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Title: Corrole NH Tautomers: Spectral Features and Individual Protonation
Authors: Ivanova, Yulia B.
Savva, Vadim A.
Mamardashvili, Nugzar Z.
Starukhin, Aleksander S.
Ngo, Thien H.
Dehaen, Wim
MAES, Wouter 
Kruk, Mikalai M.
Issue Date: 2012
Source: JOURNAL OF PHYSICAL CHEMISTRY A, 116 (44), p. 10683-10694
Abstract: Protonation of a free-base meso-pyrimidinyl-substituted AB(2)-corrole (H(3)AB(2)) in ethanol solution by stepwise addition of sulfuric acid has been studied in the temperature range from 293 to 333 K. The formation rate of protonated species was found to depend profoundly on the temperature at which the titration was undertaken. Two steps in the titration curve were identified at temperatures around 293-298 K, whereas one-step formation of protonated species was found to occur at temperatures above 308 K. The protonation product was the same in both cases, i.e., H(4)AB(2)(+) corrole, protonated at the macrocycle core nitrogen atoms. The two steps in the protonation kinetics at lower temperatures were attributed to protonation of individual tautomers of the free-base H(3)AB(2) corrole. To the best of our knowledge, this is the first well-illustrated (spectrophotometric) observation of individual properties of corrole NH tautomers in fluid solution. Concomitant increase in the NH tautomerization rate with increasing temperature is proposed to account for the one-step protonation. Evidences for the role of individual corrole NH tautomers in the protonation process as well as their optical features are discussed based on spectroscopic results and simulation data.
Notes: [Ngo, Thien H.; Dehaen, Wim; Maes, Wouter] Katholieke Univ Leuven, Dept Chem, B-3001 Louvain, Belgium. [Ivanova, Yulia B.; Mamardashvili, Nugzar Z.] Russian Acad Sci, Inst Solut Chem, Ivanovo 153045, Russia. [Savva, Vadim A.; Starukhin, Aleksander S.; Kruk, Mikalai M.] Natl Acad Sci, BI Stepanov Phys Inst, Minsk 220072, Byelarus. [Ngo, Thien H.] Free Univ Berlin, Inst Chem & Biochem Organ Chem, D-14195 Berlin, Germany. [Maes, Wouter] Hasselt Univ, Inst Mat Res IMO IMOMEC, B-3590 Diepenbeek, Belgium.;
Keywords: Chemistry, Physical; Physics, Atomic, Molecular & Chemical; free-base corroles; core-modified corroles; mesosubstituted corroles; efficient synthesis; versatile synthon; coupling reaction; nonaqueous media; singlet oxygen; metal-free; porphyrins
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ISSN: 1089-5639
e-ISSN: 1520-5215
DOI: 10.1021/jp305325e
ISI #: 000310769100005
Category: A1
Type: Journal Contribution
Validations: ecoom 2013
Appears in Collections:Research publications

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