Rhenium(I)-tricarbonyl complexes with methimazole and its selenium analogue: Syntheses, characterization and cell toxicity.

This study explores the effect of a thione/selone ligand on the cell toxicity (in vitro) and light activity of diimine Re(CO)3+ complexes. Six rhenium(I) complexes with general formula fac-[Re(CO)3(N,N')X]+ were prepared, where X = 2-mercapto-1-methylimidazole (methimazole; MMI), and 1-methylimidazole-2-selone (MSeI); N,N' = 2,2'-bipyridine (bpy), 1,10-phenanthroline (phen) and 2,9-dimethyl-1,10-phenanthroline (dmphen). Their triflate salts were characterized using single-crystal X-ray diffraction, 1H, 13C and 2D NMR, UV-vis and vibrational spectroscopy. Their cytotoxic properties were tested, showing significant cytotoxicity (IC50 = 8.0-55 µM) towards the human breast cancer cell line MDA-MB-231. The half-inhibitory concentration (IC50) for fac-[Re(CO)3(dmphen)(MMI)]+, the most toxic complex in this series (8.0 ± 0.2 µM), was comparable to that of the corresponding aqua complex fac-[Re(CO)3(dmphen)(H2O)]+ with IC50 = 6.0 ± 0.1 µM. The fac-[Re(CO)3(bpy)(MMI/MSeI)]+ complexes were somewhat less toxic towards the human embryonic kidney cell line HEK-293 T after 48 h of exposure. The stability of the complexes upon irradiation was monitored using UV-vis spectroscopy, with no CO released when exposed to UV-A light (λ = 365 nm).

Microporous Metal-Phosphonates with a Novel Orthogonalized Linker and Complementary Guests: Insights for Trivalent Metal Complexes from Divalent Metal Complexes.

The reliable self-assembly of microporous metal-phosphonate materials remains a longstanding challenge. This stems from, generally, more coordination modes for the functional group allowing more dense structures, and stronger bonding driving less crystalline products. Here, a novel orthogonalized aryl-phosphonate linker, 1,3,5-tris(4'-phosphono-2',6'-dimethylphenyl) benzene (H6 L3) has been used to direct formation of open frameworks. The peripheral aryl rings of H6 L3 are orthogonalized relative to the central aromatic ring giving a tri-cleft conformation of the linker in which small aromatic molecules can readily associate. When coordinated to magnesium ions, a series of porous crystalline metal-organic, and hydrogen-bonded metal-organic frameworks (MOFs, HMOFs) are formed (CALF-41 (Mg), HCALF-42 (Mg), -43 (Mg)). While most metal-organic frameworks are tailored based on choice of metal and linker, here, the network structures are highly dependent on the inclusion and structure of the guest aromatic compounds. Larger guests, and a higher stoichiometry of metal, result in increased solvation of the metal ion, resulting in networks with connectivities increasingly involving hydrogen-bonds rather than direct phosphonate coordination. Upon thermal activation and aromatic template removal, the materials exhibit surface areas ranging from 400-600 m2 /g. Self-assembly in the absence of aromatic guests yields mixtures of phases, frequently co-producing a dense 3-fold interpenetrated structure (1). Interestingly, a series of both more porous (530-900 m2 /g), and more robust solids is formed by complexing with trivalent metal ions (Al, Ga, In) with aromatic guest; however, these are only attainable as microcrystalline powders. The polyprotic nature of phosphonate linkers enables structural analogy to the divalent analogues and these are identified as CALF-41 analogues. Finally, insights to the structural transformations during metal ion desolvation in this family are gained by considering a pair of structurally related Co materials, whose hydrogen-bonded (HCALF-44 (Co)) and desolvated (CALF-44 (Co)) coordination bonded networks were fully structurally characterized.

Porous coordination polymer with flexibility imparted by coordinatively changeable lithium ions on the pore surface.

Solvothermal reactions of equimolar zinc acetate, lithium acetate, and 1,3,5-benzenetricarboxylic acid (H(3)btc) in different mixed solvents yielded isostructural three-dimensional frameworks [LiZn(btc)(cG)].lG [cG and lG denote coordinated and lattice guests, respectively; cG = (nmp)(0.5)(H(2)O)(0.5), lG = (EtOH)(0.5) (1a); cG = H(2)O, lG = EtOH (1b); nmp = N-methyl-2-pyrrolidone] with one-dimensional channels occupied by guest molecules and solvent-coordinated, extrusive Li(+) ions. Thermogravimetry analyses and powder X-ray diffraction measurements revealed that both 1a and 1b can lose all lattice and coordinated guests to form a desolvated phase [LiZn(btc)] (MCF-27, 1) and almost retains the original framework structure. Gas adsorption measurements on 1 confirmed its permanent porosity but suggested a structural transformation from 1a/1b to 1. It is noteworthy that only 1a can undergo a single-crystal to single-crystal (SCSC) transformation into 1 upon desolvation. The crystal structure of 1 revealed that the Li(+) ions were retracted into the channel walls via complementary coordination to the carboxylate oxygen atoms in the framework rather than being exposed on the pore surface. Single-crystal X-ray diffraction analyses were also performed for N(2)- and CO(2)-loaded samples of 1, revealing that the framework remained unchanged when the gases were adsorbed. Although the gas molecules could not be modeled, the residue electrons inside the channels demonstrated that the retracted Li(+) ions still behave as the primary interacting site for CO(2) molecules. Nevertheless, solvent molecules such as H(2)O can readily compete with the framework oxygen atom to retrieve the extrusive Li(+) ions, accompanying the reverse structural transformation, i.e., from 1 to 1a/1b.