Photophysics of water-soluble Cu(II)-porphyrin: groove-bounding to polynucleotide as compared to dissolving in neat buffer solution

Vladimir A. Galievsky; Vladimir S. Chirvony; Laurent Chinsky; Pierre-Yves Turpin

doi:10.1117/12.197449

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2 January 1995 Photophysics of water-soluble Cu(II)-porphyrin: groove-bounding to polynucleotide as compared to dissolving in neat buffer solution

Vladimir A. Galievsky, Vladimir S. Chirvony, Laurent Chinsky, Pierre-Yves Turpin

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Proceedings Volume 2370, 5th International Conference on Laser Applications in Life Sciences; (1995) https://doi.org/10.1117/12.197449
Event: Laser Applications in Life Sciences: 5th International Conference, 1994, Minsk, Belarus

Abstract

Excited-state dynamics of water-soluble Cu-5,10,15,20-tetrakis[4-(N- methylpyridyl)]porphyrin(Cu(TMpy-P4)) groove-bounded to poly(dA-dT) or dissolved in neat water phosphate buffer were investigated. In the first case, double-exponential decay kinetics were found with time constants of 35 +/- 7 ps and 3.2 +/- 0.5 ns. Spectral features of the transient absorption, a comparison with photophysical properties of CuP in oxygen-containing solvents as well as earlier RR investigations of an exciplex formation between Cu(TMpy-P4) and some polynucleotides enable us to attribute the two observed transient species to the triplet ^2,4T₁ state of four-coordinate Cu(TMpy-P4) and to the (d,d) state of five-coordinate Cu(TMpy-P4) axial liganded by CO group of thymine residue, respectively. In the case of Cu(TMpy-P4) in neat phosphate buffer, double-exponential kinetics of a transient species depopulation was observed with time constants of 21 +/- 3 ps and > 2 ns. Spectral feature of the transient absorption enables us to attribute the first transient species to the triplet ^2,4T₁ state. We believe, the reason of such short ^2,4T₁ state lifetime is liganding of the excited Cu(TMpy-P4) by molecules of H₂O resulting in deactivation via downshifted CT state and/or (d,d) state. The second transient species corresponds, most likely, to the (d,d) state.

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Vladimir A. Galievsky, Vladimir S. Chirvony, Laurent Chinsky, and Pierre-Yves Turpin "Photophysics of water-soluble Cu(II)-porphyrin: groove-bounding to polynucleotide as compared to dissolving in neat buffer solution", Proc. SPIE 2370, 5th International Conference on Laser Applications in Life Sciences, (2 January 1995); https://doi.org/10.1117/12.197449

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