Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Abstract

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Tetrelanes versus Tetrylenes as Precursors to Transition Metal Complexes Featuring Tridentate PEP Tetryl Ligands (E=Si, Ge, Sn)

“…These types of compounds are currently unknown despite the attachment of plumbylenes to transition metals [89,90] and even the formation of PPbP plumbylene complexes have been described [90] . In addition, regarding the applicability of PEP tetryl transition metal complexes, their successful participation in catalysis has already been demonstrated (many examples are mentioned in this review) and they might also present interesting medical/biological applications (yet to be investigated), which are currently being discovered for metal complexes supported by other pincer ligands [3a–c] …”

Dinuclear oxidovanadium complexes with dihydrazone ligands derived from diethyl 2,6-dimethylpyridine-3,5-dicarboxylate obtained from Hantzsch reaction; crystal structure and catalytic activity

“…Hydrazones are a class of flexible, strong and attractive nitrogen and oxygen donor ligands in coordination chemistry. 1 Due to the presence of N–N and NH–C(O)– units in the structure of these ligands, they usually act as tridentate ligands 2 and based on the different groups attached to the mentioned functional unit, they can form a wide variety of structures ranging from simple mononuclear complexes 3 to complicated clusters and coordination polymers. 4 Due to the presence of amide–iminol tautomerization, these ligands can stabilize metal ions in different oxidation states.…”

Novel Pyrazole‐Based Transition Metal Complexes: Spectral, Photophysical, Thermal and Biological Studies

“…[27] Schiff base have likewise been utilized for scientific purposes in the assurance of metal ions, and some Schiff base derivatives have been utilized in the extraction of metal solvents. [28] Different applications of such metal complexes depend generally on their molecular structures. [29] Schiff base ligands can coordinate to a wide range of metals and to stabilize them in different oxidation states.…”