Novel triazaporphyrins were synthesized using 1,9-dibromodipyrromethene as a key starting material. These triazaporphyrins exhibit comparatively intense Soret and Q bands in the UV/vis region due to their hybrid properties between porphyrins and phthalocyanines.
A novel triphyrin was unexpectedly formed as a major by-product in the synthesis of meso-aryl-substituted dibenzo-5,10,15-triazaporphyrin from meso-aryl-substituted 1,9-dibromodipyrromethene and 5,6-diaryl-substituted 1,3-diiminoisoindoline in the presence of N,N-dimethylaminoethanol (DMAE). X-ray single crystal diffraction analysis elucidated that the terminal α-positions of this triphyrin were bridged by an N-methylaminoethoxy chain, which plausibly originated from DMAE during the reaction. The same compound was also obtained as a major product in the reaction of DMAE and meso-aryl-substituted 1,9-dibromodipyrromethene. Its unique properties, such as conformational flexibility of the bridging moiety and broad absorption in the visible region, were also revealed by 1 H NMR and UV-vis absorption spectroscopies.
Despite significant interest, the chiroptical properties of subporphyrins have rarely been investigated because chiral subporphyrins are elusive. Here, inherently chiral subporphyrins are elaborated by forming a fused pyran ring at the periphery of an A2B-type meso-aryl-substituted subporphyrin. Their circular dichroism (CD) properties are largely affected by the peripheral substituents and the dihedral angles between the meso-aryl substituents and the subporphyrin core: the β-perbromo subporphyrin with an orthogonal arrangement of the meso-phenyl substituents to the subporphyrin core exhibits weak CD signals corresponding to the Q bands, whereas the unsubstituted species with smaller dihedral angles shows relatively intense CD signals. A detailed structure–property relationship of these chiral subporphyrins was elucidated by time-dependent (TD) DFT calculations. This study reveals that the CD properties of chiral subporphyrins can be controlled by peripheral substitution and meso-aryl substituents.
An ether cleavage reaction of A2B-type subporphyrin bearing an ortho-anisyl substituent afforded a phenolate-bridged dimer. A head-to-tail structure of the dimer was unambiguously elucidated by single crystal X-ray diffraction analysis. UV-vis absorption and magnetic circular dichroism spectra indicated a minor interaction between the subporphyrin chromophores. Density functional theory calculations provided a detailed insight into the electronic structures of the subporphyrin dimer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.