Search results for "free-base porphyrins"
showing 2 items of 2 documents
meso-Aryl-substituted free-base porphyrins: formation, structure and photostability of diprotonated species
2015
Susceptibility to interact with trifluoroacetic acid (TFA) of selected free-base porphyrins, including a novel lipophilic 3-n-pentadecyl(phenoxy)-ethoxy-phenyl-substituted porphyrin, and photostability of their diprotonated compounds was explored in benzene and N,N-dimethylformamide (DMF). Results have been discussed in terms of the commonly applied pK a -based procedure and confronted with a simple approach derived from experimentally-determined correlations reflecting the porphyrins affinity for TFA. Density functional theory (DFT) has proved the porphyrin moiety creates stable diprotonated species involving two TFA molecules, in which the fluorine atoms effectively contribute to the over…
Tuning the Electrochemistry of Free-Base Porphyrins in Acidic Nonaqueous Media: Influence of Solvent, Supporting Electrolyte, and Ring Substituents
2016
International audience; A detailed study of reduction potentials, electroreduction mechanisms and acid-base chemistry was carried out on two series of free-base porphyrins in nonaqueous media. The first series is represented by four-pyrrole substituted tetraphenylporphyrin (TPP) derivatives, two of which are planar and two of which are nonplanar in their non-protonated form. The second comprises porphyrins with 0-4 meso-phenyl groups on the macrocycle. Equilibrium constants for conversion of each neutral porphyrin to its diprotic [H4P] 2+ form were determined and the electrochemistry was then elucidated as a function of: (i) type of nonaqueous solvent, (ii) anion of supporting electrolyte, …