Synthesis of Para-Acetylated Functionalized Ni(II)-POCOP Pincer Complexes and Their Cytotoxicity Evaluation Against Human Cancer Cell Lines

A series of three Ni(II)-POCOP complexes para-functionalized with an acetoxyl fragment were synthesized. All complexes (2 a-c) were fully characterized through standard analytical techniques. The molecular structure of complex 2 b was unambiguously determined by single-crystal X-ray diffraction, revealing that the metal center is situated in a slightly distorted square-planar environment. Additionally, the acetoxy fragment at the para-position of the phenyl ring was found to be present. The in vitro cytotoxic activity of all complexes was assessed on six human cancer cell lines. Notably, complex 2 b exhibited selective activity against K-562 (chronic myelogenous leukemia) and MCF-7 (mammary adenocarcinoma) with IC50 values of 7.32±0.60 μM and 14.36±0.02 μM, respectively. Furthermore, this compound showed negligible activity on the healthy cell line COS-7, highlighting the potential therapeutic application of 2 b. The cytotoxic evaluations were further complemented with molecular docking calculations to explore the potential biological targets of complex 2 b, revealing interactions with cluster differentiation protein 1a (CD1 A, PDB: 1xz0) for K-562 and with the progesterone receptor for MCF-7.

Dithiolato-Bridged Nickel(II) Salicylcysteamine Complexes as Robust Proton Reduction Electrocatalysts: Cyclic Voltammetry and Computational Studies

A series of Schiff-base nickel(II) complexes were prepared from the reaction of nickel(II) acetate with N-salicylcysteamine [HO-C₆H₄-CH═N(CH₂)₂SH] ligands. These complexes were analyzed to be dimeric nickel complexes containing two bridging thiolato ligands. Using cyclic voltammetry, they were found to be efficient homogeneous proton reduction electrocatalysts when acetic acid was used as the proton source in acetonitrile. Catalysis was triggered upon electrochemical reduction of the nickel complex. In particular, rate constants (k_obs) in the range of 10⁴ s^-1 at moderate overpotentials of 0.5-0.6 V were achieved when chloro- or bromo-containing nickel complexes were used. Combined with the experimental data, density functional theory calculations lent support to an ECEC mechanism, with the first electrochemical reduction step contributing significantly to the rate-determining step.

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.