67820-10-4

Upstream product

• 616-47-7 1-methyl-1H-imidazole 
• 14074-80-7 zinc tetraphenylporphyrin 

Relevant academic research and scientific papers

Fluorinated aluminum(III) porphyrins: Synthesis, spectroscopy, electrochemistry and photochemistry

A series of fluorinated free-base porphyrins (H2TPPFn, n = 0, 8, 12, 20, 24) and the corresponding aluminum(III) porphyrin (AlTPPFn-Ph, n = 0, 8, 12, 20, 24) derivatives have been synthesized and their spectroscopic, redox and optical properties were investigated. The absorption studies show that the spectral shapes of investigated porphyrins are sensitive to the degree of fluorination on the meso-phenyl units. Analogously, the fluorescence quantum yields and singlet-state lifetimes depend on the number of fluorine atoms, and decrease by increasing the number of fluorine atoms. The H2TPPFn and AlTPPFn-Ph (n = 8, 12, 20, 24) derivatives exhibited lower fluorescence intensities compared to the H2TPP and AlTPP, respectively. However, the AlTPPFn-Ph (n = 0, 8, 12, 20, 24) derivatives yield relatively a strong fluorescence compared to the well-known ZnTPP. As predicted, the redox potentials are shifted to the more positive side by increasing the fluorine atoms. The Lewis acidity of AlTPPFn-Ph was quantified by using the absorption and fluorescence titrations with the Lewis base N-methylimidazole (Me-Im). The titration data suggests that the Lewis acidity of the Al center rises when increasing the number of fluorine atoms on the porphyrin. Together, the high fluorescence quantum yields, high-potentials, unique optical and redox properties suggest that the investigated porphyrins could be potential sensitizers to mimic various components of artificial photosynthetic systems for the production of solar fuels.

Molecular tools for the self-assembly of bisporphyrin photodyads: A comprehensive physicochemical and photophysical study

Accessible and hindered phenanthroline-strapped Zn(II) porphyrin receptors exhibited suitable topography tailored to strongly and selectively bind N 1-unsubstituted imidazoles and imidazoles appended to free-base porphyrins. Distal binding was

Recognition of imidazoles by strapped zinc(II) porphyrin receptors: Insight into the induced-fit mechanism

Imidazole-porphyrin coordination has become an important tool in the design of self-assembled materials. A combination of spectrophotometric and stopped-flow techniques has been used to gain insight into the control of imidazole binding in the distal pocket of phenanthroline-strapped porphyrins. The binding studies of a variety of imidazole substrates in combination with both hindered and accessible receptors have permitted the determination of the thermodynamic and kinetic parameters associated with the imidazole binding.

Extraplanar ligand-exchange dynamics in (tetraphenylporphinato)zinc(II) and the conformation of zinc(II) porphyrins in solution

The extraplanar ligand-exchange dynamics of (tetraphenylporphinato)zinc(II) with pyridine and N-methylimidazole have been studied at 21°C in CDCl3. For the ZnTPP-py system we find kon = 4.90 × 108 M-1 s-1, koff = 1.98 × 105 s-1, and K = 2300 ± 400 M-1. For the ZnTPP-N-MeIm system we find kon = 1.67 × 108 M-1 s-1, koff = 4.78 × 104 s-1, and K = 10 200 ± 600 M-1. An analysis of the steric limitations of ZnTPP and the ligands (pyridine and N-methylimidazole) suggests that kon is close to, if not at, the diffusion-controlled rate limit. Since the ZnTPP-L complexes are known to have the Zn(II) displaced some 0.3 A? out of the mean plane of the porphyrin ring, a diffusion-controlled kon requires that the unligated ZnTPP also be nonplanar.

Reactions of metalloporphyrin π radicals. 1. Complexation of zinc tetraphenylporphyrin cation and anion radicals with nitrogenous bases

Stability constants for TPPZn with 20 nitrogenous bases were obtained by the method of proportional absorbances. These results were combined with electrochemical data to obtain stability constants for the reaction of TPPZn radical cations and radical anions with ligands. Values of log β1 ranged from 1.64 to 4.59 for ligand addition to [TPPZn]+ and from 1.47 to 3.50 for addition to [TPPZn]-. Only five-coordinate complexes were observed. These measurements represented the first values of stability constants obtained for nitrogeneous base addition to porphyrin π radicals. The changes in stability constants observed as a function of ligand pKa allowed the tuning of the zinc radical cation half-wave potential between 0.83 and 0.74 (vs. SCE) and the radical anion potential between -1.38 and -1.49 V. The ligand additions proceeded in a chemically reversible fashion over the experimental time frame. Thin-layer spectra for oxidations showed slight spectral differences between [TPPZn]+ and [TPPZn(L)]+ but were almost totally insensitive to a specific L. The possibility of an alternate oxidative pathway to the β-substituted pyrrole product was examined and found not to be operative for this time frame and solvent system.