NH tautomerism and visible absorption spectra of porphyrins with asymmetrical substitution: Oscillator model and MO calculations

Zenkevich, É. I.; Шульга, А. М.; Filatov, I. V.; Chernook, A. V.; Gurinovich, G. P.

doi:10.1016/0009-2614(85)87014-7

Cited by 24 publications

(18 citation statements)

References 9 publications

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“…The tautomerism is related to the position of the two inner hydrogen atoms (NH tautomers). 64 In the case of Ce6, six independent conformations can be realized, hence one should in principle consider six different isomers.…”

Section: Tautomeric Equilibrium and Force Eld Performancementioning

confidence: 99%

Photophysics of chlorin e6: from one- and two-photon absorption to fluorescence and phosphorescence

2017

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Section: Tautomeric Equilibrium and Force Eld Performancementioning

confidence: 99%

Photophysics of chlorin e6: from one- and two-photon absorption to fluorescence and phosphorescence

2017

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“…We also observe that the maximum decrease of the peak absorption of form 2, ∆α (1) is about 20 times smaller than the corresponding increase of the absorption of form 2, ∆α (2) . This fact is due to change of the oscillator strength of that particular Q-transition as has been discussed earlier in [12,13]. Figure 3b shows also that the lowest Q-band maxima of form 1 and form 2 are distinctly different, with practically no overlap.…”

Section: Two-photon Absorption Induced Photo-tautomerizationmentioning

confidence: 73%

New two-photon materials for fast volumetric rewritable optical storage

et al. 2004

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We study reversible photo-tautomerization induced by simultaneous two-photon absorption (2PA) in tetrapyrrolic molecules as a potential re-writable mechanism for fast, high-density volumetric optical memory. We show that by illuminating Br-tetra-ethyl-porphyrin (Br-TEP) with 150-fs pulses in the near-IR wavelength range the molecule can be switched between two tautomer forms with distinct spectral absorption-and fluorescence signatures in a fully reversible manner. The 2PA cross section in the illumination wavelength range 775-810 nm is measured and the figure of merit, F= φxσ 2 ~ 5x10 -53 cm 4 photon -1 s -1 is estimated for one of the tautomer forms of Br-TEP. Enhanced selectivity of 2PA-induced switching in the near-IR, with respect to one-photon excitation at the same transition energy is observed. We propose to overcome the limitation imposed by the small value of the 2PA cross section by introducing a new class of tetrapyrrolic molecules with greatly enhanced two-photon absorption efficiency. In this paper we present for the first time the structure and absorption properties of asymmetrical chlorin molecules with an attached 2PA-enhancing side group. Potential use of these new materials for high-density re-writable two-photon volumetric optical storage is discussed.

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“…NH-tautomerism of symmetrical porphyrins can be studied at very low temperatures in Shpol'ski or rare gas matrices under spectrally selective laser excitation only. 19,20 In the case of porphyrins with nonsymmetrical substitutions, it has been shown, 21,22 that the spectral separation between absorption bands of lowest energy for two NH-tautomers has a value of about 300 cm -1 . At the same time, the fluorescence spectrum of each tautomer were possible to resolve only at 77 K. Moreover, there is a gap in knowledge about the influence of NH-tautomerism of nonsymmetrical porphyrins on probabilities of radiative and nonradiative deactivation pathways of the excited states.…”

Section: Introductionmentioning

confidence: 98%

Novel cycloketo tetraphenylporphyrins: spectroscopic study of structure-properties relationships

Ermilov

Jasinski

Jux

et al. 2008

Linear and Nonlinear Optics of Organic Materials VIII

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The developments in porphyrin chemistry over the last decades give great advantages for the practical use of porphyrin-based compounds. The properties of these compounds can be systematically tuned by rational utilization of substituents on meso-and/or β-positions as well as by using different metal atoms in the center of the tetrapyrrole macrocycle.Recently we prepared novel mono-and bis-functionalized cycloketo-porphyrins (CKPors). In this work the results of detailed spectroscopic investigations of these compounds are presented. It was found that a seven-membered ketone exocycle remarkably influences the photophysical properties of the CKPor systems. For mono-functionalized CKPors it results in strongly enhanced probability of intersystem crossing S 1 → T 1 with an ISC quantum yield up to 90 %. Moreover, the absorption of all CKPors undergoes a bathochromic shift and the Q-bands extinction is above two times higher compared to that of H 2 TPP, what makes these compounds promising candidates for use as photosensitizers in photodynamic therapy of tumors.For the first time two NH-tautomers of nonsymmetrical CKPors were experimentally resolved at room temperature using optical spectroscopic methods. It was found that the concentration of tautomer A with a lower frequency of the S 0,0 → S 1,0 transition is higher than that one of tautomer B at room temperature, and becomes dominant with cooling down. In contrast -and as it is expected -only one optical active species was observed for nonsymmetrical CKPor with a central Zn(II) atom as well as for symmetrical bis-CKPor.

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NH tautomerism and visible absorption spectra of porphyrins with asymmetrical substitution: Oscillator model and MO calculations

Cited by 24 publications

References 9 publications

Photophysics of chlorin e6: from one- and two-photon absorption to fluorescence and phosphorescence

Photophysics of chlorin e6: from one- and two-photon absorption to fluorescence and phosphorescence

New two-photon materials for fast volumetric rewritable optical storage

Novel cycloketo tetraphenylporphyrins: spectroscopic study of structure-properties relationships

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