Synthesizing Tetraphenylporphyrins and Metalloporphyrins using microwave and ultrasonic reactors

Abstract

Tetraphenylporphyrin (TPP) is a macrocyclic molecule found in biological compounds. TPP's UV-Vis spectrum ranges from 380-500 nanometers. Metalloporphyrins (MeP) are considered “bioinspired oxidation catalysts” and are synthesized from TPP and metal anhydrous salts. Therefore, hypothesizing that the UV-Vis spectrum of the MeP will be altered by the type of benzaldehyde (electron-donating and electron-withdrawing groups attached to the benzene ring) which are added to the TPP ligand during the MeP synthesis reaction. In this project investigated solvent-free conditions, first with a silica gel support and then without it. The TPPs were produced in a Chemical Explorer Microwave (CEM) Reactor with a commercial 950W/1000W microwave oven. The conventional reflux method and an ultrasonic reactor were used to develop the MePs. TPPs were synthesized with substituted and unsubstituted benzaldehydes to investigate the effect of electron-donating and electron-withdrawing groups on the complex synthesis and the UV shift. The UV-Vis spectra for each MeP confirmed the formation of complexes with transition and p-block metals. The data displayed that the Tin MeP showed a red-shift UV-Vis spectrum (446 nm) compared to the initial TPP (417 nm). Complexation of Tin with the 4-chloroTPP displayed a maximum peak at 473 nm. This reaffirms that the electron-withdrawing benzaldehydes worked better than the electron-donating when added to the TPP. Thus, causing the UV-Vis spectra to have a red shift compared to the initial product.