Assessing Electronically Excited States of Cobalamins …
235
Fig. 8 Molecular structures of protonated free base corrins obtained from DFT/B3LYP calculations.
Reprinted with permission from [32]. Copyright 2003 American Chemical Society
DFT method [32]. The electronic spectrum of both forms of the metal-free corrins
was simulated using TD-DFT B3LYP and was compared to the Abs spectrum of
dicyanocobinamide and the synthetic 1,2,2,7,7,12,12-heptamethylcorrin, which is
very similar to Toohey’s [88] isolated compound. For the calculations in this study,
structures with all possible configurations of two protons among the four nitrogen
atoms of the corrin macrocycle were considered, leading to four protonated structures
under analysis. These were designated based on the protonated nitrogens as follows,
Ip for N23 and N21, IIp for N21 and N24, IIIp for N22 and N23, and IVp for N21
235
Fig. 8 Molecular structures of protonated free base corrins obtained from DFT/B3LYP calculations.
Reprinted with permission from [32]. Copyright 2003 American Chemical Society
DFT method [32]. The electronic spectrum of both forms of the metal-free corrins
was simulated using TD-DFT B3LYP and was compared to the Abs spectrum of
dicyanocobinamide and the synthetic 1,2,2,7,7,12,12-heptamethylcorrin, which is
very similar to Toohey’s [88] isolated compound. For the calculations in this study,
structures with all possible configurations of two protons among the four nitrogen
atoms of the corrin macrocycle were considered, leading to four protonated structures
under analysis. These were designated based on the protonated nitrogens as follows,
Ip for N23 and N21, IIp for N21 and N24, IIIp for N22 and N23, and IVp for N21