Synthesis, Reactivity and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins
The synthesis, reactivity and full characterization of a series of meso-tetraalkyl porphyrins and metalloporphyrins with R ≡ n-butyl (6), 2-methyl-propyl (7), isopropyl (8), 1-ethyl-propyl (10) and tert-butyl (11) groups are reported. Derivatives of the last of these show considerably bathochromically shifted absorption bands and the crystal structure of Zn(II)11(pyr) exhibits a severely ruffled macrocycle conformation. Systematic crystallographic studies of the porphyrins showed that the free base porphyrins with R ≡ n-butyl (H26), 2-methyl-propyl (H27) and 1-ethyl-propyl (H210) are planar. A larger conformational variety was found for the metal complexes. While most Ni(II) derivatives and Pd(II)8 showed a ruffled macrocycle conformation with a degree of ruffling exceeding that of meso-unsubstituted porphyrins, both planar and non-planar forms were found for the related Cu(II) derivatives. The Zn(II) complexes of porphyrins with isopropyl or 1-ethyl-propyl exhibited conformations with variable degree of distortion. Together with comparative structures from the literature, this study provides experimental evidence that considerable conformational flexibility exists for meso-alkylporphyrins with substituents less bulky than tert-butyl groups. Copyright © 1999 John Wiley & Sons, Ltd.
Publication Source (Journal or Book title)
Journal of Porphyrins and Phthalocyanines
Senge, M., Bischoff, I., Nelson, N., & Smith, K. (1999). Synthesis, Reactivity and Structural Chemistry of 5,10,15,20-Tetraalkylporphyrins. Journal of Porphyrins and Phthalocyanines, 3 (2), 99-116. https://doi.org/10.1002/(SICI)1099-1409(199902)3:2<99::AID-JPP109>3.3.CO;2-Y