2D network structure controlled by heat

11-May-2009 - Switzerland

European collaboration of scientists creates an H-bonded 2D network, in which changing temperature changes the 2D conformation.

Davide Bonifazi has completed research both at the University of Namur, Brussels, and the University of Trieste, Italy and has collaborated with Meike Stöhr from the University of Basel, Switzerland and colleagues from the three universities. This collaboration reports the formation of an H-bonded porous hexagonal network which evolves into a close-packed rhombic pattern after thermally-induced trans-cis inversion of the conformation of the amidic groups.

‘We have shown using scanning tunnelling microscopy (STM) that 8-conjugated molecules bearing complementary H-bonding sites can self-organise into complex 2D porous networks on surfaces' Bonifazi explains. 'It is possible to thermally induce a phase transition (from a porous hexagonal to a rhombic close-packed 2D assembly) by exploiting conformational degrees of freedom.'

‘The need for highly organised materials at the molecular level has become increasingly apparent from basic science and applied technologies’ says Bonfazi. He explains that 'the current state of research in this field is still far from being a sophisticated and targeted "bottom-up" approach towards the fabrication of predictable supramolecular entities, usable in real-world applications.’

The group is planning to develop other networks which can be tuned in size and shape using external stimuli, by selecting appropriate spacing groups and recognition moieties.

Original article: Matena et al.; "Conformation-controlled networking of H-bonded assemblies on surfaces"; Chem. Commun. 2009

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