The collaboration between the research groups of professors Pau Ballester and José Ramón Galán-Mascarós at the Institute of Chemical Research of Catalonia (ICIQ) and the group of Dr. David Ecija at Institute IMDEA Nanoscience has allowed the development of a new chemical reaction for the synthesis of low-dimensional polymers that can be rationalised as phthalocyanine derivatives. The results obtained have been published in Nature Communications.
Surface-mediated synthesis of low-dimensional polymers from simple molecular precursors is a rapidly emerging field. In this work, the researchers introduce surface-confined thermally tunable reaction pathways as a route to select intramolecular versus intermolecular reactions yielding either monomeric phthalocyanines or low-dimensional phthalocyanine polymers, respectively.
a) STM image displaying the formation of quasi-unidimensional polymers. b) STM image and models of the majority of products between coupled monomers.
The precursor -designed and synthesised at ICIQ’s laboratories- has been deposited on a gold surface where it has been gently annealed to more than 300ºC in order to study its behaviour. When the temperature rises up to 275ºC, the polymerisation of the molecule occurs resulting in phthalocyanine unidimensional polymers (phthalocyanine tapes) that had not been synthesised so far. However, when the temperature increases to 300ºC, the polymeric growth is blocked and the precursor is transformed into individual phthalocyanines. This selectivity induced by temperature, despite being a promising strategy for increasing the synthetic versatility, had not been used on surfaces up to now. Nevertheless, this use could have huge advantages when engineering nanostructures with technological applications.
“On-surface synthesis is a promising strategy for the formation of nanostructures. This new thermally controlled reaction presents a very interesting alternative for the development of new polymeric materials, which will satisfy the growing demand from disciplines such as nanotechnology, information technology and biotechnology” -says Prof. Galán-Mascarós.
Thermal selectivity of intermolecular versus intramolecular reactions on surfaces
B. Cirera, N. Giménez-Agulló, J. Björk, F. Martínez-Peña, A. Martin-jimenez, J. Rodríguez-Fernandez, A. M. Pizarro, R. Otero, J. M. Gallego, P. Ballester, J. R. Galán-Mascarós, D. Ecija
Nature Communications, 2016, 7, 11002