Substitution effect of hydroxyl group on photophysical properties of tetraphenylporphyrin (H2TPP) and germanium(IV) tetraphenylporphyrin dichloride (Ge(IV)TPPCl2)

Jeong Hyon Ha, Seung Il Yoo, Gook Young Jung, Insook Rhee Paeng, Yong Rok Kim

Research output: Contribution to journalArticle

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Abstract

Photophysical properties of tetraphenylporphyrin (H2TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH)4TPPH2), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl2), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH)4TPPCl2) have been investigated to elucidate the effects of para OH substituents on the free-base and the metal-incorporated porphyrin π systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended π-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and fluorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced π-conjugation between phenyl ring and porphyrin π-electron system in the ground and the excited states. Such π-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced π-electron interaction of the OH-substituted derivatives in the excited state shortened the fluorescence lifetimes but increased the fluorescence quantum yields since the radiative rate was enhanced more than the fluorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive π-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin-orbit coupling and, consequently, reduced the fluorescence lifetimes and quantum yields. However, the spin-orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive π-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion.

Original languageEnglish
Pages (from-to)189-195
Number of pages7
JournalJournal of Molecular Structure
Volume606
Issue number1-3
DOIs
Publication statusPublished - 2002 Mar 27

Fingerprint

Germanium
Porphyrins
Hydroxyl Radical
Excited states
Substitution reactions
Metalloporphyrins
Fluorescence
Quantum yield
Derivatives
Orbits
Metals
Electrons
tetraphenylporphyrin
Charge transfer
Atoms
hydroxide ion

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry
  • Spectroscopy
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

@article{775639989e7b4a87882e5354ad7b6792,
title = "Substitution effect of hydroxyl group on photophysical properties of tetraphenylporphyrin (H2TPP) and germanium(IV) tetraphenylporphyrin dichloride (Ge(IV)TPPCl2)",
abstract = "Photophysical properties of tetraphenylporphyrin (H2TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH)4TPPH2), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl2), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH)4TPPCl2) have been investigated to elucidate the effects of para OH substituents on the free-base and the metal-incorporated porphyrin π systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended π-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and fluorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced π-conjugation between phenyl ring and porphyrin π-electron system in the ground and the excited states. Such π-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced π-electron interaction of the OH-substituted derivatives in the excited state shortened the fluorescence lifetimes but increased the fluorescence quantum yields since the radiative rate was enhanced more than the fluorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive π-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin-orbit coupling and, consequently, reduced the fluorescence lifetimes and quantum yields. However, the spin-orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive π-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion.",
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Substitution effect of hydroxyl group on photophysical properties of tetraphenylporphyrin (H2TPP) and germanium(IV) tetraphenylporphyrin dichloride (Ge(IV)TPPCl2). / Ha, Jeong Hyon; Yoo, Seung Il; Jung, Gook Young; Paeng, Insook Rhee; Kim, Yong Rok.

In: Journal of Molecular Structure, Vol. 606, No. 1-3, 27.03.2002, p. 189-195.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Substitution effect of hydroxyl group on photophysical properties of tetraphenylporphyrin (H2TPP) and germanium(IV) tetraphenylporphyrin dichloride (Ge(IV)TPPCl2)

AU - Ha, Jeong Hyon

AU - Yoo, Seung Il

AU - Jung, Gook Young

AU - Paeng, Insook Rhee

AU - Kim, Yong Rok

PY - 2002/3/27

Y1 - 2002/3/27

N2 - Photophysical properties of tetraphenylporphyrin (H2TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH)4TPPH2), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl2), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH)4TPPCl2) have been investigated to elucidate the effects of para OH substituents on the free-base and the metal-incorporated porphyrin π systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended π-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and fluorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced π-conjugation between phenyl ring and porphyrin π-electron system in the ground and the excited states. Such π-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced π-electron interaction of the OH-substituted derivatives in the excited state shortened the fluorescence lifetimes but increased the fluorescence quantum yields since the radiative rate was enhanced more than the fluorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive π-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin-orbit coupling and, consequently, reduced the fluorescence lifetimes and quantum yields. However, the spin-orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive π-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion.

AB - Photophysical properties of tetraphenylporphyrin (H2TPP), tetra(p-hydroxyphenyl)porphyrin ((p-OH)4TPPH2), germanium(IV) tetraphenylporphyrin dichloride (GeTPPCl2), and germanium(IV) tetra(p-hydroxyphenyl)porphyrin dichloride (Ge(p-OH)4TPPCl2) have been investigated to elucidate the effects of para OH substituents on the free-base and the metal-incorporated porphyrin π systems by steady-state and time-resolved spectroscopic methods. The observed photophysical properties were correlated with various molecular aspects, such as extended π-conjugation, nonplanar structural distortion, and central heavy atoms. Changes to steady-state absorption and fluorescence spectral characteristics of the OH-substituted porphyrin derivatives were attributed to the enhanced π-conjugation between phenyl ring and porphyrin π-electron system in the ground and the excited states. Such π-conjugation effects of the OH-substituted derivatives are greater when Ge(IV) is introduced into the core. The enhanced π-electron interaction of the OH-substituted derivatives in the excited state shortened the fluorescence lifetimes but increased the fluorescence quantum yields since the radiative rate was enhanced more than the fluorescence decay rate increased. The radiative decay rate of the OH-substituted Ge(IV) porphyrin is even greater due to more intensive π-conjugation of the metalloporphyrin in the excited state. The metal incorporation into the core also enhanced the nonradiative decay rates due to increased spin-orbit coupling and, consequently, reduced the fluorescence lifetimes and quantum yields. However, the spin-orbit coupling effect is not as large as expected. On the other hand, the OH group substitution enhanced only the nonradiative decay rate of the Ge(IV) metalloporphyrin and did not increase that of the free base porphyrin. This is ascribed to much more intensive π-conjugation of the Ge(IV) metalloporphyrin in the excited state which may induce excited state charge transfer and structural distortion.

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