Light-Induced Contraction/Expansion of 1D Photoswitchable Metallopolymer Monitored at the Solid-Liquid Interface

EL GARAH, Mohamed, BORRE, Etienne, CIESIELSKI, Artur, DIANAT, Arezoo, GUTIERREZ, Rafael, CUNIBERTI, Gianaurelio, BELLEMIN-LAPONNAZ, Stephane, MAURO, Matteo et SAMORI, Paolo, 2017. Light-Induced Contraction/Expansion of 1D Photoswitchable Metallopolymer Monitored at the Solid-Liquid Interface. Small [en ligne]. 20 octobre 2017. Vol. 13, n° 40pp. 1701790. [Consultésans date]. DOI 10.1002/smll.201701790. Consulté de : http://onlinelibrary.wiley.com.scd-rproxy.u-strasbg.fr/doi/10.1002/smll.201701790/fullThe use of a bottom-up approach to the fabrication of nanopatterned functional surfaces, which are capable to respond to external stimuli, is of great current interest. Herein, the preparation of light-responsive, linear supramolecular metallopolymers constituted by the ideally infinite repetition of a ditopic ligand bearing an azoaryl moiety and Co(II) coordination nodes is described. The supramolecular polymerization process is followed by optical spectroscopy in dimethylformamide solution. Noteworthy, a submolecularly resolved scanning tunneling microscopy (STM) study of the in situ reversible trans-to-cis photoisomerization of a photoswitchable metallopolymer that self-assembles into 2D crystalline patterns onto a highly oriented pyrolytic graphite surface is achieved for the first time. The STM analysis of the nanopatterned surfaces is corroborated by modeling the physisorbed species onto a graphene slab before and after irradiation by means of density functional theory calculation. Significantly, switching of the monolayers consisting of supramolecular Co(II) metallopolymer bearing trans-azoaryl units to a novel pattern based on cis isomers can be triggered by UV light and reversed back to the trans conformer by using visible light, thereby restoring the trans-based supramolecular 2D packing. These findings represent a step forward toward the design and preparation of photoresponsive “smart” surfaces organized with an atomic precision.1. .