Feb, 2017
Protonation behavior of thiaporphyrin and thiabenzoporphyrin
TETRAHEDRON
- ,
- ,
- ,
- ,
- Volume
- 73
- Number
- 6
- First page
- 794
- Last page
- 801
- Language
- English
- Publishing type
- Research paper (scientific journal)
- DOI
- 10.1016/j.tet.2016.12.067
- Publisher
- PERGAMON-ELSEVIER SCIENCE LTD
The protonation behavior of bicyclo[2.2.2]octadiene (BCOD)-fused thiaporphyrin and thiabenzoporphyrin was examined by titration with trifluoroacetic acid. Neutral, monorotonated, and diprotonated species of thiaporphyrins were easily detected by UV-vis spectral measurement. The first (K-1) and second (K-2) equilibrium constants were found to be K-1 = 520 and K-2 approximate to 7.1 for BCOD-fused thiaporphyrin and K-1 = 1.4 x 10(4) and K-2 approximate to 1.4 for thiabenzoporphyrin. The difference between K-1 and K-2 values of thiaporphyrins is larger than that observed for porphyrins (N-4-porphyrins). The main contributing conjugation pathways for thiaporphyrins in both protonated species were investigated by NICS and AICD quantum calculations using their atomic geometries obtained by X-ray structural analysis. The 18 pi-conjugation pathways of the neutral, monoprotonated, and diprotonated species thiaporphyrins were found to contain 18, 19, and 20 atoms, respectively. Results of H-1 NMR studies also support the major contributing pathways. (C) 2016 Elsevier Ltd. All rights reserved.
- Link information
- ID information
-
- DOI : 10.1016/j.tet.2016.12.067
- ISSN : 0040-4020
- Web of Science ID : WOS:000393003500017