Spectroscopic and photochemical properties of water-soluble metalloporphyrins of distorted structure

Horváth, Ottó; Valicsek, Zsolt; Harrach, Gergely; Lendvay, György; Fodor, Melinda A.

doi:10.1016/j.ccr.2012.02.011

Cited by 48 publications

(69 citation statements)

References 103 publications

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“…Metalloporphyrins play important roles in nature, due to their special spectral, coordination and redox features. Their advantageous photoinduced properties can also be exploited in various photocatalytic procedures [1]. Water-soluble derivatives can be utilized in environmentally benign systems not containing organic solvents.…”

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“…The so-called hyper-porphyrins can be especially interesting in this respect, due to their distorted structure, which may increase the (photo)redox reactivity of these complexes. From water-soluble metalloporphyrins of this type, photoredox reactions of manganese(III) complexes were thoroughly studied [1,3,4], while scarce attention was paid to the corresponding cobalt(III) porphyrins in this respect. …”

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Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Fodor¹,

Horváth²,

Fodor³

et al. 2014

Inorganic Chemistry Communications

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Although kinetically inert cationic Co(III)TMPyP 5+ (H2TMPyP 4+ = 5,10,15,20-tetrakis(methylpyridinium-4-yl)porphyrin) was considered earlier to be very weakly emissive, both the spectrum and the lifetime of its fluorescence could be determined. Besides, this complex proved to be favorable for outer-sphere photoinduced reduction of the metal center in the presence of triethanolamine (TEOA) as electron donor quenching the triplet excited state of this metalloporphyrin. The corresponding cobalt(II) porphyrin formed in this way was also photoactive; it forwarded an electron to a suitable acceptor (e.g., methylviologen) upon irradiation, regenerating the starting complex. Hence, this system may be a candidate for hydrogen generation from water by utilization of visible light. Metalloporphyrins play important roles in nature, due to their special spectral, coordination and redox features. Their advantageous photoinduced properties can also be exploited in various photocatalytic procedures [1]. Water-soluble derivatives can be utilized in environmentally benign systems not containing organic solvents. Kinetically inert in-plain metalloporphyrins, in which the metal center coplanarly fits into the cavity of the ligand, may offer promising possibilities for realization of photocatalytic systems based on outer-sphere electron transfer [2]. The so-called hyper-porphyrins can be especially interesting in this respect, due to their distorted structure, which may increase the (photo)redox reactivity of these complexes. From water-soluble metalloporphyrins of this type, photoredox reactions of manganese(III) complexes were thoroughly studied [1,3,4], while scarce attention was paid to the corresponding cobalt(III) porphyrins in this respect. Keywords: cobalt(III) porphyrinPhotocatalytic oxidation of the sulfide content of a wastewater to sulfate was studied with Co(III)TMPyP 5+ , Mn(III)TMPyP 5+ , and Fe(III)TMPyP 5+ (H2TMPyP 4+ = 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin) [5]. Upon irradiation in the range of the Soretbands, the cobalt(III) complex proved to be the most efficient, but the results have not been interpreted. This metalloporphyrin can also connect to the chain of DNA and oxidatively split it in the presence of suitable electron acceptors [6]. Since cationic manganese(III) porphyrins proved to be efficient photocatalysts in the presence of appropriate electron donors (such as EDTA and TEOA) and methylviologen as electron acceptor [1,3,7], cationic cobalt(III) porphyrins, the other characteristic representatives of water-soluble hyper-porphyrins, are also worth investigating in this respect. Hence, in this work, some photophysical and photochemical properties of Co(III)TMPyP 5+ were studied, also confirming its photocatalytic behavior, which may be utilized in water-splitting by solar radiation.The compounds used for our experiments were of reagent grade. Water purified in a Millipore/Milli-Q system was applied as solvent. Stock solutions of Co(III)TMPyP 5+ were prepared by in situ generation ...

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confidence: 99%

Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Fodor¹,

Horváth²,

Fodor³

et al. 2014

Inorganic Chemistry Communications

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“…However, during the photolysis of early lanthanide(III) porphyrins at the maximum of the Q-bands (~555 nm), a new photoproduct appears, which is stable in dark (Fig. 6) and undetectable in the case of post-transition metal ions' typical OOP complexes [1,2]. The Soretband disappeared as a consequence of the ring-opening reaction; hence, the absorption band at 590 nm may be assigned to a complex between lanthanide(III) and this open-chain, dioxotetrapyrrole derivative (Fig.…”

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“…in optical telecommunication, spectral conversion of solar energy, and biomedical optical imaging [11][12][13][14][15][16]. Furthermore, lanthanide(III) porphyrins may be useful in the photocatalytic cleavage of water because the metal center, reduced due to the photoinduced charge transfer from ligand to metal (LMCT) [1,2,17,18], has a negative redox potential large enough to produce hydrogen (except Eu 3+ , Fig. 2) [9].…”

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“…Metal ions can form in-plane metalloporphyrins, fitting into the cavity of the porphyrin ring, or several of them are located out of the ligand plane, resulting in out-of-plane (OOP or sitting-atop=SAT) complexes with dome-distorted structure, thermodynamic instability, kinetic lability, typical photophysical features, and photochemical reactivity [1,2]. Besides, the OOP position promotes the formation of bis-or oligoporphyrins, so called sandwich complexes, mainly if the metal center is susceptible to higher coordination numbers ( Fig.…”

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Peculiar photoinduced properties of water-soluble, early lanthanide(III) porphyrins

Imran

Szentgyörgyi

Eller

et al. 2015

Inorganic Chemistry Communications

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Water-soluble, early lanthanide(III) mono-and bisporphyrin complexes possess very similar UV-Vis absorption, photophysical and photochemical properties, as a consequence of a special type of aggregation, through the peripheral substituents. In the absence of the bidentate, O-donor acetate ligand, bisporphyrin can form too, which has slightly redshifted and broadened absorption bands, compared to those of the monoporphyrin. Also the bisporphyrin displays a blueshifted and less intense fluorescence, related to the free-base porphyrin. The formation of complexes and the transformation between the mono-and bisporphyrins are very slow reactions in dark at room temperature. These reactions are accelerated by the photolysis of the system; which are considerable by-processes of the photoredox degradation. Depending on the wavelength of irradiation, two types of photoproducts can appear: during the photolysis at the Soret-band, a radical type intermediate can be observed, which disappears in dark. However, during the irradiation at the Q-bands, a new photoproduct appears, which is stable in dark and undetectable in the case of post-transition metal ions' out-of-plane porphyrin complexes.

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Porphyrins as Multifunctional Interconnects in Networks of ZnO Nanoparticles and their Application in Dye‐Sensitized Solar Cells

et al. 2017

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ZnO nanoparticles of 2.6 to 4.0 nm in size were interconnected by meso‐tetra(4‐carboxyphenyl)porphyrin (TCPP) for the realization of novel ZnO–TCPP networks, reaching lateral dimensions ranging from 50 to 800 nm. The resulting ZnO–TCPP networks were probed by dynamic light‐scattering experiments, transmission electron microscopy, and spectroscopy, and were also tested as photoactive top layers in TiO2 and ZnO dye‐sensitized solar cells (DSSCs). Control over these ZnO–TCPP networks on top of the semiconductor electrodes enables efficiency increases of 10 % and 46 % for TiO2‐ and ZnO‐based photoelectrodes, respectively. In other words, effects, such as reducing the electron recombination and increasing the electron lifetime, document the benefits of using tailored functional hybrid systems in DSSCs.

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Spectroscopic and photochemical properties of water-soluble metalloporphyrins of distorted structure

Cited by 48 publications

References 103 publications

Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Peculiar photoinduced properties of water-soluble, early lanthanide(III) porphyrins

Porphyrins as Multifunctional Interconnects in Networks of ZnO Nanoparticles and their Application in Dye‐Sensitized Solar Cells

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