Download PDF
Synfacts 2011(12): 1301-1301  
DOI: 10.1055/s-0031-1289390
Synthesis of Materials and Unnatural Products
© Georg Thieme Verlag Stuttgart ˙ New York

An All-Organic Porphyrin and its Properties

Contributor(s):Timothy M. Swager, Sébastien Rochat
T. P. Vaid*
University of Alabama, Tuscaloosa, USA
A Porphyrin with a C=C Unit at Its Center
J. Am. Chem. Soc.  2011,  133:  15838-15841  
Google Scholar
Further Information

Publication History

Publication Date:
18 November 2011 (online)

 PDF Download Permissions and Reprints

Key words

porphyrins - macrocycles - aromaticity

Significance

Reaction of cobalt porphyrin 1 with diiodoacetylene in the presence of FeCl3 followed by treatment with K2CO3 affords compound 2, which is reduced with SmI2 to form porphyrin 3. Characterization of this neutral C=C porphyrin reveals alternating single and double C-C bonds, owing to the antiaromatic properties of the compound. Further, cyclic voltammetry measurements indicate an easy oxidation of 3 to its dicationic, 18π-electron aromatic form. Chemical oxidation of 3 in the presence of AgOTf affords ionic species 4. NMR measurements and DFT calculations confirm the aromatic character of 4, that does not possess alternating single and double C-C bonds.

Comment

Although the typical aromatic character of porphyrins is preserved in compound 4, its electronic structure significantly differs from that of classical metalloporphyrins. In particular, the UV/Vis absorbance spectrum of 4 features several intense bands where the single Soret band is ­usually observed for porphyrins. Such properties make this new type of porphyrins of potential interest for light-harvesting systems.

   Permissions and Reprints