Bis-4-aza[6]helicene: A Bis-helicenic 2,2'-Bipyridine with Chemically Triggered Chiroptical Switching Activity.

A novel enantiopure bis-helicenic 2,2'-bipyridine system was prepared using a Negishi coupling. Thanks to the bipyridine unit, the coordination with Zn and protonation processes were studied, revealing efficient tuning of photophysical (UV/visible and emission) and chiroptical properties (electronic circular dichroism and circularly polarized emission) of the system. The coordination/decoordination and protonation/deprotonation processes appeared reversible, thus constituting novel chiroptical switches.

Tetrathiafulvalene-Based Helicene Ligand in the Design of a Dysprosium Field-Induced Single-Molecule Magnet.

The design of a coordination complex that involves a ligand combining both a tetrathiafulvalene core and a helicene fragment was achieved thanks to the reaction between the new 2-{1-[2-methyl[6]helicene]-4,5-[4,5-bis(propylthio)tetrathiafulvalenyl]-1 H-benzimidazol-2-yl}pyridine ligand (L) and the Dy(hfac)·2HO metalloprecursor. Magnetic investigations showed field-induced single-molecule-magnet (SMM) behavior under an applied magnetic field of 1000 Oe for [Dy(hfac)(L)]·0.5CHCl, while experimentally oriented single-crystal magnetic measurements allowed for determination of the magnetic anisotropy orientation.

Unexpected self-assembly of chiral triangles from 90° chiral di-Pt(II) acceptors.

Two unexpected chiral organometallic triangles rather than squares from newly designed 90° chiral di-Pt(II) acceptors were obtained through coordination-driven self-assembly. Their structures were well characterized by multinuclear NMR ((1)H and (31)P) and variable-temperature NMR experiments, ESI-TOF-MS, and elemental analysis. The PM6 semiempirical molecular simulation was employed for the interpretation of the formation and stability of such chiral triangles.