Optical spectra of Cu porphin and VO porphin in single crystal triphenylene

Bohandy, J.; Kim, Boris F.; Jen, C. K.

doi:10.1016/0022-2852(74)90017-4

Cited by 9 publications

(8 citation statements)

References 15 publications

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“…With a further increase of the probe wavelength up to 800 nm, however, the decay profiles exhibit a slight increase in the decay times. These results are partly consistent with the wavelength dependence of the emission lifetimes reported by Gouterman et al 5a 5 Temporal decay profiles of the emission intensity for OV IV TPP at various probe wavelengths following 532 nm excitation at 77 K. The amplitudes of the fast component at various probe wavelengths are displayed in the inset …”

Section: Resultssupporting

confidence: 88%

“…Figure c shows the CW emission spectra of OV IV TPP in the two different solvents at 77 K. Although the emission spectrum in MCH/benzene exhibits a maximum around 745 nm, which is slightly blue-shifted from the reported value of 758 nm in a PMMA matrix, the emission maximum in MCH/THF is observed at 784 nm. The solvent-dependent shifts in the emission bands are in good accordance with the shifts in the absorption spectra (see Figure ).…”

Section: Resultsmentioning

confidence: 98%

“…Prior to further discussion of the data at 77 K, it is appropriate to review briefly the previous investigations of this complicated system. Gouterman et al already reported that the spectral feature and relative emission quantum yield of the photoluminescence of OV IV TPP in poly(methyl methacrylate) (PMMA) matrix do not change at temperatures between 10 and 80 K. Meanwhile, the photoluminescence studies on paramagnetic metalloporphyrins such as Cu II TPP 5 and ClCr III TPP revealed that the longer is the probe wavelength, the slower become the luminescence lifetimes. These probe wavelength dependences of the lifetimes have been well illustrated by theoretical consideration by Gouterman et al in which the transition from the 2 T(π,π*) to the 2 S 0 (π,π*) lies higher in energy and is faster than that from the 4 T(π,π*) to the 2 S 0 (π,π*).…”

Section: Discussionmentioning

confidence: 99%

“…It has been previously reported , that no fluorescence is detected for oxovanadyl(IV) porphyrins, but phosphorescence is observed from their 2 T/ 4 T(π,π*) electronic manifolds at low temperatures. Particularly, the luminescence from oxovanadyl(IV) etioporphyrin (OV IV Etio), β-substituted porphyrin, was reported to exhibit a main peak at 709 nm with weaker bands at 712, 725, and 755 nm.…”

Section: Introductionmentioning

confidence: 99%

“…Their relative intensities vary with temperature. Gouterman et al , assigned the main peak as the luminescence from the 2 T(π,π*) state and the weaker ones as a superposition of the luminescence from the 4 T(π,π*) state and its vibronic bands. The low-temperature luminescence of OV IV TPP consists of one broad peak centered at 758 nm, which is attributed to the tripquartet ( 4 T(π,π*)) state, and its spectral feature as well as emission quantum yield is independent of temperature in the range 10−80 K .…”

Section: Introductionmentioning

confidence: 99%

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Lowest Excited State of Oxovanadyl(IV) Tetraphenylporphyrin

Jeoung¹,

Kim²,

Hahn

et al. 1998

J. Phys. Chem. A

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The excited-state relaxation dynamics and pathways of oxovanadyl(IV) tetraphenylporphyrin (OV IV TPP) have been investigated by nanosecond time-resolved and steady-state emission, transient absorption, and transient resonance Raman spectroscopies. At room temperature, the emission spectrum shows a single broad featureless band centered near 790 nm in noncoordinating solvents such as toluene and benzene and at 814 nm in tetrahydrofuran (THF), whereas at 77 K the emission bands in the same solvents exhibit blue-shifts to 745 and 784 nm, respectively. Furthermore, the emission decay time in benzene increases from 40 to 60 ns with a decrease in temperature from 323 to 268 K. In contrast, the decay time in THF is ca. 10 ns, which is almost independent of temperature. The energy separation between the tripdoublet state ( 2 T(π,π*)) and the tripquartet one ( 4 T(π,π*)) under the proposed relaxation scheme of photoexcited OV IV TPP has been estimated to be ca. 500 cm -1 in benzene and toluene. The transient absorption spectra at room temperature denote a broad featureless absorption centered at around 480 nm with a ground-state bleaching at 555 nm. All the spectroscopic results including the transient Raman spectra led us to conclude that the electronic nature of the lowest excited state should be the tripquartet state ( 4 T(π,π*)) at ambient temperature. The decay times for both photoinduced absorption and bleaching are similar and also in good accordance with the emission decay times as long as temperature and solvent are the same. The time-resolved emission spectra and wavelength dependent decay kinetics at 77 K reveal that the observed emission spectra apparently originate from three different emitting species. These observations are discussed in terms of postulating a quenching state (Q), which is thermally accessible from the tripdoublet state ( 2 T(π,π*)) of OV IV TPP at room temperature.

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Section: Resultssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 98%