UV-vis absorption spectra of Sn(IV)tetrakis(4-pyridyl) porphyrins on the basis of axial ligation and pyridine protonation

Characterization of the UV-Visible absorption spectra of manganese(III) porphyrins with time-dependent density functional theory calculations

Mn(III) porphyrins display a unique UV–Vis spectrum: compared to the free-base and other metalloporphyrins, a strong red shift of the Soret-band and several extra bands can be observed in their spectra. To understand this behavior, we have recorded the UV–Vis spectra of differently substituted water-soluble Mn(III) porphyrins and conducted extensive theoretical investigations using time-dependent density functional theory. The calculated optical transitions, using the O3LYP functional, agree well with the measured absorption bands. According to the spectral interpretation, the Soret-band involves a mixture of L–L and ligand-to-metal charge transfer excitations, while the Q-bands and the higher-energy bands in the UV region correspond to pure LMCT as well as to ligand to metal-ligand mixed orbital excitations. The impact of the explicit and implicit water solvent on the spectral features is also discussed.

A Theoretical Study of Metalloporphyrin-Based Fluorescent Array Sensor using Density Functional Theory

The influences of metal atoms on optimized geometry structures, relative energies, frontline molecular orbitals, and binding energies of metalloporphyrin-based fluorescent array sensor were systematically investigated by density functional theory (DFT) at B3LYP/LAN2DZ level. DFT calculated results reveal that the selected metal atoms in the center of the metalloporphyrin plane provide difference performances of metalloporphyrin-based fluorescent array sensor for the rapid determination of trimethylamine. The calculated binding energies have displayed in the following order at the most stable states: zinc porphyrin (ZnP) < copper porphyrin (CuP) < silver porphyrin (AgP) < iron porphyrin (FeP) < tin porphyrin (SnP) < cobalt porphyrin (CoP) < ruthenium porphyrin (RuP) < manganese porphyrin (MnP). Therefore, this theoretical study provides a design mechanism for how to choose a proper metal atom for low or high concentration trimethylamine. This research also suggests that theoretical results may be useful for the rapid detection of food containing trimethylamine.