DFT/TDDFT Study of Lanthanide^III Mono- and Bisporphyrin Complexes

Abstract

Electronic structure, molecular structure, and electronic spectra of lanthanide III mono-and bisporphyrin complexes are investigated using a DFT/TDDFT method. These complexes include YbP (acac), YbP 2 , [YbP 2 ] + , YbHP 2 , and [YbP 2 ] − (where P = porphine and acac = acetylacetonate). To shed some light on the origin of the out-of-plane displacement of Yb in YbP(acac), unligated model systems, namely planar D 4h and distorted C 4v YbP, were calculated. For comparison, the calculations were also extended to include the Ce IV P 2 and [Ce IV P 2 ] + systems. Even without an axial ligand, the lanthanide atom lies considerably above the porphyrin plane; the distortion of the YbP molecular structure from a planar D 4h to the non-planar C 4v symmetry leads to a considerable energy lowering. The axial ligand makes the metal out-of-plane displacement even larger, and it also changes the redox properties of the lanthanide mono-porphyrin. The ground state configurations of YbP 2 and YbHP 2 were determined by considering several possible low-lying states. YbP 2 is confirmed to be a singlehole radical. The special redox properties of the bis-porphyrin complexes can well be accounted for by the calculated ionization potentials and electron affinities. The TDDFT results provide a clear description of the UV-visible and near-IR absorption spectra of the various lanthanide porphyrins.

Applications of Density Functional Theory (DFT) to Investigate the Structural, Spectroscopic and Magnetic Properties of Lanthanide(III) Complexes

“…This study showed that different ligand C-H vibrations contribute to the quenching of the Er III luminescence, the calculated emission lifetime being in good agreement with the experimental value [249]. Finally, TDDFT calculations including the 4f electrons in the valence space were successfully used to calculate the absorption spectra Ln III mono-and bisporphyrin complexes [250], and Lu III bisphthalocyanines [251].…”

Impressive near-infrared brightness and singlet oxygen generation from strategic lanthanide–porphyrin double-decker complexes in aqueous solution

“…Previous calculations of the energy levels of double-decker complexes have shown poor agreement with experiments 47,48 . Herein, the absorption spectrum was modeled from the optimized structure by two programs.…”

Lanthanum and abscisic acid coregulate chlorophyll production of seedling in switchgrass

“…The quantum chemical methods provide an effective way to investigate these reactions at molecular level. With density functional theory (DFT) and time-dependent density functional theory (TD-DFT), Liao et al [35] successfully predicted the molecular structures of lanthanide mono-and bisporphyrin complexes. Yin [36] calculated the free energies of deprotonated and protonated species of prophyrin, and showed which process was thermodynamically favorable.…”