The growing worldwide cancer incidence, coupled to the increasing occurrence of multidrug cancer resistance, requires a continuous effort towards the identification of new leads for cancer management. In this work, two C-scorpionate complexes, [FeCl2(κ3-Tpm)] (1) and [Co(κ3-TpmOH)2] (2), (Tpm = hydrotris(pyrazol-1-yl)methane and TpmOH = 2,2,2-tris(pyrazol-1-yl)ethanol), are studied as potential scaffolds for future anti-cancer drug development. Their cytotoxicity and cell migration inhibitory activity are analyzed, and an untargeted metabolomics approach is em-ployed to elucidate the biological processes significantly affected by these two complexes, using two tumoral cell lines (B16 and HCT116) and a non-tumoral cell line (HaCaT). While [FeCl2(κ3-Tpm)] did not display a significant cytotoxicity, [Co(κ3-TpmOH)2] was particularly cy-totoxic against the B16 cell line. While [Co(κ3-TpmOH)2] significantly inhibited cell migration in all tested cell lines, [FeCl2(κ3-Tpm)] displayed a mixed activity. From a metabolomics perspective, exposure to [FeCl2(κ3-Tpm)] is associated with changes in various metabolic pathways involving tyrosine, where iron-dependent enzymes are particularly relevant. On the other hand, [Co(κ3-TpmOH)2] is associated with dysregulation of cell adhesion and membrane structural pathways, suggesting its antiproliferative and anti-migration properties can be due to changes in the overall cellular adhesion mechanisms.

Complexes of triply positive europium ion with organic ligands are popular objects for studying photophysical properties. This is related not only to the bright red emission of this 4f element, but also to some spectroscopic peculiarities of its luminescence: the first excited spin-orbit level (7F1) lies only about 300 cm−1 above the ground state (7F0), so that at room temperature its population is around 25–30%. However, such electronic structure of Eu(III) provides its paramagnetism under ordinary conditions. This fact is often ignored by researchers, which is shortsighted from the materials science point of view. A comprehensive and systematic study of the magnetic behavior for the Eu(III) molecular coordination compounds is a challenging task for the development of new polyfunctional materials. The present work presents synthesis, single crystal XRD analysis results, and a magnetic study for the firstly prepared europium(III) complexes with two neutral scorpionate ligands: trispyrazolylmethane (HCPz3) and its methylated analog, tris(3,5-dimethyl-1-pyrazolyl)methane (HC(PzMe2)3). The values of the spin-orbit coupling parameter obtained for Eu-trication by a theoretical approximation of the experimental magnetic susceptibility data are compared with those known for the scarce amount of the magnetically studied molecular compounds.