Novel Re(I) Complexes as Potential Selective Theranostic Agents in Cancer Cells and In Vivo in Caenorhabditis elegans Tumoral Strains.

A series of rhenium(I) complexes of the type fac-[Re(CO)3(N^N)L]0/+, Re1-Re9, was synthesized, where N^N = benzimidazole-derived bidentate ligand with an ester functionality and L = chloride or pyridine-type ligand. The new compounds demonstrated potent activity toward ovarian A2780 cancer cells. The most active complexes, Re7-Re9, incorporating 4-NMe2py, exhibited remarkable activity in 3D HeLa spheroids. The emission in the red region of Re9, which contains an electron-deficient benzothiazole moiety, allowed its operability as a bioimaging tool for in vitro and in vivo visualization. Re9 effectivity was tested in two different C. elegans tumoral strains, JK1466 and MT2124, to broaden the oncogenic pathways studied. The results showed that Re9 was able to reduce the tumor growth in both strains by increasing the ROS production inside the cells. Moreover, the selectivity of the compound toward cancerous cells was remarkable as it did not affect neither the development nor the progeny of the nematodes.

Encapsulation of Phosphorescent Pt(II) Complexes in Zn-Based Metal-Organic Frameworks toward Oxygen-Sensing Porous Materials.

In this work, we synthesized two tailored phosphorescent Pt(II) complexes bearing a cyclometalating tridentate thiazole-based C^N*N pincer luminophore (L) and exchangeable chlorido ([PtCl(L)]) or cyanido ([PtCN(L)]) coligands. While both complexes showed photoluminescence from metal-perturbed ligand-centered triplet states (3MP-LC), [PtCN(L)] reached the highest phosphorescence quantum yields and displayed a significant sensitivity toward quenching by 3O2. We encapsulated them into two Zn-based metal-organic frameworks, namely, MOF-5 and ZIF-8. The incorporation of the organometallic compounds in the resulting composites [PtCl(L)]@ZIF-8, [PtCN(L)]@ZIF-8, [PtCl(L)]@MOF-5, and [PtCN(L)]@MOF-5 was verified by powder X-ray diffractometry, scanning electron microscopy, time-resolved photoluminescence spectroscopy and microscopy, as well as N2- and Ar-gas sorption studies. The amount of encapsulated complex was determined by graphite furnace atomic absorption spectroscopy, showing a maximum loading of 3.7 wt %. If compared with their solid state forms, the solid-solution composites showed prolonged 3O2-sensitive excited state lifetimes for the complexes at room temperature, reaching up to 18.4 µs under an Ar atmosphere, which is comparable with the behavior of the complex in liquid solutions or even frozen glassy matrices at 77 K.