Mononuclear ruthenium(II) and rhodium(III) complexes with S-[4-(2,2:6′,2″-terpyridin-4′-yl)phenoxy]butyl ethanethioate and 4′-[4-(1,2-dithiolane-3-yl)butylcarboxy)phenyl]-2,2′:6′,2″-terpyridine: Synthesis, electrochemistry, antibacterial activity and catalytical application

Synthesis, Characterization, and Biological Activity of New 4'-Functionalized Bis-Terpyridine Ruthenium(II) Complexes: Anti-Inflammatory Activity Advances

Ruthenium complexes incorporating 2,2' : 6',2''-terpyridine ligands have emerged as promising candidates due to their versatile biological activities including DNA-binding, anti-inflammatory, antimicrobial, and anticancer properties. In this study, three new 4'-functionalized bis(terpyridine) Ru(II) complexes were synthesized. These complexes feature one ligand as 4-(2,2' : 6',2''-terpyridine-4'-yl) benzoic acid and the second ligand as either 4'-(2-thienyl)-2,2' : 6',2''-terpyridine, 4'-(3,4-dimethoxyphenyl)-2,2' : 6',2''-terpyridine, or 4'-(4-dimethylaminophenyl)-2,2' : 6',2''-terpyridine. Besides the chemical characterization by 1H and 13C NMR, mass spectrometry, and absorption and emission spectroscopy, the complexes were tested for their biological activity as anti-inflammatory, anticancer, and antimicrobial agents. Moreover, the toxicity of the Ru(II) complexes was assessed and benchmarked against diclofenac potassium and ibuprofen using a haemolysis assay. Biological evaluations demonstrate that these ruthenium complexes exhibit promising therapeutic potential with reduced haemolytic activity compared to standard drugs. They demonstrate substantial anti-inflammatory effects through inhibition of albumin denaturation along with moderate cytotoxicity against cancer cell lines and broad-spectrum antimicrobial activity. These findings highlight the multifaceted biomedical applications of 4'-functionalized bis(terpyridine) Ru(II) complexes, suggesting their potential for further development as effective and safe therapeutic agents.

Recent developments in the synthesis and applications of terpyridine-based metal complexes: a systematic review

Terpyridine-based metal complexes have emerged as versatile and indispensable building blocks in the realm of modern chemistry, offering a plethora of applications spanning from materials science to catalysis and beyond. This comprehensive review article delves into the multifaceted world of terpyridine complexes, presenting an overview of their synthesis, structural diversity, and coordination chemistry principles. Focusing on their diverse functionalities, we explore their pivotal roles in catalysis, supramolecular chemistry, luminescent materials, and nanoscience. Furthermore, we highlight the burgeoning applications of terpyridine complexes in sustainable energy technologies, biomimetic systems, and medicinal chemistry, underscoring their remarkable adaptability to address pressing challenges in these fields. By elucidating the pivotal role of terpyridine complexes as versatile building blocks, this review provides valuable insights into their current state-of-the-art applications and future potential, thus inspiring continued innovation and exploration in this exciting area of research.

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.

"Chemistry-on-the-complex": functional RuII polypyridyl-type sensitizers as divergent building blocks

Ruthenium polypyridyl type complexes are potent photoactive compounds, and have found - among others - a broad range of important applications in the fields of biomedical diagnosis and phototherapy, energy conversion schemes such as dye-sensitized solar cells (DSSCs) and molecular assemblies for tailored photo-initiated processes. In this regard, the linkage of RuII polypyridyl-type complexes with specific functional moieties is highly desirable to enhance their inherent photophysical properties, e.g., with a targeting function to achieve cell selectivity, or with a dye or redox-active subunits for energy- and electron-transfer. However, the classical approach of performing ligand syntheses first and the formation of Ru complexes in the last steps imposes synthetic limitations with regard to tolerating functional groups or moieties as well as requiring lengthy convergent routes. Alternatively, the diversification of Ru complexes after coordination (termed "chemistry-on-the-complex") provides an elegant complementary approach. In addition to the Click chemistry concept, the rapidly developing synthesis and purification methodologies permit the preparation of Ru conjugates via amidation, alkylation and cross-coupling reactions. In this regard, recent developments in chromatography shifted the limits of purification, e.g., by using new commercialized surface-modified silica gels and automated instrumentation. This review provides detailed insights into applying the "chemistry-on-the-complex" concept, which is believed to stimulate the modular preparation of unpreceded molecular assemblies as well as functional materials based on Ru-based building blocks, including combinatorial approaches.

Ruthenium-Catalyzed Aerobic Oxidation of Amines

Amine oxidation is one of the fundamental reactions in organic synthesis as it leads to a variety of value-added products such as oximes, nitriles, imines, and amides among many others. These products comprise the key N-containing building blocks in the modern chemical industry, and such transformations, when achieved in the presence of molecular oxygen without using stoichiometric oxidants, are much preferred as they circumvent the production of unwanted wastes. In parallel, the versatility of ruthenium catalysts in various oxidative transformations is well-documented. Herein, this review focuses on aerobic oxidation of amines specifically by using ruthenium catalysts and highlights the major achievements in this direction and challenges that still need to be addressed.