Synthesis of a new family of nanocars including a bistable state

Work package:
In the CEMES NanoSciences team, one of the current themes concerns the synthesis of molecular machines[1] whose mechanical properties are studied at the single-molecule scale using scanning tunneling microscopy (STM). [2] In particular, we wish to control the translational movements of molecular objects adsorbed on a surface, and several families of nanovoitures have been designed and synthesized in recent years. 3] The architecture of these nanovoitures follows a technomimetic approach and comprises two to four triptycene wheels around a rigid polyaromatic[3a] (Fig. 1, left) or porphyrinic[3b] (Fig. 1, center) chassis. The porphyrinic frame has the added advantage of incorporating a metallic center, which can be exploited for transporting small molecules via axial coordination. Following on from this work, this internship aims to synthesize a new type of nanovoiture, this time incorporating two metal centers within a salen and phenanthroline-type framework (Fig. 1, in the box on the right). The special feature of this system is its bistable state. Indeed, the molecule in state A deposited on a surface could switch to state B by monoelectronic reduction under the effect of the STM tip. It has been shown experimentally in the GNS group that the selective reduction of a Cu(II) ion on a surface leads to a structural modification of the molecule, which loses its planarity by moving from a plano-square geometry to a tetrahedral geometry.[4] This change of state would modulate the movement of the nanocarrier on the surface by acting as a brake.