Cell viability imaging in tumor spheroids DNA binding of a ruthenium(II) light-switch complex.

The famous ''light-switch'' ruthenium complex [Ru(bpy)(dppz)](PF) (1) has been long known for its DNA binding properties . However, the biological utility of this compound has been hampered by its poor cellular uptake in living cells. Here we report a bioimaging application of 1 as cell viability probe in both 2D cells monolayer and 3D multi-cellular tumor spheroids of various human cancer cell lines (U87, HepG2, A549).

A biophysical study of the interactions of palladium(II), platinum(II) and gold(III) complexes of aminopyridyl-2,2'-bipyridine ligands with RNAs and other nucleic acid structures.

Metal compounds form an attractive class of ligands for a variety of nucleic acids. Five metal complexes bearing aminopyridyl-2,2'-bipyridine tetradentate ligands and possessing a quasi-planar geometry were challenged toward different types of nucleic acid molecules including RNA polynucleotides in the duplex or triplex form, an RNA Holliday four-way junction, natural double helix DNA and a DNA G-quadruplex. The binding process was monitored comparatively using different spectroscopic and melting methods.

Ruthenium-Locked Helical Chirality: A Barrier of Inversion and Formation of an Asymmetric Macrocycle.

Upon coordination to metal centers, tetradentate ligands based on the 6,6'-bis(2″-aminopyridyl)-2,2'-bipyridine (bapbpy) structure form helical chiral complexes due to the steric clash between the terminal pyridines of the ligand. For octahedral ruthenium(II) complexes, the two additional axial ligands bound to the metal center, when different, generate diastereotopic aromatic protons that can be distinguished by NMR. Based on these geometrical features, the inversion barrier of helical [Ru(L)(RR'SO)Cl] complexes, where L is a sterically hindered bapbpy derivative and RR'SO is a chiral or achiral sulfoxide ligand, was studied by variable-temperature H NMR.

Induction of a Four-Way Junction Structure in the DNA Palindromic Hexanucleotide 5'-d(CGTACG)-3' by a Mononuclear Platinum Complex.

Four-way junctions (4WJs) are supramolecular DNA assemblies comprising four interacting DNA strands that in biology are involved in DNA-damage repair. In this study, a new mononuclear platinum(II) complex 1 was prepared that is capable of driving the crystallization of the DNA oligomer 5'-d(CGTACG)-3' specifically into a 4WJ-like motif. In the crystal structure of the 1-CGTACG adduct, the distorted-square-planar platinum complex binds to the core of the 4WJ-like motif through π-π stacking and hydrogen bonding, without forming any platinum-nitrogen coordination bonds.

Photochemical Resolution of a Thermally Inert Cyclometalated Ru(phbpy)(N-N)(Sulfoxide) Complex.

In this work a photosubstitution strategy is presented that can be used for the isolation of chiral organometallic complexes. A series of five cyclometalated complexes Ru(phbpy)(N-N)(DMSO-κS)](PF) ([1]PF-[5]PF) were synthesized and characterized, where Hphbpy = 6'-phenyl-2,2'-bipyridyl, and N-N = bpy (2,2'-bipyridine), phen (1,10-phenanthroline), dpq (pyrazino[2,3- f][1,10]phenanthroline), dppz (dipyrido[3,2- a:2',3'- c]phenazine, or dppn (benzo[ i]dipyrido[3,2- a,2',3'- c]phenazine), respectively. Due to the asymmetry of the cyclometalated phbpy ligand, the corresponding [Ru(phbpy)(N-N)(DMSO-κS)]complexes are chiral.