Bismuth Complexes of Porphyrins and their Potential in Medical Applications

Abstract

In the past, the major medical application of bismuth consisted of the treatment of gastric ulcers by ingestion of large quantities of bismuth citrate. More recently, the resurgence of interest for bismuth medical applications has been more oriented towards possible applications in radiotherapy, and particularly in alpha-radioimmunotherapy (Figure 9.1) [1]. As this specific application will be reviewed exhaustively in Chapter 13 of this book, we will only discuss the design, synthesis and coordination properties of bismuth porphyrin complexes in this chapter, assuming that the goals and limits of this peculiar application are known. However, we should keep in mind that both alpha-emitter isotopes of bismuth-212 and 213 exhibit a very short half life of 60 and 45 min respectively, as this radiochemical property directly implies fast kinetics formation of complexes. Even if this potential application is far from being achieved, this very basic requirement will guide the research for new bismuth porphyrins.From the coordination point of view, porphyrins are known to coordinate most of the metallic and pseudometallic elements, and metalloporphyrins with over 80 different central

Amino Acid–Porphyrin Conjugates: Synthesis and Study of their Photophysical and Metal Ion Recognition Properties

“…Porphyrins are macrocyclic molecular systems with a ring‐shaped tetrapyrrolic core. These systems are important in various biological processes and are capable of forming complexes with a variety of metal ions . For example, heme is an iron chelate of a porphyrin, whereas chlorophyll and bacteriochlorophyll are the magnesium chelates.…”

A Pentanuclear Lead(II) Complex Based on a Strapped Porphyrin with Three Different Coordination Modes

“…Coordination chemistry of either bismuth(III) or lead(II) cations remains largely unexplored in porphyrin platform-based ligands. , As a result, structural data available are limited to a few examples . However, because they possess a stereochemically active 6s 2 lone pair, both of these elements are expected to exhibit some similarities in their coordination properties. , For a decade now, our group has been investigating the influence of various types of functionalities such as pendant pickets or crown-ethers around the coordination site of the macrocycle on its coordination properties .…”

Synthesis, Spectral, and Electrochemical Characterization of the First Arsenic(V)-Phthalocyanines

“…Nowadays, derivatives of phosphorus(V), arsenic(III), and antimony(III), as well as bismuth(III) and antimony(V) ,,,− are known, but they are still uncommon. This is rather surprising because porphyrin analogues, which have a similar tetra-pyrrole molecular skeleton, have been relatively well studied . In particular, no arsenic(V)-Pc is known despite that arsenic(III)-Pcs are known and antimony(III)-Pcs can readily be converted to the corresponding antimony(V)-Pcs. ,,− This is not only because of poor solubility of the known arsenic(III)-complexes ligating the pc ligand (pc denotes unsubstituted phthalocyaninate, C 32 H 16 N 8 2– ) in common organic solvents but also provably because of their instability exemplified in this work and of the toxicity of arsenic .…”