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Aromatic pathways in thieno-bridged porphyrins: understanding the influence of the direction of the thiophene ring on the aromatic character.
- Source :
-
Molecular Physics . Jul2013, Vol. 111 Issue 9-11, p1364-1372. 9p. - Publication Year :
- 2013
-
Abstract
- Magnetically induced current densities have been investigated for some recently synthesised thieno-bridged porphyrins. The aim of the study is to understand the influence of the direction of the thieno bridge on the aromatic character of the molecules. The calculated ring-current susceptibilities for two tautomers of 2,3- and 3,4-thieno-bridged porphyrins as well as of the corresponding Zn-containing compounds show that the molecules are all aromatic according to the ring current criterion. The ring-current susceptibilities of 16.2 nA/T and 20.2 nA/T around the porphyrin ring of the two tautomers of 2,3-thieno-bridged porphyrin are somewhat weaker than the ring-current susceptibilities of 22.8 nA/T and 23.8 nA/T obtained for the two tautomers of 3,4-thieno-bridged porphyrin. For 2,3-thieno-bridged porphyrin, the positions of the inner hydrogens affect the ring-current susceptibility more than for 3,4-thieno-bridged porphyrin. The current pathways of the Zn porphyrinoids are a superposition of the pathways of the twotranstautomers of the corresponding free-base porphyrinoids. The current-density calculations explain the different aromatic character of 2,3-thieno-bridged and 3,4-thieno-bridged porphyrins. Current-density calculations on tetra-2,3-thieno-bridged and tetra-3,4-thieno-bridged porphyrins yielded similar current pathways as obtained for mono-substituted thieno-bridged porphyrins. Tetra-2,3-thieno-bridged porphyrin is practically non-aromatic since it sustains a very weak ring current of 2.6 nA/T. The calculated ring-current susceptibilities for tetra-3,4-thieno-bridged porphyrin is 13.2 nA/T, which can be compared to the ring-current susceptibilities of 11.8 and 27.5 nA/T for benzene and free-base porphyrin, respectively. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00268976
- Volume :
- 111
- Issue :
- 9-11
- Database :
- Academic Search Index
- Journal :
- Molecular Physics
- Publication Type :
- Academic Journal
- Accession number :
- 89571323
- Full Text :
- https://doi.org/10.1080/00268976.2013.794397