This work was supported by grant nos. 262229 and 324139 of the Research Council of Norway (AG) and grant nos. 129270 and 132504 of South African National Research Foundation (JC).
The Journal of Physical Chemistry. A
Porphyrins -- Analysis, Porphyrins -- Synthesis
A detailed TDDFT study (with all-electron STO-TZ2P basis sets and the COSMO solvation model) has been carried out on the effect of diprotonation on the UV-vis-NIR spectra of free-base tetraphenylporphyrin and tetrakis(-aminophenyl)porphyrin. The diprotonated forms have been modeled as their bis-formate complexes, i.e., as so-called porphyrin diacids. The dramatic redshift of the Q-band of the TAPP diacid has been explained in terms of an elevated "a" HOMO and lowered LUMOs, both reflecting infusion of aminophenyl character into the otherwise classic Gouterman-type frontier MOs. The exercise has also yielded valuable information on the performance of different exchange-correlation functionals. Thus, the hybrid B3LYP functional was found to yield a substantially better description of key spectral features, especially the diprotonation-induced redshifts, than the pure OLYP functional. Use of the range-separated CAMY-B3LYP functional, on the other hand, did not result in improvements relative to B3LYP.
© 2021 The Authors. Published by American Chemical Society
Locate the Document
Conradie, J., Wamser, C. C., & Ghosh, A. (2021). Understanding Hyperporphyrin Spectra: TDDFT Calculations on Diprotonated Tetrakis( p -aminophenyl)porphyrin. The Journal of Physical Chemistry A, acs.jpca.1c06621. https://doi.org/10.1021/acs.jpca.1c06621