Can I read Protonation and Deprotonation of Nitrogens in Tetrapyrazino-porphyrazine Macrocycles on EtoBox?

Protonation and Deprotonation of Nitrogens in Tetrapyrazino-porphyrazine Macrocycles by Pavel Petrik; Petr Zimcik; Kamil Kopecky; Zbynek Musil; Miroslav Miletin; Veronika Loukotova is a Materials Science article available to read on EtoBox.

What is Protonation and Deprotonation of Nitrogens in Tetrapyrazino-porphyrazine Macrocycles about?

Acid-base properties of zinc phthalocyanine (Pc) and zinc and metal-free tetrapyrazinoporphyrazine (TPPz) macrocycles with eight peripheral tert-butylsulfanyl or diethylamino substituents are investigated in this work by means of UV-vis spectroscopy. The Pc and TPPz are protonated on the azomethine nitrogens in acidic media. The monoprotonated form was found using trifluoroacetic acid and lower amounts of H ~2~ SO ~4~. The higher concentrations of sulfuric acid lead to the appearance of the diprotonated form, and possibly also the triprotonated form in the case of Pc. It was found that the pyrazine nitrogens in the TPPz macrocycle undergo protonation at approx. 20-30% of sulfuric acid in THF solution. TPPz with diethylamino peripheral substituents are protonated preferably on these peripheral tertiary amines. Metal-free TPPz can readily lose the hydrogens on central nitrogens in strong basic media (e.g. tetrabutylammonium hydroxide) to directly form a dianion, with no presence of important or detectable amounts of the monoanion species. A different form of deprotonated macrocycle was observed in pyridine suggesting the formation of only a proton transfer complex, not a true ionic f

Who reads Protonation and Deprotonation of Nitrogens in Tetrapyrazino-porphyrazine Macrocycles?

Author

Pavel Petrik; Petr Zimcik; Kamil Kopecky; Zbynek Musil; Miroslav Miletin; Veronika Loukotova

Publisher

World Scientific Pub Co Pte Lt

Published

2007

Language

EN

Field

Materials Science (Physical Sciences)