Spectroelectrochemical and photophysical properties of a (3,4-pyridyl) porphyrazine supermolecule containing four [Ru(bipy)2Cl]+ groups

Toyama, Marcos Makoto; Franco, Marcelo; Catalani, Luiz H.; Araki, Koji; Toma, Henrique E.

doi:10.1016/s1010-6030(98)00337-2

Cited by 21 publications

(7 citation statements)

References 21 publications

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“…Photobleaching was irreversible and was characterized by absorbance loss in all Pz bands (300 to 700 nm), accompanied by a small absorbance increase in the 700 to 800 nm region (Figure a). Absorption of Pzs in the NIR have been previously attributed to a macrocycle-based radical species (this will be further discussed below) . Photobleaching quantum yields (Φ pb ) of Pzs were calculated by using the values of the photobleaching rate ( k pb ) taken from the fitting of the absorption decay curves to a kinetic model, which was developed to allow better fittings to the experimental data (see SI Section S1.1).…”

Section: Resultsmentioning

confidence: 99%

Photobleaching Efficiency Parallels the Enhancement of Membrane Damage for Porphyrazine Photosensitizers

et al. 2019

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Photostability is considered a key asset for photosensitizers (PS) used in medical applications as well as for those used in energy conversion devices. In light-mediated medical treatments, which are based on PS-induced harm to diseased tissues, the photoinduced cycle of singlet oxygen generation has always been considered to correlate with PS efficiency. However, recent evidence points to the fundamental role of contact-dependent reactions, which usually cause PS photobleaching. Therefore, it seems reasonable to challenge the paradigm of photostability versus PS efficiency in medical applications. We have prepared a series of Mg(II) porphyrazines (MgPzs) having similar singlet oxygen quantum yields and side groups with different electron-withdrawing strengths that fine-tune their redox properties. A detailed investigation of the photobleaching mechanism of these porphyrazines revealed that it is independent of singlet oxygen, occurring mainly via photoinduced electron abstraction of surrounding electron rich molecules (solvents or lipids), as revealed by the formation of an air-stable radical anion intermediate. When incorporated into phospholipid membranes, photobleaching of MgPzs correlates with the degree of lipid unsaturation, indicating that it is caused by an electron abstraction from the lipid double bond. Interestingly, upon comparing the efficiency of membrane photodamage between two of these MgPzs (with the highest and the lowest photobleaching efficiencies), we found that the higher the rate of PS photobleaching the faster the leakage induced in the membranes. Our results therefore indicate that photobleaching is a necessary step toward inflicting irreversible biological damage. We propose that the design of more efficient PS for medical applications should contemplate contact-dependent reactions as well as strategies for PS regeneration.

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Section: Resultsmentioning

confidence: 99%

Photobleaching Efficiency Parallels the Enhancement of Membrane Damage for Porphyrazine Photosensitizers

et al. 2019

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“…When coupled to Ru(II) polypyridyl complexes, with their stable redox properties and their ability to enhance the photophysical properties of the porphyrin core, a synergistic effect is observed [10][11][12][13][14][15]. Add to this the excited state stabilizing effect from incorporation of fluorinated groups into the porphyrin structure [16] and the result is a longer lived photosensitizer excited state with greater probability of electron or energy transfer.…”

Section: Introductionmentioning

confidence: 99%

Anaerobic photocleavage of supercoiled DNA by a ruthenium(II) substituted fluorinated porphyrin

McCrate

Carlone

Nielsen

et al. 2010

Inorganic Chemistry Communications

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“…The metalloporphyrins/ tetraazaporphyrins and ruthenium(II) polypyridyls are versatile and robust chromophores possessing strong visible region absorption and reversible redox behavior. These compounds have potential applications as photosensitizers [15][16][17][18][19][20][21][22][23][24] for developing molecule based materials and supramolecular organic photonic devices. We have recently synthesized several new metallotetraazaporphyrins and have incorporated them into a PVC matrix as ion carrier agents, in order to fabricate different ion selective electrodes [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, spectroscopic and electrochemical investigations of supramolecular nickel(II)tetraazaporphyrin complexes

Prasad

Kumar

2005

J. Porphyrins Phthalocyanines

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The (bpy) 2 Ru II and (phen) 2 Ru II moieties were linked to [Ni(OBTTAP)] 1, periphery through coordinate bonds in order to synthesize cationic di-and pentanuclear complexes 2-5 that were obtained as PF 6 -salts. They were characterized by IR, 1 H NMR, UV-vis, and mass spectral data. The electronic absorption, emission and redox data of these bichromophoric systems indicate the presence of a high degree of intercomponent electronic interaction. The position and relative intensities of the Soret and Q bands in these complexes is altered due to peripheral binding of the metal units. The compounds were non-emissive for the Q band excitation but, Soret excitation led to a strong S 2 emission, observed between 400-450 nm. In cyclic voltammetry, the compounds exhibited one Ru centered oxidation together with one or two OBTTAP centered oxidations. The Ru II /Ru III oxidations were observed at significantly lower potentials as compared to the corresponding simple maleonitrilebenzylthioether complexes and has been interpretted in terms of weaker dπ(S)−dπ(Ru) interactions.

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Spectroelectrochemical and photophysical properties of a (3,4-pyridyl) porphyrazine supermolecule containing four [Ru(bipy)2Cl]+ groups

Cited by 21 publications

References 21 publications

Photobleaching Efficiency Parallels the Enhancement of Membrane Damage for Porphyrazine Photosensitizers

Photobleaching Efficiency Parallels the Enhancement of Membrane Damage for Porphyrazine Photosensitizers

Anaerobic photocleavage of supercoiled DNA by a ruthenium(II) substituted fluorinated porphyrin

Synthesis, spectroscopic and electrochemical investigations of supramolecular nickel(II)tetraazaporphyrin complexes

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