Rhenium(I) tricarbonyl complex of 5,20-bis(p-tolyl)-10,15-bis(p-methoxyphenyl)-21-selenaporphyrin: first X-ray structural characterization of metal complex of 21-selenaporphyrin

Metal Complexes of Porphyrinoids Containing Nonpyrrolic Heterocycles

The replacement of one or more pyrrolic building block(s) of a porphyrin by a nonpyrrolic heterocycle leads to the formation of so-called pyrrole-modified porphyrins (PMPs), porphyrinoids of broad structural variability. The wide range of coordination environments (type, number, charge, and architecture of the donor atoms) that the pyrrole-modified frameworks provide to the central metal ions, the frequent presence of donor atoms at their periphery, and their often observed nonplanarity or conformational flexibility distinguish the complexes of the PMPs clearly from those of the traditional square-planar, dianionic, N₄-coordinating (hydro)porphyrins. Their different coordination properties suggest their utilization in areas beyond which regular metalloporphyrins are suitable. Following a general introduction to the synthetic methodologies available to generate pyrrole-modified porphyrins, their general structure, history, coordination chemistry, and optical properties, this Review highlights the chemical, electronic (optical), and structural differences of specific classes of metalloporphyrinoids containing nonpyrrolic heterocycles. The focus is on macrocycles with similar "tetrapyrrolic" architectures as porphyrins, thusly excluding the majority of expanded porphyrins. We highlight the relevance and application of these metal complexes in biological and technical fields as chemosensors, catalysts, photochemotherapeutics, or imaging agents. This Review provides an introduction to the field of metallo-PMPs as well as a comprehensive snapshot of the current state of the art of their synthesis, structures, and properties. It also aims to provide encouragement for the further study of these intriguing and structurally versatile metalloporphyrinoids.

Rhenium in the core of porphyrin and rhenium bound to the periphery of porphyrin: synthesis and applications

An overview of most of the well known rhenium porphyrins (rhenium in the core of porphyrins) is presented here reviewing their synthesis, coordination chemistry, and applications. The important features of oxorhenium(v) porphyrins are discussed elaborately taking into account their application in epoxidation reaction. Moreover, the chemistry of some recently known porphyrin-Re conjugates (rhenium bound to the periphery of porphyrin) is reported considering their applications in the photochemical carbon dioxide reduction process and photodynamic therapy. The number of well characterized rhenium porphyrinoids are limited but they show interesting diverse properties, some of which are also discussed in this review.