Preparation and characterization of the self-aggregated dimer of meso-p-hydroxyphenylporphyrin and studies on the self-aggregate reaction mechanism

In the paper, the self-aggregate properties of MHTPP [5-(4-hydroxyphenyl)-10,15,20-triphenylporphyrin] in the chloroform solutions have been investigated. The fresh solution of MHTPP strictly obeys Beerʹs law, while the deposited solution of MHTPP widely deviates from Beerʹs law. The Soret band of the UV–vis spectra was red-shifted from 420 nm of the fresh solution to 450 nm of the deposited solutions. The self-aggregate process of MHTPP was monitored using thin-layer chromatogram (TLC), UV–vis spectra, FTIR–IR spectra, mass spectra and 1H NMR. The results show that the self-aggregate process of MHTPP proceeded along with the effective charge-separation and proton-migration in the molecule. We speculate the self-aggregate mechanism of MHTPP by the results, which were monitored. Furthermore, the self-aggregate dimer of MHTPP was synthesized and the photophysical and electrochemical properties of the self-aggregated dimer were investigated.