Yulia B. Ivanova, Svetlana G. Pukhovskaya, Alexey V. Lyubimtsev, Anna O. Plotnikova, Sergei A. Syrbu
{"title":"Spectral studies of protonated and anionic forms of porphyrins with an asymmetric substitution system","authors":"Yulia B. Ivanova, Svetlana G. Pukhovskaya, Alexey V. Lyubimtsev, Anna O. Plotnikova, Sergei A. Syrbu","doi":"10.1007/s10847-022-01131-8","DOIUrl":null,"url":null,"abstract":"<div><p>The directed synthesis of asymmetrically substituted porphyrins—tetraphenylporphyrine derivatives containing amino acid residues as a functional group, which can be used as “anchor” groups, for incorporation into the structure of a protein molecule, was carried out. The obtained compounds were characterized by a number of spectral methods confirming their structure and purity. Their base and acid ionization constants in the AN–HClO<sub>4</sub> and DMSO–potassium cryptate (KOH[222])—systems were measured by spectrophotometric titration. It was found that the asymmetric substitution architecture contributed to the stabilization of the protonated forms of porphyrins. This allowed, for the first time, to extract and spectrally characterize the mono- and doubly-protonated forms (H<sub>3</sub>P<sup>+</sup> and H<sub>4</sub>P<sup>2+</sup>) of each ligands in the AN–HClO<sub>4</sub> system. The analysis of the spectral changes of the monoamino derivative led to identify three stages of the protonation, which first involves the nitrogen atom of the periphery substituent (p<i>K</i><sub>b</sub> = 13.26) and then the central nitrogen atoms of the macrocycle (p<i>K</i><sub>b1</sub> = 11.50; p<i>K</i><sub>b2</sub> = 9.65; p<i>K</i><sub>b1,2</sub> = 21.15). The relative stability of the first intermediate is assumed to be caused by charge delocalization. The electron-donor nature of the solvent in the DMSO–KOH [222] system led to the leveling of the ionization constants for the first and second stages, which allowed us to determine only the total values for the porphyrins studied. The successive stages of acid–base interactions were analyzed in the article.</p><h3>Graphical abstract</h3>\n <figure><div><div><div><picture><source><img></source></picture></div></div></div></figure>\n </div>","PeriodicalId":638,"journal":{"name":"Journal of Inclusion Phenomena and Macrocyclic Chemistry","volume":"102 5-6","pages":"493 - 505"},"PeriodicalIF":2.3000,"publicationDate":"2022-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"2","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Inclusion Phenomena and Macrocyclic Chemistry","FirstCategoryId":"92","ListUrlMain":"https://link.springer.com/article/10.1007/s10847-022-01131-8","RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Agricultural and Biological Sciences","Score":null,"Total":0}
引用次数: 2
Abstract
The directed synthesis of asymmetrically substituted porphyrins—tetraphenylporphyrine derivatives containing amino acid residues as a functional group, which can be used as “anchor” groups, for incorporation into the structure of a protein molecule, was carried out. The obtained compounds were characterized by a number of spectral methods confirming their structure and purity. Their base and acid ionization constants in the AN–HClO4 and DMSO–potassium cryptate (KOH[222])—systems were measured by spectrophotometric titration. It was found that the asymmetric substitution architecture contributed to the stabilization of the protonated forms of porphyrins. This allowed, for the first time, to extract and spectrally characterize the mono- and doubly-protonated forms (H3P+ and H4P2+) of each ligands in the AN–HClO4 system. The analysis of the spectral changes of the monoamino derivative led to identify three stages of the protonation, which first involves the nitrogen atom of the periphery substituent (pKb = 13.26) and then the central nitrogen atoms of the macrocycle (pKb1 = 11.50; pKb2 = 9.65; pKb1,2 = 21.15). The relative stability of the first intermediate is assumed to be caused by charge delocalization. The electron-donor nature of the solvent in the DMSO–KOH [222] system led to the leveling of the ionization constants for the first and second stages, which allowed us to determine only the total values for the porphyrins studied. The successive stages of acid–base interactions were analyzed in the article.
期刊介绍:
The Journal of Inclusion Phenomena and Macrocyclic Chemistry is the premier interdisciplinary publication reporting on original research into all aspects of host-guest systems. Examples of specific areas of interest are: the preparation and characterization of new hosts and new host-guest systems, especially those involving macrocyclic ligands; crystallographic, spectroscopic, thermodynamic and theoretical studies; applications in chromatography and inclusion polymerization; enzyme modelling; molecular recognition and catalysis by inclusion compounds; intercalates in biological and non-biological systems, cyclodextrin complexes and their applications in the agriculture, flavoring, food and pharmaceutical industries; synthesis, characterization and applications of zeolites.
The journal publishes primarily reports of original research and preliminary communications, provided the latter represent a significant advance in the understanding of inclusion science. Critical reviews dealing with recent advances in the field are a periodic feature of the journal.