Preparations of Core H2O-Bound 5, 10, 15, 20-Tetrakis-4-chlorophenyl Porphyrin, P 1, and O-Methylation of Phenol and Its P-Substituted Analogues

Abstract

The treatment of a dichloromethane solution of 5, 10, 15, 20-tetrakis-4-chlorophenyl porphyrin, P1, with methanolic solutions of each of phenol, p-amino phenol, and p-nitro phenol for just 1 h results in the formation of water-molecule-bound amorphous solids of P1. In addition to the straightforward access to the H2O-molecule-coordinated species of P1 thus produced, the another chief advantage of this synthetic strategy is the successful recoveries of anisole, p-amino anisole, and p-nitro anisole at the end of the reactions. The present work therefore further reports the use of P1 as an efficient catalyst for the selective O-methylation of phenols using methanol as an environmentally friendly methylating agent. The H2O-bound amorphous solids of P1 exhibit higher-intensity absorption as well as photoluminescence emission bands in dichloromethane compared with the parent crystalline form. Further, the measurement of the solid-state emission properties of both the crystalline and amorphous forms indicates quenching of fluorescence bands corresponding to amorphous solids in comparison with that of parent crystalline form. The crystalline form of P1 and the H2O-bound amorphous solids were further studied by scanning electron microscope/transmission electron microscope (SEM/TEM), powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and thermal analysis techniques. The results of these studies indicate change in morphological and structural features, surface areas, porosities, and thermal robustness upon core coordination of water molecules with the macrocyclic rings of P1.