Conception, synthèse et caractérisation de tecton Janus photoisomérisables aptes à l'auto-assemblage sur HOPG : vers le développment de trappes optiques

Le résumé fourni par la source

The nanostructuring of surfaces by supramolecular self-assembly of organic molecules enables the creation of nano-porous networks and controlling the opening/closing of these cavities is still a challenge. Recently, a new approach has been developed that combines the 2D self-assembly into a nano-porous network and the control of the organization in the third dimension (Janus tecton concept). Herein, this concept was used to place a photoswitch above cavities. The azobenzenes were chosen as photoswitch. Five Janus tectons were then designed, synthesized and characterized. They are made of two decks linked by a dithia-[3. 3]cyclophane bridge. The lower deck (identical for each compound) leads to the 2D self-assembly on HOPG into a nano-porous network. Each upper deck was designed to incorporate an azobenzene with intrinsic photoisomerization properties and possessing an optical gap smaller than the one of the lower deck to avoid loss of optical properties. The photoisomerization in solution was observed and the self-assembly on HOPG was demonstrated by Scanning Tunneling Microscopy (STM) at the liquid/solid interface. Moreover, the addition of hexabenzocoronene type guest molecules into the Janus tecton nano-porous network has proven its host-guest properties. Finally the photoisomerization on HOPG was highlighted with the STM study of the optimal Janus tecton (photoisomerization time in solution appropriate for STM study and easily observable self-assembly on HOPG surface). Ongoing studies focus on controlling the access of guest molecules to the cavities via cis-trans photoisomerization of the azobenzenes.

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