title: Thermal selectivity of intermolecular versus intramolecular reactions on surfaces.
abstract: 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.
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Borja
authors.initials: B
authors.lastname: Cirera
authors.affiliation: Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, Tarragona 43007, Spain.
authors.forename: Nelson
authors.initials: N
authors.lastname: Giménez-Agulló
authors.affiliation: Department of Physics, Chemistry and Biology, IFM, Linköping University, 58183 Linköping, Sweden.
authors.forename: Jonas
authors.initials: J
authors.lastname: Björk
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Francisco
authors.initials: F
authors.lastname: Martínez-Peña
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Martin-Jimenez
authors.affiliation: Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, c/Francisco Tomás y Valiente 7, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Rodriguez-Fernandez
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Ana M
authors.initials: AM
authors.lastname: Pizarro
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.|Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid, c/Francisco Tomás y Valiente 7, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Otero
authors.affiliation: Instituto de Ciencia de Materiales de Madrid, c/ Sor Juana Inés de la Cruz 3, Cantoblanco, 28049 Madrid, Spain.
authors.forename: José M
authors.initials: JM
authors.lastname: Gallego
authors.affiliation: Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, Tarragona 43007, Spain.|Catalan Institution for Research and Advanced Studies, Passeig Lluis Companys 23, Barcelona 08010, Spain.
authors.forename: Pablo
authors.identifier: http://orcid.org/0000-0001-8377-6610
authors.initials: P
authors.lastname: Ballester
authors.affiliation: Institute of Chemical Research of Catalonia, Barcelona Institute of Science and Technology, Avinguda Països Catalans 16, Tarragona 43007, Spain.|Catalan Institution for Research and Advanced Studies, Passeig Lluis Companys 23, Barcelona 08010, Spain.
authors.forename: José R
authors.initials: JR
authors.lastname: Galan-Mascaros
authors.affiliation: IMDEA Nanoscience, c/Faraday 9, Cantoblanco, 28049 Madrid, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Ecija
mesh_terms: D061565:Cycloaddition Reaction; D004581:Electronics; D006046:Gold / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry*; D054833:Isoindoles; D016252:Microscopy, Scanning Tunneling; D036103:Nanotechnology / Q000379:methods*; D011166:Porphyrins / Q000737:chemistry*; D011789:Quantum Theory; D013499:Surface Properties; D013696:Temperature
chemical_list: D007211:Indoles; D054833:Isoindoles; D011166:Porphyrins; D006046:Gold; C013647:phthalocyanine