Desymmetrization on both ligands of pentaphenylcyclopentadienylhydrotris(indazolyl) borate ruthenium(II) complexes: Prototypes of organometallic molecular gears and motors

Star-Shaped Ruthenium Complexes as Prototypes of Molecular Gears

The design and synthesis of two families of molecular-gear prototypes is reported, with the aim of assembling them into trains of gears on a surface and ultimately achieving controlled intermolecular gearing motion. These piano-stool ruthenium complexes incorporate a hydrotris(indazolyl)borate moiety as tripodal rotation axle and a pentaarylcyclopentadienyl ligand as star-shaped cogwheel, equipped with five teeth ranging from pseudo-1D aryl groups to large planar 2D paddles. A divergent synthetic approach was followed, starting from a pentakis(p-bromophenyl)cyclopentadienyl ruthenium(II) complex as key precursor or from its iodinated counterpart, obtained by copper-catalyzed aromatic Br/I exchange. Subsequent fivefold cross-coupling reactions with various partners allowed high structural diversity to be reached and yielded molecular-gear prototypes with aryl-, carbazole-, BODIPY- and porphyrin-derived teeth of increasing size and length.

Modular synthesis of pentaarylcyclopentadienyl Ru-based molecular machines via sequential Pd-catalysed cross couplings

A dissymmetric piano-stool ruthenium(ii) complex as a key building block in the modular synthesis of molecular cogwheel and winch prototypes.

Synthesis of Functionalized Mono-, Bis-, and Trisethynyltriptycenes for One-Dimensional Self-Assembly on Surfaces

This paper describes the synthesis of triptycene-based building blocks that are able to interact through hydrogen bonds to form one-dimensional self-assembled motifs on surfaces. We designed 9,10-diethynyltriptycene derivatives functionalized at the ethynyl end groups by a variety of hydrogen-bonding groups for homomolecular recognition and complementary building blocks for heteromolecular recognition. We also present the synthesis of bis- and trisethynyltriptycenes with terminal alkyne functional groups available for on-surface azide-alkyne cycloaddition reaction to expand the potential of the triptycene building block.