Syntheses and characterization of two novel cadmium(II) coordination polymers derived from pyridyl substituted terpyridine and diphenate mixed ligands

Influence of a series of pyridine ligands on the structure and photophysical properties of Cd(ii) complexes

Five Cd(ii) complexes based on α-acetamidocinnamic acid (HACA) and a set of N,N^N and N^N^N-pyridine (dPy) yield complexes with diverse nuclearities and enhanced quantum yields, benefiting from the chelation enhanced effect (CHEF) of dPy.

Isomers of Terpyridine as Ligands in Coordination Polymers and Networks Containing Zinc(II) and Cadmium(II)

The use of divergent 4,2′:6′,4″- and 3,2′:6′,3″-terpyridine ligands as linkers and/or nodes in extended coordination assemblies has gained in popularity over the last decade. However, there is also a range of coordination polymers which feature 2,2′:6′,2″-terpyridine metal-binding domains. Of the remaining 45 isomers of terpyridine, few have been utilized in extended coordination arrays. Here, we provide an overview of coordination polymers and networks containing isomers of terpyridine and either zinc(II) and cadmium(II). Although the motivation for investigations of many of these systems is their luminescent behavior, we have chosen to focus mainly on structural details, and we assess to what extent assemblies are reproducible. We also consider cases where there is structural evidence for competitive product formation. A point that emerges is the lack of systematic investigations.

Platinum(II) coordination compounds with 4'-pyridyl functionalized 2,2':6',2″-terpyridines as an alternative to enhanced chemotherapy efficacy and reduced side-effects

Two platinum(II) coordination compounds, [PtCl(4'-R¹-terpy)](SO₃CF₃) (1) and [PtCl(4'-R²-terpy)](SO₃CF₃) (2), with 4'-(2-pyridyl)-2,2':6',2″-terpyridine (4'-R¹-terpy) or 4'-(3-pyridyl)-2,2':6',2″-terpyridine (4'-R²-terpy) were synthesized and the impact of the pendant pyridyl ring on the structure and cytotoxic activity of Pt(II)-terpyridine complexes was explored. The single-crystal X-ray diffraction analysis confirmed square planar coordination of the cations [PtCl(4'-Rⁿ-terpy)]⁺. The mode of binding of 1 and 2 to calf thymus DNA was examined by UV-Vis absorption titration, ethidium displacement assay and reaction with 9-ethylguanine, and the mixed covalent-intercalative mode was demonstrated. The cytotoxicity of the Pt(II) complexes against six cancer cell lines and three normal ones was determined using MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay and compared to cisplatin. The IC₅₀ values for the compound 2 towards the cancer cell lines are in the low micromolar range. Most remarkably, 2 was over 4 times more effective than 1 and cisplatin against non-small lung adenocarcinoma (A549), and its selectivity index was ~60-80 times higher than that for 1 and cisplatin. The mechanisms underlying the loss of viability under treatment of 2 was further investigated including F-actin staining, mitotic index analysis, cytometric cell cycle analysis, Fluorescein isothiocyanate (FITC) -conjugated Annexin V antibody and propidium iodide (PI) staining, measurements of reactive oxygen species (ROS) in cells, analysis of changes in the mitochondrial mass and potential and quantitative real time polymerase chain reaction (qRT-PCR) genes analysis. The compound 2 was found to have a pro-oxidative effect by strong stimulation of cells for the production of reactive oxygen species and cytostatic effect through cell cycle arrest.

Cytotoxic gold(iii) complexes incorporating a 2,2′:6′,2′′-terpyridine ligand framework – the impact of the substituent in the 4′-position of a terpy ring

The possibility of tuning the cytotoxic activity of Au(iii) complexes by structural modifications of a terpy ligand has been examined.

A novel single-site manganese(II) complex of a pyridine derivative as a catalase mimetic for disproportionation of H2O2 in water

A novel single site Mn(II) complex was successfully synthesized and tested in the aqueous disproportionation of hydrogen peroxide. The complex was found to be stable (HR-XAS) and exhibits catalase-like activity in neutral pH. Theoretical calculations suggested a reaction mechanism involving two complexes, changes in metal oxidation state and proton shuttling.