UV-vis spectrophotometric titrations and vibrational spectroscopic characterization of meso-(p-Hydroxyphenyl)porphyrins

Hongwei Guo, Junguang Jiang, Yingyan Shi, Yuling Wang, Jiannan Liu, Shaojun Dong*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

34 Citations (Scopus)

Abstract

Sequentially spectrophotometric titrations by sodium hydroxide of meso-tetraphenylporphyrin derivatives bearing one, two, three, or four p-hydroxyl groups result in new types of spectra. The strong new bands appear in the visible region with splitting or broadening of the Soret band and its significant loss of oscillator strength. To understand the molecular origin of these phenomena, the Resonance Raman (RR) and Fourier Transform Infrared (FTIR) experiments are carried out. The results demonstrate that the charges of the deprotonated para-hydroxy substituted meso-tetraphenylporphyrins are localized on the substituents, not delocalized into the π system of the porphyrin macrocycles and that the ground states of the macrocycles remain essentially unperturbed. Both the related behavior of diprotonated tetrakis(p-(dimethylamino)phenyl) porphyrin and protonated Schiff base porphyrins show that the new bands considered as hyperporphyrin spectra are due to π(phenoxide anion) → π* (porphyrin) transitions, where π is an orbital on the phenoxide anion substitutent and π* is a LUMO on the porphyrin.

Original languageEnglish
Pages (from-to)10185-10191
Number of pages7
JournalJournal of Physical Chemistry B
Volume108
Issue number28
Publication statusPublished - 15 Jul 2004
Externally publishedYes

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