The anticancer, antimicrobial and antiplasmodial activities of six gold(iii) bis(dithiolene) complexes were studied. Complexes 1–6 showed relevant anticancer properties against A2780/A2780cisR ovarian cancer cells (IC50 values of 0.08–2 μM), also being able to overcome cisplatin resistance in A2780cisR cells. Complex 1 also exhibited significant antimicrobial activity against Staphylococcus aureus (minimum inhibitory concentration (MIC) values of 12.1 ± 3.9 μg mL−1) and both Candida glabrata and Candida albicans (MICs of 9.7 ± 2.7 and 19.9 ± 2.4 μg mL−1, respectively). In addition, all complexes displayed antiplasmodial activity against the Plasmodium berghei parasite liver stages, even exhibiting better results than the ones obtained using primaquine, an anti-malarial drug. Mechanistic studies support the idea that thioredoxin reductase, but not DNA, is a possible target of these complexes. Complex 1 is stable under biological conditions, which would be important if this compound is ever to be considered as a drug. Overall, the results obtained evidenced the promising biological activity of complex 1, which might have potential as a novel anticancer, antimicrobial and antiplasmodial agent to be used as an alternative to current therapeutics.

A new compound, [Fe(5–Cl-qsal)₂][Ni(α-tpdt)₂].CH₃CN, where α-tpdt = 2,3-thiophenedithiolate and H5–Cl-qsal = N-(8-quinolyl)-5-chlorosalicylaldimine, was prepared and structurally and magnetically characterized. The crystal structure is based on an arrangement of alternate layers of [Fe(5–Cl-qsal)₂]⁺ cations and [Ni(α-tpdt)₂]⁻ anions. The magnetic measurements and Mössbauer spectroscopy revealed hybrid behavior in this compound, where a ferromagnetic cluster-glass behavior, ascribed to the anions network, and a spin crossover (SCO) of the [Fe(5–Cl-qsal)₂]⁺ cations were observed. The glassy behavior, with a blocking temperature of ca. 7.5 K, results from the disorder in the anionic layer and the competition between ferro- and antiferromagnetic interactions in the anionic layers. The SCO process with T_1/2 = 298 K (high spin fraction = γ_HS = 0.5) is rather sluggish in the limits of the conversion (γ_HS ∼ 0 and γ_HS ∼ 1), which is attributed to the effect of the anions that seem to restrict somehow the structural distortions of the cations associated with the SCO process.