Tetra-2,3-pyrazinoporphyrazines with Externally Appended Pyridine Rings. 3. A New Highly Electron-Deficient Octacationic Macrocycle:  Tetrakis-2,3-[5,6-di{2-(N-methyl)pyridiniumyl}pyrazino]porphyrazine, [(2-Mepy)₈TPyzPzH₂]⁸⁺

Abstract

A new octacationic macrocycle, tetrakis-2,3-[5,6-di{2-(N-methyl)pyridiniumyl}pyrazino]porphyrazine, was obtained in its hydrated form as the water-soluble iodide salt. This compound, abbreviated as [(2-Mepy)(8)TPyzPzH(2)](I(8)).8H(2)O (2-Mepy = 2(N-methyl)pyridiniumyl moiety), was obtained by demetalation of the corresponding Mg(II) complex, [(2-Mepy)(8)TPyzPzMg(H(2)O)](I(8)).5H(2)O, which in turn was prepared from its corresponding neutral hydrated species tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazinato(monoaquo)magnesium(II), [Py(8)TPyzPzMg(H(2)O)].4H(2)O, by reaction with CH(3)I in N,N-dimethylformamide. The quaternization reactions by using CH(3)I or methyl p-toluenesulfonate were also conducted on the monomeric precursor 2,3-dicyano-5,6-di(2-pyridyl)-1,4-pyrazine, [(CN)(2)Py(2)Pyz], with formation of the monoquaternized ion [(CN)(2)Py(2-Mepy)Pyz](+) neutralized by iodide and p-toluenesulfonate anions. Single-crystal X-ray work allowed elucidation of the structure of the two salt-like species. The diquaternized ion [(CN)(2)(2-Mepy)(2)Pyz](2+) could also be obtained as a p-toluenesulfonate salt, but attempts at direct macrocyclization of this dicationic species were unsuccessful. The iodide salt [(2-Mepy)(8)TPyzPzH(2)](I(8)).8H(2)O is water-soluble, with different solubilities depending on the range of pH explored. It was established that the macrocycle [(2-Mepy)(8)TPyzPzH(2)](8+) undergoes facile deprotonation and behaves as a strong acid. Aggregation phenomena are observed for both the octacation [(2-Mepy)(8)TPyzPzH(2)](8+) and its corresponding centrally deprotonated species [(2-Mepy)(8)TPyzPz](6+). Nevertheless, both cationic moieties exist in their monomeric form under specific experimental conditions. UV-visible monitored titrations with NaOH provide information about the type of protonation/deprotonation equilibria which are complicated by the occurrence of aggregation phenomena.

Tetrapyrazinoporphyrazines with different number of peripheral pyridyl rings: Synthesis, photophysical and photochemical properties

“…Tetrapyrazinoporphyrazines (TPyzPA) with eight pyridyl moieties have been investigated for their remarkable electron-deficient properties in electrochemistry both free and quarternized which allowed water solubility [9][10][11][12]. The same compounds have also been investigated for their non-linear optical properties [13].…”

Synthesis and EPR studies of vanadyl tetrakis(selenodiazole)porphyrazine

“…The annulated 1,2,5-selenodiazole rings in the porphyrazine macrocycle, which can easily undergo different transformations [10][11][12][13][14][15][16][17], open up a new synthetic approach to octaaminoporphyrazines. The metalation of free-base porphyrazine cores with metals such as Co(II), Ni(II), Zn(II), etc.…”

Tetrapyrazinoporphyrazines and their metal derivatives. Part I: Synthesis and basic structural information

“…Mono-, bi-and pentametallic complexes of octa(2-pyridyl) substituted TPyzPzs As schematically illustrated in Scheme 31, different series of octa(2-pyridyl) substituted macrocycles can be prepared from [TPyz42PzH 2 ] (A) [119] and its N-methylated octacationic derivative [Me 8 TPyz42PzH 2 ] 8+ (neutralized by I -ions) [205], i.e. mononuclear complexes [TPyz42PzM] (B) [204,207,209,210], the related quaternized octacations [Me 8 TPyz42PzM] 8+ (C) [206,207,209,210], the homo/hetero pentanuclear derivatives [(M'Cl 2 ) 4 TPyz42PzM] (D) [58,207,209,210], the neutral heterobinuclear [(M'Cl 2 )TPyz42PzM] (E) [56] and the externally monoplatinated quaternized hexacations, [(PtCl 2 )Me 6 TPyz42PzM] 6+ [56].…”