Synthesis under solvent free conditions and photoluminescence study of ionic intermediate sitting-atop complexes of meso-tetraarylporphyrins and phosphorus oxychloride

The reaction of meso-tetraarylporphyrins with phosphorus oxychloride was studied. The reaction product is the so-called intermediate sitting-atop (i-SAT) complex where two pyrrolic nitrogen atoms of the porphyrin core coordinate to the phosphorus atom and two protons on the pyrrolic nitrogen atoms remain. Selection of solvent free conditions is caused that the reaction does not progress until deprotonation step of porphyrin and stopped in the intermediate step for formation of the sitting-atop complex, [POCl2(H2t(X)pp)]Cl. The sitting-atop complexes were characterized by (1H, 31P, 13C) NMR, FT-IR, UV–vis and photoluminescence spectroscopy (PL), elemental analysis and electrical conductometry. Photoluminescence study of the complexes indicates that their emission spectra are different from those of free base porphyrins.

Graphical abstractThe reaction of meso-tetraarylporphyrins (H2t(X)pp) and POCl3 produced ionic intermediate sitting-atop complexes, [POCl2(H2t(X)pp)]Cl, that two nitrogen atoms of pyrrolenine in the porphyrins act as electron donors to d orbitals of phosphorus and two pyrrolic protons remain on the porphyrin macrocycle.H2t(X)pp + POCl3 → [POCl2(H2t(X)pp)]ClFigure optionsDownload full-size imageDownload as PowerPoint slide