meso-Diketopyripentaphyrin and Diketopyrihexaphyrin as Macrocyclic Tripyrrinone Ligands for NiII Ions

We report expanded porphyrins with pyridine rings and two neighboring carbonyl groups, which allow Ni^II ions to coordinate to the tripyrrinone-type NNNO coordination structure with Ni-O bonds. The selectivity of tripyrrinone is superior to other pyrrolic or pyridinic cavities of expanded porphyrins. Introduction of α-carbonyl pyridine next to the tripyrrolic conjugated structure is a powerful strategy for regioselective metalation of flexible expanded porphyrinoids.

Synthesis of 5,10-bis(Trifluoromethyl) Substituted β-Octamethylporphyrins and Central-Metal-Dependent Solvolysis of Their meso-Trifluoromethyl Groups

5,10-Bistrifluoromethyl substituted β-octamethylporphyrins were synthesized via a scrambling side reaction of a dipyrromethane precursor in the presence of a large excess of trifluoroacetic acid. Compared with the trans-analogs, the cis-analogs of meso-trifluoromethyl β-octaalkylporphyrin showed more red-shifted absorption bands. These meso-trifluoromethyl derivatives of β-octaalkylporphyrins underwent smooth metalation, similar to other common porphyrins, however, the corresponding zinc complexes underwent a type of solvolysis, whereby the trifluoromethyl groups were converted into methoxycarbonyl groups by the methanol used as solvent. UV-visible absorption spectra and X-ray crystal structure analyses revealed that the presence of a methoxycarbonyl substituent did not influence the deformation of the molecular framework and its absorption properties; this is because the methoxycarbonyl has a planar and perpendicular geometry, as opposed to the relatively bulky trifluoromethyl substituent.

Crystal structure of [5-n-butyl-10-(2,5-di-meth-oxy-phen-yl)-2,3,7,8,13,12,17,18-octa-ethyl-porphyrin-ato]nickel(II)

The asymmetric unit of the title nickel(II) porphyrin, [Ni(C48H60N4O2)], contains one independent mol-ecule. The average Ni-N bond length is 1.917 (13) Å. The mol-ecules are arranged in a closely spaced lattice structure in which neighbouring porphyrins are oriented in inversion-related dimers. The nickel(II) porphyrin is characterized by a significant degree of a ruffled (B 1u ) conformation with small contributions from saddle (B 2u ) and wave (y) [Eg (y)], as determined using normal structural decomposition. Disorder in the 2,5-di--meth-oxy-phenyl substituent was modelled over two positions with a 60% occupancy for the major moiety. One of the ethyl groups is also disordered over two positions and was modelled with the major moiety being present in 51.3% occupancy.