Electronic Structure of Metallophthalocyanines, MPc (M = Fe, Co, Ni, Cu, Zn, Mg) and Fluorinated MPc

We
compute the electronic structure and optical excitation energies
of metal-free and transition-metal phthalocyanines (H2Pc
and MPc for M = Fe, Co, Ni, Cu, Zn, Mg) using density functional theory
with optimally tuned range-separated hybrid functionals (OT-RSH).
We show that the OT-RSH approach provides photoemission spectra in
quantitative agreement with experiments as well as optical band gaps
within 10% of their experimental values, capturing the interplay of
localized d-states and delocalized π–π* states
for these organometallic compounds. We examine the tunability of MPcs
and H2Pc through fluorination, resulting in quasi-rigid
shifts of the molecular orbital energies by up to 0.7 eV. Our comprehensive
data set provides a new computational benchmark for gas-phase phthalocyanines,
significantly improving upon other density-functional-theory-based
approaches.