Photophysics and photochemistry of water-soluble, sitting-atop bis-thallium(I) 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin

Valicsek, Zsolt; Horváth, Ottó; Stevenson, Kenneth L.

doi:10.1039/b405105j

Cited by 35 publications

(59 citation statements)

References 31 publications

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“…As shown in Fig 5, upon increasing the concentration of the metal ion (La 3+ ) 50 at constant porphyrin concentration in the presence of chloride, no isosbestic point can be observed in the series of absorption spectra. This spectral change clearly indicates that the increasing concentration of the monoporphyrin complex is accompanied by the appearance of bis-or, much less probably at these 55 concentrations, oligoporphyrins. Thus, deviating from the corresponding system containing acetate, beside the red shift of the Soret-band (compared to that of the free base), a decrease of the absorbance can be observed -to about half that of the monoporphyrin (which is very similar to the absorbance of the free 60 base).…”

Section: Bisporphyrin Complexmentioning

confidence: 97%

“…2 and 3. The individual absorption spectra obtained through this procedure for the monoporphyrin complex in the presence of acetate and chloride ions (as potentially axial ligands) are compared with that of the free 55 base in Figs. 3 and 4, regarding the Soret-and the Q-bands, respectively.…”

Section: Monoporphyrin Complexesmentioning

confidence: 99%

“…6.410 -4 M) of La 3+ was too low for an efficient hydrolysis, the pH of the solutions was not lower than 6 even in the absence of buffer. Thus, no protonation of H2TSPP 4-could occur, according to the corresponding equilibrium constants 55 (pK3=4.99, pK4=4.76 29 ).…”

Section: Analyticalmentioning

confidence: 99%

“…While the photoinduced behavior of normal metalloporphyrins have been thoroughly studied for several decades, the investigation 55 of OOP complexes started in this respect only in the past 8-10 years, especially in aqueous systems.…”

Section: Introductionmentioning

confidence: 99%

“…Accordingly, the quantum yields for the photoredox degradation of Tl(I)2TSPP 4-were more than one order of magnitude higher than those (under similar conditions) for the reaction of Tl(III)TSPP 3-. 55,52 Moreover, the in-plane metalloporphyrin Fe(III)TSPP 3-does not display any photoredox 50 degradation, while the corresponding Fe(II) complex (of OOP a Φ(S1B) = φ(IC S2S1)×φ(S1) and kr(S1) = φ(S1)/τ(S1);. b from Qy-state.…”

mentioning

confidence: 99%

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Equilibrium, photophysical and photochemical examination of anionic lanthanum(iii) mono- and bisporphyrins: the effects of the out-of-plane structure

2012

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Lanthanum(III) ion forms kinetically labile complexes with the 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin anion (H2TSPP 4-), the compositions and formation constants of which significantly depend on the presence of potential axial ligands (at 0.01 M). Deviating from the chloride ion, acetate coordinating to the metal center hinders the formation of bisporphyrin complex. In these 10 lanthanum(III) complexes, the metal center, due to its large ionic radius (103.2 pm), is located out of the ligand plane, distorting it. Accordingly, the absorption and fluorescence spectra of these coordination compounds display special properties characteristic of the so-called sitting-atop (SAT) or out-of-plane (OOP) porphyrin complexes. Metalation significantly decreases the quantum yield of the fluorescence from the S1 excited state. Quantum chemical calculations (DFT) confirm the considerable OOP 15 displacement of the La(III) center (about 120 pm in the monoporphyrin complexes). The monoporphyrins display efficient fluorescence (0.03), while the bisporphyrin does not emit. Differing from the normal (in-plane) metalloporphyrins, excitation of these lanthanum(III) porphyrins leads to an irreversible ligandto-metal charge transfer (LMCT) followed by the opening of the porphyrin ring, which is also typical of OOP complexes. Dissociation releasing free-base porphyrin can also be observed upon irradiation of the 20 monoporphyrin in acetate solution, while in the presence of chloride ions interconversions of the monoand bisporphyrins may also take place beside the irreversible photoredox reaction.

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Section: Bisporphyrin Complexmentioning

confidence: 97%

Section: Monoporphyrin Complexesmentioning

confidence: 99%

Section: Analyticalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Equilibrium, photophysical and photochemical examination of anionic lanthanum(iii) mono- and bisporphyrins: the effects of the out-of-plane structure

2012

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Sunlight‐Driven Formation and Dissociation of a Dynamic Mixed‐Valence Thallium(III)/Thallium(I) Porphyrin Complex

et al. 2015

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Inspired by a Newtons cradle device and interested in the development of redox-controllable bimetallic molecular switches, a mixed-valence thallium(III)/thallium(I) bis-strap porphyrin complex, with Tl III bound out of the plane of the N core and Tl I hung to a strap on the opposite side, was formed by the addition of TlOAc to the free base and exposure to indirect sunlight. In this process, oxygen photosensitization by the porphyrin allows the oxidation of Tl I to Tl III . The bimetallic complex is dynamic as the metals exchange their positions symmetrically to the porphyrin plane with Tl III funneling through the macrocycle. Further exposure of the complex to direct sunlight leads to thallium dissociation and to total recovery of the free base. Hence, the porphyrin plays a key role at all stages of the cycle of the complex: It hosts two metal ions, and by absorbing light, it allows the formation and dissociation of Tl III . These results constitute the basis for the further design of innovative light-driven bimetallic molecular devices.[*] V.

show abstract

Sunlight‐Driven Formation and Dissociation of a Dynamic Mixed‐Valence Thallium(III)/Thallium(I) Porphyrin Complex

et al. 2015

View full text Add to dashboard Cite

Inspired by a Newton's cradle device and interested in the development of redox-controllable bimetallic molecular switches, a mixed-valence thallium(III)/thallium(I) bis-strap porphyrin complex, with Tl(III) bound out of the plane of the N core and Tl(I) hung to a strap on the opposite side, was formed by the addition of TlOAc to the free base and exposure to indirect sunlight. In this process, oxygen photosensitization by the porphyrin allows the oxidation of Tl(I) to Tl(III). The bimetallic complex is dynamic as the metals exchange their positions symmetrically to the porphyrin plane with Tl(III) funneling through the macrocycle. Further exposure of the complex to direct sunlight leads to thallium dissociation and to total recovery of the free base. Hence, the porphyrin plays a key role at all stages of the cycle of the complex: It hosts two metal ions, and by absorbing light, it allows the formation and dissociation of Tl(III). These results constitute the basis for the further design of innovative light-driven bimetallic molecular devices.

show abstract

Photophysics and photochemistry of water-soluble, sitting-atop bis-thallium(I) 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin

Cited by 35 publications

References 31 publications

Equilibrium, photophysical and photochemical examination of anionic lanthanum(iii) mono- and bisporphyrins: the effects of the out-of-plane structure

Equilibrium, photophysical and photochemical examination of anionic lanthanum(iii) mono- and bisporphyrins: the effects of the out-of-plane structure

Sunlight‐Driven Formation and Dissociation of a Dynamic Mixed‐Valence Thallium(III)/Thallium(I) Porphyrin Complex

Sunlight‐Driven Formation and Dissociation of a Dynamic Mixed‐Valence Thallium(III)/Thallium(I) Porphyrin Complex

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