Coordination-driven self-assembly of arene ruthenium metalla-rectangles

Altering the binding affinities of tetraruthenocycles for polycyclic aromatic hydrocarbons by post-assembly modification

We developed a strategy for manipulating the binding strength of polycyclic aromatic hydrocarbons (PAHs) via covalent post-assembly modification (PAM) of tetranuclear ruthenium macrocycles containing s-tetrazine ligands. The macrocycles act as efficient receptors for various PAHs. Inverse electron demand Diels-Alder (IEDDA) reaction of the macrocycles was applied to reduce the binding ability significantly.

Octametallic Cluster of Cp*Ir(glycinato) Cations

Removal of chloride from Cp*Ir(glycinato)Cl in noncoordinating solvents with Ag[PF₆] or Tl[PF₆] leads to the formation of a closed octametallic loop of cations. The same loop also sequesters a number of PF₆ ^- counter anions. This is in contrast with reports that piano-stool complexes with amino acids form only trimetallic [Cp*Ir(aminoacidato)]₃ ³⁺ moieties upon creating the cation. Cp*Ir(glycinato)Cl also forms a trimetallic compound as well as a octametallic compound, and the octametallic vs trimetallic formation appears to be dependent on the anion. The synthesis and characterization of the octametallic complex, as well as some monometallic and trimetallic compounds, are reported, including the X-ray crystal structures.

Coordination-Driven Self-Assembly of Triazole-Based Apoptosis-Inducible Metallomacrocycles

Ru(II)-metallomacrocycles containing 4-pyridyl-1,2,3-triazole moiety were realized by coordination-driven self-assembly. All new compounds were characterized by electrospray ionisation mass spectrometry, elemental analysis, and 1H and 13C NMR spectroscopic techniques. The molecular structure of metallomacrocycle 8 was determined by single-crystal X-ray crystallography. The anticancer activities of metallomacrocycles 5-8 were evaluated by cytotoxicity, cell cycle analysis, and related protein expression. Metallomacrocycle 7 showed the highest cytotoxicity in HepG2 human hepatocellular carcinoma cells. In addition, apoptotic HepG2 cells were analyzed when metallomacrocycle 7 was treated. Our results suggest that metallomacrocycle 7 induces liver cancer cell death by increasing apoptosis and cell cycle arrest and that it has potential use as an agent for the treatment of human hepatocellular carcinoma.

Investigation of the Anticancer Activity of Coordination-Driven Self-AssembledTwo-Dimensional Ruthenium Metalla-Rectangle

Coordination-driven self-assembly is an effective synthetic tool for the construction of spatially and electronically tunable supramolecular coordination complexes (SCCs), which are useful in various applications. Herein, we report the synthesis of a two-dimensional discrete metalla-rectangle [(η6-p-cymene)4Ru4(C6H2O4)2(2)2](CF3SO3)4 (3) by the reaction of a dinuclear half-sandwich ruthenium (II) complex [Ru2(η6-p-cymene)2(C6H2O4)Cl2] (1) and bis-pyridyl amide linker (2) in the presence of AgO3SCF3. This cationic ruthenium metalla-rectangle (3) has been isolated as its triflate salt and characterized by analytical techniques including elemental analysis, Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (1H-NMR), carbon nuclear magnetic resonance spectroscopy (13C-NMR), 1H-1H correlation spectroscopy (COSY), 1H-1H nuclear Overhauser effect spectroscopy (NOESY), diffusion ordered spectroscopy (DOSY), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). Significantly, the 2D cationic ruthenium metalla-rectangle showed better anticancer activity towards three different cell lines (A549, Caki-1 and Lovo) as compared with the parent ruthenium complex (1) and the commercially used drug, cisplatin.

Self-Assembled Multinuclear Complexes Incorporating 99m Tc

Multinuclear complexes or clusters are rarely investigated in medicinal inorganic chemistry although they represent structural intermediates between molecules and nanomaterials. We present in this report two strategies towards ^99m Tc-containing clusters. In a pre-assembly approach, the preformed but incomplete cluster fragment [Re₃ (μ₂ -OH)₃ (μ₃ -OH)(CO)₉ ]^- reacts with [^99m Tc(CO)₃ ]⁺ to the highly stable [^99m TcRe₃ (μ₃ -OH)₄ (CO)₁₂ ] cube. The same structure self-assembles when reacting the mononuclear Re and ^99m Tc precursors in one pot. Integrating the coordinating OH groups from Schiff bases in this concept leads straight to dinuclear, mixed-metal complexes of the type [^99m TcRe(μ₂ -O^N-R¹ )₂ (CO)₆ ] in quantitative yields. Both strategies are unprecedented and open a future path towards clusters, incorporating a ^99m Tc radiolabel while being decorated with targeting or cytotoxic moieties.