Transient raman spectroscopic investigations on ruiitpp(L)2 (L = Pyridine and Piperidine) and RuIITPP(CO)(py) in various solvents

alternation of excited charge transfer depending on axial ligation

Sae Chae Jeoung, Dongho Kim, Dae Won Cho, Minjoong Yoon, Kwang Hyun Ahn

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Transient Raman spectra with an excitation of nanosecond pulses at 416 nm were first recorded for RuIITPP(L)2 (L = pyridine and piperidine) and RuIITPP(CO)(py) in various solvents such as benzene, tetrahydrofuran, pyridine, and piperidine. This work is intended to investigate the nature of the charge transfer states accompanied by photoexcitation. It was found that the electronic structure of the lowest energy charge transfer (CT) state is largely dependent on not only the nature of axial ligands attached to the central metal but also the solvents employed. As for RuIITPP(L)2 (L = pyridine and piperidine) in neat pyridine and piperidine solvents, the transient species were observed to be different in structure depending on the axial ligand. Several reasons for this observation were considered, including the discussion on the nature of the CT states such as (π,d), (d,d), (d.π(L)) (L = axial ligand), and (d.π;r*(ring)) states, and the configuration interaction between the two eg(π*) orbitals. The present transient Raman spectroscopic studies on photoexcited RuTPP(pip)2 has manifested the Jahn-Teller effects, which may result in a diamond distortion of the porphyrin ring superimposed by a minor rectangular distortion. This major B2g distortion accounts for the observation of a variety of unusual Raman spectral features in photoexcited RuIITPP(pip)2. Meanwhile, the introduction of a CO ligand to RuII porphyrin also altered the nature of the CT state in nonligating and weakly ligating solvents. It was observed that the CO ligand of the carbonylated RuII porphyrin was substantially replaced by the solvent molecules such as pyridine and piperidine in the excited state. These experimental results were interpreted in terms of the change in the charge distribution among the porphyrin ring, the central metal and the axial ligand in the metal-to-ring (dT,eg(π*)) CT state. The relevance of our findings to the photodynamics observed by the previous picosecond transient absorption measurements of photoexcited Ru(II) porphyrins is discussed in terms of the conformational changes of photoexcited species.

Original languageEnglish
Pages (from-to)8867-8874
Number of pages8
JournalJournal of Physical Chemistry
Volume100
Issue number21
Publication statusPublished - 1996 Dec 1

Fingerprint

piperidine
alternations
Carbon Monoxide
Pyridine
Porphyrins
Charge transfer
pyridines
porphyrins
Ligands
charge transfer
ligands
Metals
rings
metals
Jahn-Teller effect
Diamond
Photoexcitation
Charge distribution
tetrahydrofuran
Benzene

All Science Journal Classification (ASJC) codes

  • Engineering(all)
  • Physical and Theoretical Chemistry

Cite this

@article{c161455fb737496b92a47b6d312d6d95,
title = "Transient raman spectroscopic investigations on ruiitpp(L)2 (L = Pyridine and Piperidine) and RuIITPP(CO)(py) in various solvents: alternation of excited charge transfer depending on axial ligation",
abstract = "Transient Raman spectra with an excitation of nanosecond pulses at 416 nm were first recorded for RuIITPP(L)2 (L = pyridine and piperidine) and RuIITPP(CO)(py) in various solvents such as benzene, tetrahydrofuran, pyridine, and piperidine. This work is intended to investigate the nature of the charge transfer states accompanied by photoexcitation. It was found that the electronic structure of the lowest energy charge transfer (CT) state is largely dependent on not only the nature of axial ligands attached to the central metal but also the solvents employed. As for RuIITPP(L)2 (L = pyridine and piperidine) in neat pyridine and piperidine solvents, the transient species were observed to be different in structure depending on the axial ligand. Several reasons for this observation were considered, including the discussion on the nature of the CT states such as (π,d), (d,d), (d.π(L)) (L = axial ligand), and (d.π;r*(ring)) states, and the configuration interaction between the two eg(π*) orbitals. The present transient Raman spectroscopic studies on photoexcited RuTPP(pip)2 has manifested the Jahn-Teller effects, which may result in a diamond distortion of the porphyrin ring superimposed by a minor rectangular distortion. This major B2g distortion accounts for the observation of a variety of unusual Raman spectral features in photoexcited RuIITPP(pip)2. Meanwhile, the introduction of a CO ligand to RuII porphyrin also altered the nature of the CT state in nonligating and weakly ligating solvents. It was observed that the CO ligand of the carbonylated RuII porphyrin was substantially replaced by the solvent molecules such as pyridine and piperidine in the excited state. These experimental results were interpreted in terms of the change in the charge distribution among the porphyrin ring, the central metal and the axial ligand in the metal-to-ring (dT,eg(π*)) CT state. The relevance of our findings to the photodynamics observed by the previous picosecond transient absorption measurements of photoexcited Ru(II) porphyrins is discussed in terms of the conformational changes of photoexcited species.",
author = "Jeoung, {Sae Chae} and Dongho Kim and Cho, {Dae Won} and Minjoong Yoon and Ahn, {Kwang Hyun}",
year = "1996",
month = "12",
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Transient raman spectroscopic investigations on ruiitpp(L)2 (L = Pyridine and Piperidine) and RuIITPP(CO)(py) in various solvents : alternation of excited charge transfer depending on axial ligation. / Jeoung, Sae Chae; Kim, Dongho; Cho, Dae Won; Yoon, Minjoong; Ahn, Kwang Hyun.

In: Journal of Physical Chemistry, Vol. 100, No. 21, 01.12.1996, p. 8867-8874.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Transient raman spectroscopic investigations on ruiitpp(L)2 (L = Pyridine and Piperidine) and RuIITPP(CO)(py) in various solvents

T2 - alternation of excited charge transfer depending on axial ligation

AU - Jeoung, Sae Chae

AU - Kim, Dongho

AU - Cho, Dae Won

AU - Yoon, Minjoong

AU - Ahn, Kwang Hyun

PY - 1996/12/1

Y1 - 1996/12/1

N2 - Transient Raman spectra with an excitation of nanosecond pulses at 416 nm were first recorded for RuIITPP(L)2 (L = pyridine and piperidine) and RuIITPP(CO)(py) in various solvents such as benzene, tetrahydrofuran, pyridine, and piperidine. This work is intended to investigate the nature of the charge transfer states accompanied by photoexcitation. It was found that the electronic structure of the lowest energy charge transfer (CT) state is largely dependent on not only the nature of axial ligands attached to the central metal but also the solvents employed. As for RuIITPP(L)2 (L = pyridine and piperidine) in neat pyridine and piperidine solvents, the transient species were observed to be different in structure depending on the axial ligand. Several reasons for this observation were considered, including the discussion on the nature of the CT states such as (π,d), (d,d), (d.π(L)) (L = axial ligand), and (d.π;r*(ring)) states, and the configuration interaction between the two eg(π*) orbitals. The present transient Raman spectroscopic studies on photoexcited RuTPP(pip)2 has manifested the Jahn-Teller effects, which may result in a diamond distortion of the porphyrin ring superimposed by a minor rectangular distortion. This major B2g distortion accounts for the observation of a variety of unusual Raman spectral features in photoexcited RuIITPP(pip)2. Meanwhile, the introduction of a CO ligand to RuII porphyrin also altered the nature of the CT state in nonligating and weakly ligating solvents. It was observed that the CO ligand of the carbonylated RuII porphyrin was substantially replaced by the solvent molecules such as pyridine and piperidine in the excited state. These experimental results were interpreted in terms of the change in the charge distribution among the porphyrin ring, the central metal and the axial ligand in the metal-to-ring (dT,eg(π*)) CT state. The relevance of our findings to the photodynamics observed by the previous picosecond transient absorption measurements of photoexcited Ru(II) porphyrins is discussed in terms of the conformational changes of photoexcited species.

AB - Transient Raman spectra with an excitation of nanosecond pulses at 416 nm were first recorded for RuIITPP(L)2 (L = pyridine and piperidine) and RuIITPP(CO)(py) in various solvents such as benzene, tetrahydrofuran, pyridine, and piperidine. This work is intended to investigate the nature of the charge transfer states accompanied by photoexcitation. It was found that the electronic structure of the lowest energy charge transfer (CT) state is largely dependent on not only the nature of axial ligands attached to the central metal but also the solvents employed. As for RuIITPP(L)2 (L = pyridine and piperidine) in neat pyridine and piperidine solvents, the transient species were observed to be different in structure depending on the axial ligand. Several reasons for this observation were considered, including the discussion on the nature of the CT states such as (π,d), (d,d), (d.π(L)) (L = axial ligand), and (d.π;r*(ring)) states, and the configuration interaction between the two eg(π*) orbitals. The present transient Raman spectroscopic studies on photoexcited RuTPP(pip)2 has manifested the Jahn-Teller effects, which may result in a diamond distortion of the porphyrin ring superimposed by a minor rectangular distortion. This major B2g distortion accounts for the observation of a variety of unusual Raman spectral features in photoexcited RuIITPP(pip)2. Meanwhile, the introduction of a CO ligand to RuII porphyrin also altered the nature of the CT state in nonligating and weakly ligating solvents. It was observed that the CO ligand of the carbonylated RuII porphyrin was substantially replaced by the solvent molecules such as pyridine and piperidine in the excited state. These experimental results were interpreted in terms of the change in the charge distribution among the porphyrin ring, the central metal and the axial ligand in the metal-to-ring (dT,eg(π*)) CT state. The relevance of our findings to the photodynamics observed by the previous picosecond transient absorption measurements of photoexcited Ru(II) porphyrins is discussed in terms of the conformational changes of photoexcited species.

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