Formation of Stable NiIII N-Confused Porphyrins Aided by a 3-Ethoxy Group.

We report the synthesis, characterization, and reactivities of two stable NiIII N-confused porphyrin (NCP) complexes. Metalation of 3-OEt NCP 1 with NiCl2 ⋅ 6H2 O in CHCl3 /EtOH gave 3-OEt NiII NCP 3 initially, which was easily oxidized in air to form the NiIII complex of NCP inner C-oxide 4. Bis-ethoxy-modified NiIII complex 5 was synthesized by oxidation of 3 with PIFA in ethanol and CHCl3 . The structures of 4 and 5 were determined by single-crystal X-ray diffraction analysis. An unusually long NiIII -C bond (2.170(9) Å) was observed in 4. The g-factor (g>2.1) observed in the EPR spectra of 4 and 5 further confirmed that they are paramagnetic NiIII complexes. Comparative experiments showed that the 3-ethoxy group plays an important role in the formation of 4 and 5. Reduction of 4 and 5 with NaBH4 regenerated complex 3.

Porphyrin nanotubes based on a hydrogen-bonded organic framework.

Tubular structures offer a wide variety of applications; therefore, designing such materials with distinct dimensions is highly desirable yet challenging. In the current report, we have demonstrated the synthesis of a one-dimensional (1D) tubular assembly comprising porphyrin nanoring subunits. The porphyrin nanoring (PNR) 2 bearing ester groups was synthesized via Pt-mediated cyclization and then hydrolyzed to obtain PNR 3 with carboxylic groups. Under optimized conditions, porphyrin nanotubes (PNTs) were formed through hydrogen bonding between the carboxylic groups of 3. The morphology investigated by both SEM and TEM displayed well-defined arrays of nanotube bundles up to several micrometers long. Small crystals of PNTs were obtained by heating a solution of 3 in DMSO. High-resolution transmission electron microscopy (HR-TEM) accompanied by selected-area electron diffraction (SAED) exhibited a line of diffractions with d-spacing values of 6.17, 3.08, 2.07, and 1.57 Å. The miller indices of these diffractions could be assigned as 300, 600, 900, and 1200, respectively, suggesting that an ordered structure of 1D PNTs has been formed.