Evaluation of structurally related acyclic ligands OBETA, EHDTA, and EGTA for stable Mn complex formation.

In recent years, significant research efforts have been dedicated to finding efficient and safe alternatives to the currently used gadolinium (Gd)-based MRI contrast agents. Among the most explored alternatives are paramagnetic chelates of the Earth-abundant Mn, which form a prominent class of metal complexes. The design of Mn complexes with enhanced relaxation properties and improved safety profiles hinges on a delicate balance between thermodynamic and kinetic stability, as well as the presence of coordinated water molecules.

Comprehensive Investigation of [Fe(EDTA)]-Functionalized Derivatives and their Supramolecular Adducts with Human Serum Albumin.

In recent years, the coordination chemistry of high-spin Fe(III) complexes has increasingly attracted interest due to their potential as effective alternatives to Gd(III)-based MRI contrast agents. This paper discusses the results from our study on Fe(III) complexes with two EDTA derivatives, each modified with either one (EDTA-BOM) or two (EDTA-BOM) benzyloxymethylene (BOM) groups on the acetic arm(s). These pendant hydrophobic groups enable the complexes to form noncovalent adducts with human serum albumin (HSA), leading to an observed increase in relaxivity due to the reduction in molecular tumbling.

Improving the In Vivo Stability of [Mn]Mn(II) Complexes with 18-Membered Macrocyclic Chelators for PET Imaging.

We report the [Mn/Mn]Mn(II) complexes of the macrocyclic chelators PYAN [3,6,10,13-tetraaza-1,8(2,6)-dipyridinacyclotetradecaphane] and CHXPYAN [(4,4,10,10)-3,5,9,11-tetraaza-1,7(2,6)-dipyridina-4,10(1,2)-dicyclohexanacyclododecaphane]. The X-ray crystal structures of Mn-PYAN and Mn-CHXPYAN evidence distorted octahedral geometries through coordination of the nitrogen atoms of the macrocycles. Cyclic voltammetry studies evidence reversible processes due to the Mn(II)/Mn(III) pair, indicating that the complexes are resistant to oxidation.

TRASUTA: The Effect of the Structural Rigidity of a Mesocyclic AAZTA-like Chelating Agent on the Thermodynamic, Kinetic, and Structural Properties of Some Divalent Metal and Ga Complexes.

Mesocyclic chelating agents such as AAZTA and its derivatives have been recently reported to overcome the relatively low thermodynamic stability of metal complexes of acyclic chelating agents and the slow complexation kinetics of macrocyclic chelating agents. This work reports the preparation of a spirobicyclic hexadentate AAZTA-like chelating agent (TRASUTA) and the investigation of the thermodynamic, kinetic, and structural properties of the corresponding chelates with the PET-relevant Ga and selected metal ions. A combination of analytical techniques allowed identification of a coordination isomerization process, involving the coordinating side arms and the inversion of a nitrogen atom and leading to lower thermodynamic and kinetic inertness with respect to mononuclear mesocyclic analogues.

New Salicylanilide Derivatives and Their Peptide Conjugates as Anticancer Compounds: Synthesis, Characterization, and Effect on Glioblastoma.

Pharmacologically active salicylanilides (2-hydroxy--phenylbenzamides) have been a promising area of interest in medicinal chemistry-related research for quite some time. This group of compounds has shown a wide spectrum of biological activities, including but not limited to anticancer effects. In this study, substituted salicylanilides were chosen to evaluate the activity on U87 human glioblastoma (GBM) cells.