The total electronic energy and nucleus-independent chemical shift (NICS) of 95 isomers of N-confused porphyrin (NCP) have been calculated by density functional theory (DFT) method. The aromatic nature and the stability were not directly related. The introduction of confusion decreases the stability ca. 18 kcal/mol per one confusion. The results were partially supported by the actual synthesis of cis-doubly N-confused porphyrin (N2CP). Furthermore, a different type of porphyrinoids, such as corrorin, oxyindolophyrin, and tripyrrinone, were obtained in the reactions of N2CP and NCP metal complexation. Electrochemistry and photochemistry of N2CP metal complexes were investigated and the potentiality for the use in water splitting and photodynamic therapy (PDT) were suggested.
On the other hand, a series of expanded porphyrins including, pentaphyrin, hexaphyrin, octaphyrins, and nonaphyrins, were synthesized and the structures were determined by the X-ray single crystal analyses. The normal type of meso-aryl substituted expanded porphyrins were non-planar but the doubly N-confused hexaphyrins were fond planar and could complex bis metal ions in the cavity maintaining the aromaticity.
The inner and outer metal coordination were found more general for the NCP. By using Pd(II) and Pt(II), unique double-decker type face-to-face dimers and the linear linked dimers were synthesized, respectively. When Zn(II) and Cd(II) were used, a new type of metal bridged dimers were formed. A versatile mode of NCP metal coordination were explicitly elucidated and opened the way for the metal assisted supramolecular assembly.