Electrochemical selenation in undivided electrochemical cells allows the preparation of selenium‐containing naphthoquinones. The rapid, green and efficient protocol avoids chemical oxidants and enables the synthesis of target molecules in a fast and reliable way. This strategy provides and efficient and general method for the synthesis of quinoidal compounds with activity against five cancer cell lines and Trypanosoma cruzi, the parasite that causes Chagas disease.

The present manuscript describes the synthesis of two novel 2,1,3-benzothiadiazole (BTD) derivatives containing an excited state intramolecular proton transfer (ESIPT) site. Photophysical properties, X-ray analysis, ESIPT and intramolecular charge-transfer (ICT) of these novel fluorescent monosubstituted BTD derivatives were investigated. It is also shown that ESIPT and ICT can take place concomitantly. Theoretical calculations (ab initio and DFT) corroborate the high stability of these derivatives in the excited state due to efficient ESIPT and ICT processes. Also, the optimized calculated geometries of these new structures allowed a better understanding of the different behaviour of the dyes in a wide pH range (1–13). Finally, the new compounds exhibit impressive cellular selectivity and stain only mitochondria in different cell lines and are far better than the commercially available MitoTracker-red.

Two novel coordination polymers (CPs) have been synthesized, characterized and successfully applied as robust heterogeneous catalysts for the Biginelli multicomponent reaction to obtain 3,4-dihydropyrimidin-2(1H)-one or thione (DHPMs) derivatives. The reaction was initially developed using both CPs and the Zn-based material showed much better catalytic activity. After the reaction optimization under batch conditions, a continuous flow protocol was developed and applied with impressive results. Four bioactive DHPMs were successfully synthesized with high yields. The mechanism of the transformation was also investigated by electrospray (tandem) mass spectrometry (ESI-MS(/MS)) analyses. Online monitoring of the reaction indicated under the developed conditions that the iminium mechanism is preferred over the enamine- and Knoevenagel-based mechanisms. Nine DHPMs had their antitumoral activities evaluated against MCF-7 (human breast cancer cells), A549 (human alveolar basal epithelial cells) and Caco-2 (human epithelial colorectal cells) cancer cell lineages. Fibroblasts (healthy cells) were not affected by the tested DHPMs showing an excellent selectivity for tumour cells. Three DHPMs returned impressive results, being capable of inhibiting tumour cell proliferation in 72 h.

Quinonoid compounds based on 5-iodo-1,4-disubstituted-, 1,4- and 1,5-disubstituted-1,2,3-triazoles were synthesized using simple methodologies and evaluated against T. cruzi, the etiological agent of Chagas disease, and cancer cell lines PC3, HCT-116, HL-60, MDA-MB-435 and SF-295. The cytotoxic potential of the lapachones was also assayed against peripheral blood mononuclear cells (PBMC). Two compounds 6 and 12 were identified as potential hits against T. cruzi. β-Lapachone-based 1,5-disubstituted-1,2,3-triazole (12) displayed an IC₅₀/24 h = 125.1 μM, similar to benznidazole, the standard drug. Compound 12 was also more active than the precursor β-lapachone against the cancer cell lines. These compounds acting as multitarget quinoidal systems could provide promising new leads for the development of trypanocidal and/or anticancer drugs.