state lifetime trends.

AB - We have comparatively investigated the photophysics of a series of bis-metal doubly N-confused hexaphyrins(1.1.1.1.1.1) using time-resolved fluorescence, femtosecond transient absorption, two-photon absorption measurements, and geometry-optimized ab initio calculations. Bis-Zn(II) and free-base doubly N-confused hexaphyrins exhibit well-resolved and red-shifted B- and Q-like absorption bands compared with porphyrins. Their allowed transitions are (π,π*) transitions of the hexaphyrin ring, as confirmed by the HOMO and LUMO frontier orbitals based on ab initio calculations at the B3LYP/6-31G level. On the other hand, the absorption spectra of bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins are relatively broad, presumably due to large couplings between the metal d-orbitals and π-electrons of the hexaphyrin ring. Owing to these couplings, bis-Cu(II) and bis-Co(II) doubly N-confused hexaphyrins have much shorter excited-state lifetimes of 9.4 ± 0.3 ps and 670 fs, respectively, than those (267 ± 16 and 62.4 ± 1.2 ps, respectively) of bis-Zn(II) and free-base doubly N-confused hexaphyrins. The two-photon absorption cross section (σ(2)) values, which are believed to depend strongly on the ring planarity (π-conjugation), are in line with the excited-state lifetime trends.

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