Electronic effects in transition-metal porphyrins. 4. Effect of unsymmetrical phenyl substitution on the NMR spectra of a series of metal-free and zinc tetraphenylporphyrins

Walker, F. Ann; Balke, Virginia L.; McDermott, Gregory A.

doi:10.1021/ic00139a017

Cited by 42 publications

(19 citation statements)

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“…It is observed that in the free base porphyrins the internal N-H protons are upfield (Ϫ2.74 to Ϫ2.86 ppm), and β-protons appear at 8.84-8.87 ppm. 9, 10 The meso-phenyl protons consist of a doublet for the ortho-hydrogens (8.08 to 8.24 ppm) and another doublet (7.27 to 7.76 ppm) for the meta-protons. The meta-and para- hydrogens of H 2 TPP overlap and give a doublet (7.75-7.77 ppm).…”

Section: H Nmrmentioning

confidence: 99%

“…The meta-and para- hydrogens of H 2 TPP overlap and give a doublet (7.75-7.77 ppm). 9, 10 Complexation of porphyrins with DDQ, similar to the diprotonation of H 2 TPP, 5b affords a downfield motion of N-H signals (∆δ = 2.34 to 2.62 ppm) and an upfield shift of β-protons (∆δ = Ϫ0.25 to Ϫ0.38 ppm), Table 2. Both of these changes are in the direction to be expected if the ring current of the porphyrin core decreases on complexation.…”

Section: H Nmrmentioning

confidence: 99%

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Exclusive 2∶1 molecular complexation of 2,3-dichloro-5,6-dicyanobenzoquinone and para-substituted meso-tetraphenylporphyrins: spectral analogues for diprotonated meso-tetraphenylporphyrin

Mohajer

Dehghani

2000

J. Chem. Soc., Perkin Trans. 2

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Section: H Nmrmentioning

confidence: 99%

Section: H Nmrmentioning

confidence: 99%

Exclusive 2∶1 molecular complexation of 2,3-dichloro-5,6-dicyanobenzoquinone and para-substituted meso-tetraphenylporphyrins: spectral analogues for diprotonated meso-tetraphenylporphyrin

Mohajer

Dehghani

2000

J. Chem. Soc., Perkin Trans. 2

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“…In the free base porphyrins the internal NH protons are upfield (À2.75 to À2.77 ppm), and b protons appear at 8.85 to 8.86 ppm (Table 1). 2,3 The meso-phenyl protons are composed of a doublet for the ortho-hydrogens (8.08 to 8.24 ppm), and another doublet (7.27 to 7.56 ppm) for the metaprotons. For H 2 tpp the meta-and para-hydrogens overlap and give a doublet (7.75, 7.77 ppm) (Fig.…”

mentioning

confidence: 99%

“…2a). 2,3 Complexation of these porphyrins (por) with A I and A II , analogous to the diprotonation of H 2 tpp 4 and complexation of porphyrins with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) 1c and tetracyanoethylene (TCNE), 1d affords a downfield motion of NH signals (Dd ¼ 3.04 to 3.29 ppm) and an upfield shift of b-protons (Dd ¼ À0.26 to À0.43 ppm) (Table 1). Also, in a similar fashion, all the phenyl ring protons show a downfield shift, ortho-phenyl and b-pyrrole hydrogens overlap and give a broad line at 8.42 to 8.63 ppm.…”

mentioning

confidence: 99%

Novel 1∶2 molecular complexation of free base meso-tetraphenylporphyrins with σ-acceptor trialkylsilyl chlorides

Mohajer

Rayati

2002

New J. Chem.

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Interaction of various molar ratios of meso-tetraphenylporphyrins with two different trialkylsilyl chlorides in chloroform only afforded l:2 molecular complexes at room temperature. Spectral properties closely corresponded to those of diprotonated mesotetraphenylporphyrin, strongly suggesting similar pseudo tetrahedrally distorted porphyrin core structures with s-bonding from two pyrrolenine nitrogen donors to the silicon centers and two hydrogen bonds between two pyrrole NHÁ Á Á and Á Á ÁClSi groups from above and below the mean plane of the porphyrins with nearly trigonal bipyramidal coordination geometries for silicon centers, with alkyl groups located at the equatorial sites.

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“…Those variations in the proton NMR spectra are ascribed to the energy cost on the non-planar distortion geometry depicted by the porphyrin structure during its complexes formation. The difference between these protons in regard to their intensity and signal splitting is related to the geometry instead of molecular symmetry [29] [30].…”

Section: H Nmr Spectramentioning

confidence: 99%

Photophysical, Electrochemical and Photovoltaic Properties of Porphyrin-Based Dye Sensitized Solar Cell

Ghann¹,

Chavez-Gil²,

Goede³

et al. 2017

AMPC

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Porphyrins occur in a number of important biomolecules and are also synthetically made for use as probe component of chemical and biological sensors. The performance of dye sensitized solar cells with two different porphyrin dyes was investigated in this work. The two porphyrin complexes comprised of a metal-free 5, 10, 15, 20-meso-tetrakis-(9H-2-fluorene-yl) porphyrin (H 2 TFP) and its Zinc complex (ZnTFP). UV-Vis, Fluorescence, and Fourier transformed infrared measurements of the two dyes were carried out to evaluate their absorption, emission and binding characteristics. Both dyes absorbed light in the UV-visible region all the way to the near-infrared. The surface morphology and elemental analysis of the porphyrin dye sensitized photoanodes were determined using Field Emission Scanning Electron Microscopy Imaging and Transmission Electron Microscopy Imaging. Cyclic voltammetry studies, current-voltage characteristics and the electrochemical impedance spectroscopic studies were also carried out. Solar-to-electric energy efficiency of H 2 TFP dye sensitized solar cell was higher (0.11%) than that of the zinc complex (0.08%). Thus the metal free porphyrin generated more power than the zinc complex under similar conditions. The impedance measurement also displayed less overall resistance for the free porphyrin (50 Ω) compared with the zinc complex (130 Ω). The LUMO levels of H 2 TFP and ZnTFP sensitizers were −0.87 eV and −0.77 eV respectively. Both of these LUMO values are higher than the lower bound level of the conduction band of TiO 2 (−4.0 eV), ensuring the efficient injection of an electron from the excited porphyrin dye to the conduction band of the titanium dioxide.

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Electronic effects in transition-metal porphyrins. 4. Effect of unsymmetrical phenyl substitution on the NMR spectra of a series of metal-free and zinc tetraphenylporphyrins

Cited by 42 publications

References 1 publication

Exclusive 2∶1 molecular complexation of 2,3-dichloro-5,6-dicyanobenzoquinone and para-substituted meso-tetraphenylporphyrins: spectral analogues for diprotonated meso-tetraphenylporphyrin

Exclusive 2∶1 molecular complexation of 2,3-dichloro-5,6-dicyanobenzoquinone and para-substituted meso-tetraphenylporphyrins: spectral analogues for diprotonated meso-tetraphenylporphyrin

Novel 1∶2 molecular complexation of free base meso-tetraphenylporphyrins with σ-acceptor trialkylsilyl chlorides

Photophysical, Electrochemical and Photovoltaic Properties of Porphyrin-Based Dye Sensitized Solar Cell

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