Time-resolved electron spin resonance of gallium and germanium porphyrins in the excited triplet state

Kazuyuki Ishii, Satoko Abiko, Nagao Kobayashi

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T(1x) and T(1y) sublevels is faster than that to the T(1z) sublevel (T(1x), T(1y), and T(1z) are sublevels of the T1 state), while the ISC of ZnTPP and Ga-(TPP)(OH) is selective to the T(1z) sublevel. This is interpreted by a weak interaction between the d(π) orbital of germanium and LUMO (e(g)) of the porphyrin ligand, resulting in small spin-orbit coupling (SOC). The interpretation is supported by molecular orbital calculations. The ISC of Ge(OEP)(OH)2 (OEP = dianion of octaethylporphyrin) and Ge(Pc)(OH)2 (Pc = dianion of tetra-tert-butylphthalocyanine) is found to be selective to the T(1z) sublevel in contrast to Ge(TPP)(OH)2. This dependence on the porphyrin ligand is reasonably explained by a difference between the 3(a(1u)e(g)) (the OEP and Pc complexes) and 3(a(2u)e(g)) (the TPP complex) configurations. This is the first observation of a difference in selective ISC between the 3(a(1u)e(g)) and 3(a(2u)e(g)) configurations. The TRESR spectrum of Ge(TPP)Br2 is different from those of Ge(TPP)Cl2 and Ge(TPP)(OH)2, and is interpreted by SOC between the T1 and T2 states. From ESR parameters the square of the coefficient of the e(g) orbital on bromine is evaluated as 0.018 in the T1 state.

Original languageEnglish
Pages (from-to)468-472
Number of pages5
JournalInorganic Chemistry
Volume39
Issue number3
DOIs
Publication statusPublished - 2000 Feb 7
Externally publishedYes

Fingerprint

Germanium
Gallium
Porphyrins
Excited states
porphyrins
atomic energy levels
gallium
Paramagnetic resonance
germanium
electron paramagnetic resonance
Orbits
Ligands
orbits
Bromine
orbitals
Orbital calculations
ligands
Molecular orbitals
bromine
configurations

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Time-resolved electron spin resonance of gallium and germanium porphyrins in the excited triplet state. / Ishii, Kazuyuki; Abiko, Satoko; Kobayashi, Nagao.

In: Inorganic Chemistry, Vol. 39, No. 3, 07.02.2000, p. 468-472.

Research output: Contribution to journalArticle

@article{84383387d62a43f08ec46e9d6cd7d418,
title = "Time-resolved electron spin resonance of gallium and germanium porphyrins in the excited triplet state",
abstract = "Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T(1x) and T(1y) sublevels is faster than that to the T(1z) sublevel (T(1x), T(1y), and T(1z) are sublevels of the T1 state), while the ISC of ZnTPP and Ga-(TPP)(OH) is selective to the T(1z) sublevel. This is interpreted by a weak interaction between the d(π) orbital of germanium and LUMO (e(g)) of the porphyrin ligand, resulting in small spin-orbit coupling (SOC). The interpretation is supported by molecular orbital calculations. The ISC of Ge(OEP)(OH)2 (OEP = dianion of octaethylporphyrin) and Ge(Pc)(OH)2 (Pc = dianion of tetra-tert-butylphthalocyanine) is found to be selective to the T(1z) sublevel in contrast to Ge(TPP)(OH)2. This dependence on the porphyrin ligand is reasonably explained by a difference between the 3(a(1u)e(g)) (the OEP and Pc complexes) and 3(a(2u)e(g)) (the TPP complex) configurations. This is the first observation of a difference in selective ISC between the 3(a(1u)e(g)) and 3(a(2u)e(g)) configurations. The TRESR spectrum of Ge(TPP)Br2 is different from those of Ge(TPP)Cl2 and Ge(TPP)(OH)2, and is interpreted by SOC between the T1 and T2 states. From ESR parameters the square of the coefficient of the e(g) orbital on bromine is evaluated as 0.018 in the T1 state.",
author = "Kazuyuki Ishii and Satoko Abiko and Nagao Kobayashi",
year = "2000",
month = "2",
day = "7",
doi = "10.1021/ic990783t",
language = "English",
volume = "39",
pages = "468--472",
journal = "Inorganic Chemistry",
issn = "0020-1669",
publisher = "American Chemical Society",
number = "3",

}

TY - JOUR

T1 - Time-resolved electron spin resonance of gallium and germanium porphyrins in the excited triplet state

AU - Ishii, Kazuyuki

AU - Abiko, Satoko

AU - Kobayashi, Nagao

PY - 2000/2/7

Y1 - 2000/2/7

N2 - Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T(1x) and T(1y) sublevels is faster than that to the T(1z) sublevel (T(1x), T(1y), and T(1z) are sublevels of the T1 state), while the ISC of ZnTPP and Ga-(TPP)(OH) is selective to the T(1z) sublevel. This is interpreted by a weak interaction between the d(π) orbital of germanium and LUMO (e(g)) of the porphyrin ligand, resulting in small spin-orbit coupling (SOC). The interpretation is supported by molecular orbital calculations. The ISC of Ge(OEP)(OH)2 (OEP = dianion of octaethylporphyrin) and Ge(Pc)(OH)2 (Pc = dianion of tetra-tert-butylphthalocyanine) is found to be selective to the T(1z) sublevel in contrast to Ge(TPP)(OH)2. This dependence on the porphyrin ligand is reasonably explained by a difference between the 3(a(1u)e(g)) (the OEP and Pc complexes) and 3(a(2u)e(g)) (the TPP complex) configurations. This is the first observation of a difference in selective ISC between the 3(a(1u)e(g)) and 3(a(2u)e(g)) configurations. The TRESR spectrum of Ge(TPP)Br2 is different from those of Ge(TPP)Cl2 and Ge(TPP)(OH)2, and is interpreted by SOC between the T1 and T2 states. From ESR parameters the square of the coefficient of the e(g) orbital on bromine is evaluated as 0.018 in the T1 state.

AB - Gallium and germanium porphyrin complexes in the lowest excited triplet (T1) state have been studied by time-resolved electron spin resonance (TRESR). It is found that for Ge(TPP)(OH)2 (TPP = dianion of tetraphenylporphyrin) intersystem crossing (ISC) from the lowest excited singlet (S1) state to the T(1x) and T(1y) sublevels is faster than that to the T(1z) sublevel (T(1x), T(1y), and T(1z) are sublevels of the T1 state), while the ISC of ZnTPP and Ga-(TPP)(OH) is selective to the T(1z) sublevel. This is interpreted by a weak interaction between the d(π) orbital of germanium and LUMO (e(g)) of the porphyrin ligand, resulting in small spin-orbit coupling (SOC). The interpretation is supported by molecular orbital calculations. The ISC of Ge(OEP)(OH)2 (OEP = dianion of octaethylporphyrin) and Ge(Pc)(OH)2 (Pc = dianion of tetra-tert-butylphthalocyanine) is found to be selective to the T(1z) sublevel in contrast to Ge(TPP)(OH)2. This dependence on the porphyrin ligand is reasonably explained by a difference between the 3(a(1u)e(g)) (the OEP and Pc complexes) and 3(a(2u)e(g)) (the TPP complex) configurations. This is the first observation of a difference in selective ISC between the 3(a(1u)e(g)) and 3(a(2u)e(g)) configurations. The TRESR spectrum of Ge(TPP)Br2 is different from those of Ge(TPP)Cl2 and Ge(TPP)(OH)2, and is interpreted by SOC between the T1 and T2 states. From ESR parameters the square of the coefficient of the e(g) orbital on bromine is evaluated as 0.018 in the T1 state.

UR - http://www.scopus.com/inward/record.url?scp=0034614872&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0034614872&partnerID=8YFLogxK

U2 - 10.1021/ic990783t

DO - 10.1021/ic990783t

M3 - Article

C2 - 11229564

AN - SCOPUS:0034614872

VL - 39

SP - 468

EP - 472

JO - Inorganic Chemistry

JF - Inorganic Chemistry

SN - 0020-1669

IS - 3

ER -