Spectroscopic, photophysical, and redox properties of some meso-substituted free-base porphyrins

Fonda, Harold N.; Gilbert, Julanna V.; Cormier, Russell A.; Sprague, Julian; Kamioka, Keiko; Connolly, John S.

doi:10.1021/j100129a017

Cited by 110 publications

(63 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…They attribute this result to orbital symmetry considerations. As we noted, mesityl groups exhibit dihedral angles of ∼90°, whereas tolyl groups sit at an angle closer to 60° (38).…”

Section: Discussionsupporting

confidence: 53%

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Swierk¹,

Méndez-Hernández

McCool³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

140

107

View full text Add to dashboard Cite

Solar fuel generation requires the efficient capture and conversion of visible light. In both natural and artificial systems, molecular sensitizers can be tuned to capture, convert, and transfer visible light energy. We demonstrate that a series of metal-free porphyrins can drive photoelectrochemical water splitting under broadband and red light (λ > 590 nm) illumination in a dye-sensitized TiO2 solar cell. We report the synthesis, spectral, and electrochemical properties of the sensitizers. Despite slow recombination of photoinjected electrons with oxidized porphyrins, photocurrents are low because of low injection yields and slow electron self-exchange between oxidized porphyrins. The free-base porphyrins are stable under conditions of water photoelectrolysis and in some cases photovoltages in excess of 1 V are observed.

show abstract

“…They attribute this result to orbital symmetry considerations. As we noted, mesityl groups exhibit dihedral angles of ∼90°, whereas tolyl groups sit at an angle closer to 60° (38).…”

Section: Discussionsupporting

confidence: 53%

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Swierk¹,

Méndez-Hernández

McCool³

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

140

107

View full text Add to dashboard Cite

show abstract

“…6b), show maxima, respectively, at 645, 588, 548 and 513 nm. Together with the respective S band, these Q bands give a H 2 TPP spectrum with a shape entirely similar to that reported by Fonda et al [15], which was recorded in benzene and shows values of the λ max of the S and Q bands also practically the same as those found in this work.…”

Section: In Situ Spectroelectrochemical Experimentssupporting

confidence: 90%

“…As the E 1/2 3-1 is a good estimate of the energy separation between the HOMO and the LUMO of the reacting molecule [21], we expect that such separation in the H 2 TAPs is smaller than in H 2 TPP and that, therefore, the first Q band of the visible spectra of those porphyrins is shifted to the red relatively to the same band of the H 2 TPP visible spectrum. As shown in Section 3.2, such shift was indeed observed in this work and also in work done by other workers on meso-H 2 TAPs [15]. (e) The considerable cathodic shift (≈200 mV) of the peak potential of the second oxidation process of the H 2 TAPs relatively to the peak potential of the same process for H 2 TPP points to the destabilization of their -cations (1-4) Indicate the redox processes: 1, porphyrin/-anion; 2, -anion/-dianion; 3, porphyrin/-cation; 4, -cation/-dication.…”

Section: Redox Processes: General Datasupporting

confidence: 89%

“…It is then probable that the alkyl porphyrins P1, P2 and P3 studied in this work are structurally deformed. Fonda et al [15] arrived at the same conclusion in their study of meso-substituted porphyrins (tetra-methyl-and tetrapentyl-). (f) The E 1/2 of the different redox processes of the H 2 TAPs are practically the same for the same ES.…”

Section: Redox Processes: General Datamentioning

confidence: 65%

“…Fonda et al studied seven mesosubstituted porphyrins (two of them were the meso-tetramethyl and the meso-tetra-pentyl porphyrins) [15], but their experimental work was mainly directed to the collection of spectroscopic and photophysical data and very few redox potential values were measured.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins

Paliteiro

Sobral

2005

Electrochimica Acta

View full text Add to dashboard Cite

A series of three meso-tetra-alkyl porphyrins (H 2 TAPs) were synthesised and their electrochemical properties were studied in dichloromethane containing either tetra-butyl ammonium perclorate (TBAP) or tetra-butyl ammonium hexafluorophosphate TBA(PF 6 ) as supporting electrolyte (SE) by cyclic voltammetry and in situ UV/vis spectroelectrochemistry. Values of E 1/2 for the recorded four redox processes of these porphyrins and of the meso-tetra-phenyl porphyrin (H 2 TPP) on glassy carbon and platinum were measured and compared. The redox data collected on the first oxidation and the first reduction processes predict that the value of (LUMO − HOMO) for the H 2 TAPs is lower than for meso-tetra-phenyl porphyrin and, therefore, that the first Q band of the electronic spectra of the H 2 TAPs is red shifted relatively to the same band in the spectrum of H 2 TPP; this shift was indeed found. The second oxidation process of the H 2 TAPs is influenced by the supporting electrolyte used and the dication then formed is consumed by an irreversible chemical reaction. The species produced in this reaction is irreversibly reduced at a considerably lower potential. The electrochemical and spectroelectrochemical data collected are consistent with the occurrence of structural distortion in the macrocycle rings of the H 2 TAPs.

show abstract

Luminescence and structure of the protonated forms ofmeso-tetraarylporphyrins in solution

1998

View full text Add to dashboard Cite

Spectroscopic, photophysical, and redox properties of some meso-substituted free-base porphyrins

Cited by 110 publications

References 1 publication

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Metal-free organic sensitizers for use in water-splitting dye-sensitized photoelectrochemical cells

Electrochemical and spectroelectrochemical characterization of meso-tetra-alkyl porphyrins

Luminescence and structure of the protonated forms ofmeso-tetraarylporphyrins in solution

Contact Info

Product

Resources

About