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| Content Provider | World Health Organization (WHO)-Global Index Medicus |
|---|---|
| Author | Blusch, Lina K. Hemberger, Yasmin Witterauf, Franziska Meyer, Franc Pröpper, Kevin Bringmann, Gerhard Dittrich, Birger Brückner, Christian John, Michael |
| Description | Author Affiliation: Blusch LK ( Institute of Inorganic Chemistry, University of Göttingen, Tammannstr. 4, 37077 Göttingen, Germany.) |
| Abstract | The 3+3-type synthesis of a pyrazole-based expanded porphyrin $22 H_{4},$ a hexaphyrin analogue named Siamese-twin porphyrin, and its homobimetallic diamagnetic nickel(II) and paramagnetic copper(II) complexes, $22 Ni_{2}$ and $22 Cu_{2},$ are described. The structure of the macrocycle composed of four pyrroles and two pyrazoles all linked by single carbon atoms, can be interpreted as two conjoined porphyrin-like subunits, with the two opposing pyrazoles acting as the fusion points. Variable-temperature 1D and 2D NMR spectroscopic analyses suggested a conformationally flexible structure for $22 H_{4}.$ NMR and UV/Vis spectroscopic evidence as well as structural parameters proved the macrocycle to be non-aromatic, though each half of the molecule is fully conjugated. UV/Vis and NMR spectroscopic titrations of the free base macrocycle with acid showed it to be dibasic. In the complexes, each metal ion is coordinated in a square-planar fashion by a dianionic, porphyrin-like $\{N_{4}\}$ binding pocket. The solid-state structures of the dication and both metal complexes were elucidated by single-crystal diffractometry. The conformations of the three structures are all similar to each other and strongly twisted, rendering the molecules chiral. The persistent helical twist in the protonated form of the free base and in both metal complexes permitted resolution of these enantiomeric helimers by HPLC on a chiral phase. The absolute stereostructures of $22 H_{6}^{2+},$ $22 Ni_{2},$ and $22 Cu_{2}$ were assigned by a combination of experimental electronic circular dichroism (ECD) investigations and quantum-chemical ECD calculations. The synthesis of the first member of this long-sought class of expanded porphyrin-like macrocycles lays the foundation for the study of the interactions of the metal centers within their bimetallic complexes. |
| ISSN | 09476539 |
| e-ISSN | 15213765 |
| Journal | Chemistry - A European Journal |
| Issue Number | 19 |
| Volume Number | 19 |
| Language | English |
| Publisher | Wiley-VCH;ChemPubSoc Europe |
| Publisher Date | 2013-05-03 |
| Publisher Place | Germany |
| Access Restriction | Open |
| Subject Keyword | Chemistry |
| Content Type | Text |
| Resource Type | Article |
| Subject | Organic Chemistry Catalysis |
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