Cirera Borja, Giménez-Agulló Nelson, Björk Jonas, Martínez-Peña Francisco, Martin-Jimenez Alberto, Rodriguez-Fernandez Jonathan, Pizarro Ana M, Otero Roberto, Gallego José M, Ballester Pablo, Galan-Mascaros José R, Ecija David
IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, Tarragona 43007, Spain.
Nat Commun. 2016 Mar 11;7:11002. doi: 10.1038/ncomms11002.
On-surface synthesis is a promising strategy for engineering heteroatomic covalent nanoarchitectures with prospects in electronics, optoelectronics and photovoltaics. Here we report the thermal tunability of reaction pathways of a molecular precursor in order to select intramolecular versus intermolecular reactions, yielding monomeric or polymeric phthalocyanine derivatives, respectively. Deposition of tetra-aza-porphyrin species bearing ethyl termini on Au(111) held at room temperature results in a close-packed assembly. Upon annealing from room temperature to 275 °C, the molecular precursors undergo a series of covalent reactions via their ethyl termini, giving rise to phthalocyanine tapes. However, deposition of the tetra-aza-porphyrin derivatives on Au(111) held at 300 °C results in the formation and self-assembly of monomeric phthalocyanines. A systematic scanning tunnelling microscopy study of reaction intermediates, combined with density functional calculations, suggests a [2+2] cycloaddition as responsible for the initial linkage between molecular precursors, whereas the monomeric reaction is rationalized as an electrocyclic ring closure.
表面合成是一种很有前景的策略，可用于构建具有电子、光电子和光伏应用前景的杂原子共价纳米结构。在此，我们报告了分子前驱体反应途径的热可调性，以便选择分子内反应与分子间反应，分别生成单体或聚合酞菁衍生物。在室温下将带有乙基端基的四氮卟啉物种沉积在Au(111)上会形成紧密堆积的组装体。从室温退火至275°C时，分子前驱体通过其乙基端基发生一系列共价反应，生成酞菁带。然而，将四氮卟啉衍生物沉积在300°C的Au(111)上会导致单体酞菁的形成和自组装。对反应中间体进行的系统扫描隧道显微镜研究，结合密度泛函计算，表明[2+2]环加成反应是分子前驱体之间初始连接的原因，而单体反应则可解释为电环化闭环反应。
