Subsequent treatment of H2TPP(CO2H)4 (tetra(p-carboxylic acid phenyl)porphyrin, 1) with an excess of oxalyl chloride and HNR2 afforded H2TPP(C(O)NR2)4 (R = Me, 2; iPr, 3) with yields exceeding 80%. The porphyrins 2 and 3 could be converted to the corresponding metalloporphyrins MTPP(C(O)NR2)4 (R = Me/iPr for M = Zn (2a, 3a); Cu (2b, 3b); Ni (2c, 3c); Co (2d, 3d)) by the addition of 3 equiv of anhydrous MCl2 (M = Zn, Cu, Ni, Co) to dimethylformamide solutions of 2 and 3 at elevated temperatures. Metalloporphyrins 2a-d and 3a-d were obtained in yields exceeding 60% and have been, as well as 2 and 3, characterized by elemental analysis, electrospray ionization mass spectrometry (ESIMS) and IR and UV-vis spectroscopy. Porphyrins 2, 2a-d and 3, 3a-d are not suitable for organic molecular beam deposition (OMBD), which is attributed to their comparatively low thermal stability as determined by thermogravimetric analysis (TG) of selected representatives.
Keywords: IR spectroscopy; UV–vis spectroscopy; electrospray ionization mass spectrometry; metalloporphyrin; porphyrin; thermogravimetry.