Synthesis of 5,10-bis(Trifluoromethyl) Substituted beta-Octamethylporphyrins and Central-Metal-Dependent Solvolysis of Their meso-Trifluoromethyl Groups

摘要

5,10-Bistrifluoromethyl substituted -octamethylporphyrins were synthesized via a scrambling side reaction of a dipyrromethane precursor in the presence of a large excess of trifluoroacetic acid. Compared with the trans-analogs, the cis-analogs of meso-trifluoromethyl -octaalkylporphyrin showed more red-shifted absorption bands. These meso-trifluoromethyl derivatives of -octaalkylporphyrins underwent smooth metalation, similar to other common porphyrins, however, the corresponding zinc complexes underwent a type of solvolysis, whereby the trifluoromethyl groups were converted into methoxycarbonyl groups by the methanol used as solvent. UV-visible absorption spectra and X-ray crystal structure analyses revealed that the presence of a methoxycarbonyl substituent did not influence the deformation of the molecular framework and its absorption properties; this is because the methoxycarbonyl has a planar and perpendicular geometry, as opposed to the relatively bulky trifluoromethyl substituent.