Dinuclear arene ruthenium dichloro complexes designed for host–guest propensity

Modular synthesis of antimalarial quinoline-based PGM metallarectangles

A new ditopic, quinoline-based ligand L (7-chloro-4-(pyridin-4-yl)quinoline) was synthesized via a Suzuki cross-coupling reaction. The ligand was utilized to synthesize the corresponding half-sandwich iridium(III) and ruthenium(II) binuclear complexes (1c and 1d) and the subsequent metallarectangles (2c, 2d, 3c, and 3d), via [2 + 2] coordination-driven self-assembly. Single-crystal X-ray diffraction confirmed the proposed molecular structure of the binuclear complex [{IrCl₂(Cp*)}₂(μ-L)] (1c) and DFT calculations were used to predict the optimized geometry of the rectangular nature of [{Ir(μ-Cl)(Cp*)}₄(μ-L)₂](CF₃SO₃)₄ (2c). All of the metallarectangles were isolated as their triflate salts and characterized using various spectroscopic (¹H, ¹³C{¹H}, DOSY NMR, and IR spectroscopy) and analytical techniques (ESI-MS). The synthesized compounds were screened against the NF54 chloroquine-sensitive (CQS) and K1 chloroquine-resistant (CQR) strains of Plasmodium falciparum. Incorporation of the ubiquitous quinoline core and metal complexation significantly enhanced the in vitro biological activity, with an increase in the nuclearity correlating with an increase in the resultant antiplasmodial activity. This was observed across both parasitic strains, alluding to the potential of supramolecular metallarectangles to act as antiplasmodial agents. Inhibition of haemozoin formation was considered a potential mechanism of action and selected metallarectangles exhibit β-haematin inhibition activity with near comparable activity to chloroquine.

4-Cyanopyridine complexes [MX2(4-CNpy)x]n (with X = Cl, Br and x = 1, 2): crystal structures, thermal properties and a comparison with [MX2(3-CNpy)x]n complexes

Crystal structures of [MX₂(4-CNpy)_x] with X = Cl and Br, M = Mn, Fe, Co, Ni, Cu, and Zn, and x = 1 and 2 were determined by X-ray powder diffraction. 4-Cyanopyridine can build chain and net structures.

Coordination compounds built up from MIICl2 and 3-cyanopyridine: double chains, single chains and isolated complexes

Crystal structures of [M^IICl₂(3-CNpy)_x], with M = Mn, Fe, Co, Ni, Cu, Zn and x = 1, 2, were determined by X-ray powder diffraction. Surprisingly, 3-cyanopyridine coordinates monodentately only.

Impacts of the counter ions on 4,5-dicyano-1-methylimidazole silver coordination

The counter ion regulates the coordination in silver dicyanoimidazole derivatives.

3-Cyanopyridine as a bridging and terminal ligand in coordination polymers

Crystal structures of [M^IIBr₂(3-CNpy)_x]_(n) with M = Mn, Fe, Co, Ni and x = 1, 2, 4 were determined by powder diffraction. For x = 1, the 3-cyanopyridine ligand is bridging two metal atoms.

4-Cyanopyridine, a versatile mono- and bidentate ligand. Crystal structures of related coordination polymers determined by X-ray powder diffraction

4-Cyanopyridine (4-CNpy) as a monodentate ligand in single or double chains or as a bidentate ligand in two-dimensional networks.

Organometallic chemistry meets crystal engineering to give responsive crystalline materials

Dynamically porous crystalline materials have been obtained by engineering organometallic molecules. This feature article deals with organometallic wheel-and-axle compounds, molecules with two relatively bulky groups (wheels) connected by a linear spacer. The wheels are represented by half-sandwich Ru(ii) moieties, while the spacer can be covalent or supramolecular in character. Covalent spacers are obtained using divergent bidentate ligands connecting two [(arene)RuX2] groups. Supramolecular spacers are instead obtained by exploiting the dimerization of COOH or C(O)NH2 groups appended to N-based ligands. A careful choice of ligand functional groups and X ligands leads to the isolation of crystalline materials with remarkable host-guest properties, evidenced by the possibility of reversibly capturing/releasing volatile guests through heterogenous solid-gas reactions. Structural correlations between the crystalline arrangement of the apohost and the host-guest compounds allow us to envisage the structural path followed by the system during the exchange processes.