| Autor: |
Thomas, KE, McCormick, LJ, Vazquez-Lima, H, Ghosh, A |
| Jazyk: |
angličtina |
| Rok vydání: |
2017 |
| Zdroj: |
Thomas, KE; McCormick, LJ; Vazquez-Lima, H; & Ghosh, A. (2017). Stabilization and Structure of the cis Tautomer of a Free-Base Porphyrin. Angewandte Chemie-International Edition, 56(34), 10088-10092. doi: 10.1002/anie.201701965. Lawrence Berkeley National Laboratory: Retrieved from: http://www.escholarship.org/uc/item/25v7422s |
| Popis: |
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Single-crystal X-ray analysis of the β-heptakis(trifluoromethyl)-meso-tetrakis(p-fluorophenyl)porphyrin, H2[(CF3)7TpFPP], has revealed the first example of a stable cis tautomer of a free-base porphyrin, the long-postulated intermediate of porphyrin tautomerism. The stability of the unique molecule appears to reflect a dual origin: a strongly saddled porphyrin skeleton, which alleviates electrostatic repulsion between the two NH protons, and two polarization-enhanced, transannular N−H⋅⋅⋅O−H⋅⋅⋅N hydrogen bond chains, each involving a molecule of water. DFT calculations suggest that the observed tautomer has a lower energy than the alternative, doubly hydrated trans tautomer by some 8.3 kcal mol−1. A fascinating prospect thus exists that H2[(CF3)7TpFPP]⋅2 H2O and cognate structures may act as supramolecular synthons, which, given their chirality, may even be amenable to resolution into optically pure enantiomers. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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