NH tautomerization of 2,7,18,23-tetramethyl-3,8,12,13,17,22-hexaethylsapphyrin

Rachlewicz, Krystyna; Latos‐Grażyński, Lechosław; Gebauer, A.; Vivian, Anne E.; Sessler, Jonathan L.

doi:10.1039/a901983i

Cited by 24 publications

(21 citation statements)

References 35 publications

(30 reference statements)

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“…Flexible conformational changes of meso-aryl substituted sapphyrins were revealed by Latos-Grażyń ski and co-workers both for the neutral and protonated states. [53] With regard to conformational dependence on the aromatic versus antiaromatic characters, Möbius aromaticity has become an interesting topic, since 4n p expanded porphyrins usually adopt twisted figure-eight conformations but prefer twisted Möbius conformations upon appropriate stimuli (Section 7).…”

Section: Conformational Flexibilitymentioning

confidence: 99%

Expanded Porphyrins: Intriguing Structures, Electronic Properties, and Reactivities

2011

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The chemistry of expanded porphyrins, which are higher homologues of porphyrins, has been intensively explored for the last three decades. Expanded porphyrins exhibit structures, electronic properties, coordination chemistry, and reactivities that are entirely different from those of porphyrins. Through these studies, it has become increasingly apparent that expanded porphyrins are attractive in views of aromaticity and multimetal coordination, or as functional dyes, nonlinear optical materials, ion receptors, or stable organic radicals. As such, we have continuously witnessed the emergence of expanded porphyrins that exhibit unprecedented structures and properties, as is highlighted by the facile realization of Möbius aromatic and even antiaromatic systems with twisted molecular structures. In this Review, the recent progress of the chemistry of expanded porphyrins after the seminal Review by Sessler and Seidel in 2003 is presented.

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Section: Conformational Flexibilitymentioning

confidence: 99%

Expanded Porphyrins: Intriguing Structures, Electronic Properties, and Reactivities

2011

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“…Following this methodology, discrete information on the present tautomers for a number of unsymmetrically mono- [116], di- [115,116], tris- [117], and tetrasubstituted porphyrins [118], N-confused (by N-alkylation) porphyrins [119][120][121], decaalkylated sapporphyrins [122], and natural chlorin derivatives [123] was derived.…”

Section: Tautomerism In Porphyrinsmentioning

confidence: 99%

NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

Kleinpeter

2013

Tautomerism

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“…tetraphenylsapphyrin (TPSH 3 ) [21,22]. The decaalkyl substituted sapphyrins typically demonstrate roughly planar arrangement with pyrrole nitrogens oriented toward the center of the macrocycle [23,24]. Contrarily, in the case of tetraphenylsapphyrin (TPSH 3 ), the unusual macrocyclic skeleton with the inverted pyrrole ring lying opposite to the bipyrrolic unit was detected.…”

Section: Introductionmentioning

confidence: 95%

A transient form of 2-aza-21-carbaporphyrin prearranged for fusion: DFT studies

Szterenberg

Latos‐Grażyński

2001

J. Porphyrins Phthalocyanines

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ABSTRACT:The formation mechanism of the fused porphyrin (CTPPH-NF) involves a rotation of the N(2) pyrrole ring of 2-aza-21-carba-5,10,15,20-tetraarylporphyrin (CTPPH 2 ) which is subsequently followed by formation of the C(3)-N(24) bond to yield the macrocycle with the fused pyrrole tripentacyclic ring. To approach the problem of the relative stability of the prearranged transient species theoretical investigations have been performed applying density functional theory (DFT). The molecular structures and electronic energy have been studied for idealized 2-aza-21-carbaporphyrin (CPPH 2 ) and porphyrin (PH 2 ) macrocycles created by a replacement of phenyl or other substituents with hydrogen or methyl groups. The following forms of 2-aza-21-carbaporphyrin and porphyrin were studied: CPH 2 -I, 2-NH-CPH-I and PH 2 -I in relation to CPH 2 -P, 2-NH-CPH-P and PH 2 -P, respectively (P indicates regular geometry (N(21) or C(21) located in the inner perimeter) and I indicates inverted geometry (N(21) or C(21) located in the outer perimeter).A p delocalization exists through the inverted macrocycles: PH 2 -I, CPH 2 -I and 2-NH-CPH-I. The B3LYP/6-31G** optimized bond distances of I macrocycles reproduce the pattern of the P counterparts. The B3LYP/6-31G**//B3LYP/6-31G** calculated energy differences between the P and I structures are very similar for two considered 2-aza-21-carbaporphyrin tautomers: CPH 2 -P → CPH 2 -I, 18.50 kcal mol À1 , 2-NH-CPH-P → 2-NH-CPH-I, 17.55 kcal mol À1 ; but essentially different for the regular porphyrin PH 2 -P → PH 2 -I, 45.56 kcal mol À1 . The methyl substitution at the 21-carbon or 5 and 20 meso positions preserved the order of stability as the calculated energy differences equal

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NH tautomerization of 2,7,18,23-tetramethyl-3,8,12,13,17,22-hexaethylsapphyrin

Cited by 24 publications

References 35 publications

Expanded Porphyrins: Intriguing Structures, Electronic Properties, and Reactivities

Expanded Porphyrins: Intriguing Structures, Electronic Properties, and Reactivities

NMR Spectroscopic Study of Tautomerism in Solution and in the Solid State

A transient form of 2-aza-21-carbaporphyrin prearranged for fusion: DFT studies

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