Photophysical and redox properties of water-soluble porphyrins in aqueous media

Kalyanasundaram, K.; Neumann‐Spallart, M.

doi:10.1021/j100223a022

Cited by 432 publications

(470 citation statements)

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“…However, deviating from the general tendency, in the case of the in-plane porphyrin complexes of Mn(III) and Co(III), this band is red-shifted [16]. This phenomenon is well demonstrated by the Soret-bands of H2TMPyP 4+ and Co(III)TMPyP 5+ at 421 and 434 nm, respectively [17]. Such metalloporphyrins, the spectra of which cannot be interpreted by the 4 MO theory of Gouterman, are classified as hyper-porphyrins [18].…”

mentioning

confidence: 68%

“…Generally, the highly distorted porphyrin complexes with diamagnetic metal center do not display appreciable fluorescence at room temperature [18]. Accordingly, earlier, Mn(III) and Co(III) porphyrins were not found to be fluorescent at all [17]. However, due to our rather sensitive equipment, the emission of this cobalt(III) porphyrin could be measured with an appropriate resolution.…”

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confidence: 97%

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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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mentioning

confidence: 68%

mentioning

confidence: 97%

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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“…The quantum yield of this emission is 2.5 %. 42 The steady state absorption spectrum of CdTe QDs in water shows a 45 band at 510 nm, which is assigned to the first excitonic transition (1s e -1s h ). Using this information the diameter of the QDs was determined spectroscopically to be 2.3  0.2 nm.…”

Section: Zntmpyp4/cdte Qd Assembliesmentioning

confidence: 99%

“…63 Our zinc porphyrin may be both readily oxidised or reduced {E o (P + /P) = 1.18 V and E o (P/P -) = -0.85V}. 42 The redox properties of CdTe have been shown to be size-dependent and 80 influenced by the nature of the capping ligand. 64 Using the measured oxidation potential for CdTe in the range from 2.95 nm to 4.08 nm, 64, 65 we have estimated an oxidation potential of approximately +0.95 V, and a reduction potential of approximately -1.00 V for our 2.3 nm species.…”

Section: Picosecond Transient Absorptionmentioning

confidence: 99%

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

et al. 2012

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The photophysical properties of 2.3 nm thioglycolic acid (TGA) coated CdTe quantum dots (QDs) prepared by a reflux method have been studied in the presence of a cationic meso-tetrakis(4-N-methylpyridyl) zinc porphyrin (ZnTMPyP4). Addition of the CdTe QDs to porphyrin in H 2 O results in a marked red-shift and hypochromism in the porphyrin absorption spectrum, indicative of a non-covalent binding interaction with the QD surface. Low equivalents of the quantum dot were required for complete quenching of the porphyrin fluorescence revealing that one quantum dot 10 may quench more than one porphyrin. Similarly addition of porphyrin to the quantum dot provided evidence for very efficient quenching of the CdTe photoluminescence, suggesting the formation of CdTe-porphyrin aggregates. Definitive evidence for such aggregates was gathered using small angle X-ray spectroscopy (SAXS). Ultrafast transient absorption data are consistent with very rapid photoinduced electron transfer (1.3 ps) and the resultant formation of a long-lived porphyrin species.

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“…In the solid state infrared spectrum, an intense  OCO absorption was observed at 1519 cm -1 . Further functionality was introduced into the system through the reaction of [(Pd-TPP) 30 The increased intensity of the absorptions at 420 nm was attributed to features associated with the ruthenium units.…”

Section: Bi-and Trimetallic Complexesmentioning

confidence: 99%

Multimetallic Complexes and Functionalized Nanoparticles Based on Oxygen- and Nitrogen-Donor Combinations

et al. 2013

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Photophysical and redox properties of water-soluble porphyrins in aqueous media

Cited by 432 publications

References 1 publication

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

Photophysical studies of CdTe quantum dots in the presence of a zinc cationic porphyrin

Multimetallic Complexes and Functionalized Nanoparticles Based on Oxygen- and Nitrogen-Donor Combinations

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