abstract
On-surface synthesis has emerged as an attractive method for the atomically precise synthesis of new molecular nanostructures, being complementary to the widespread approach based on solution chemistry. It has been particularly successful in the synthesis of graphene nanoribbons and nanographenes. In both cases, the target compound is often generated through cyclodehydrogenation reactions, leading to planarization and the formation of hexagonal rings. To improve the flexibility and tunability of molecular units, however, the incorporation of other, nonbenzenoid, subunits is highly desirable. In this letter, we thoroughly analyze sequential cyclodehydrogenation reactions with a custom-designed molecular precursor. We demonstrate the step-by-step formation of hexagonal and pentagonal rings from the nonplanar precursor within fjord and cove regions, respectively. Computer models comprehensively support the experimental observations, revealing that both reactions imply an initial hydrogen abstraction and a final [1,2] hydrogen shift, but the formation of a pentagonal ring proceeds through a radical mechanism.
keywords
ASSISTED CYCLODEHYDROGENATION; GRAPHENE NANORIBBONS; CHEMICAL-STRUCTURE; NANOSTRUCTURES; POLYMERIZATION; MOLECULE; ROUTE
subject category
Chemistry; Science & Technology - Other Topics; Materials Science; Physics
authors
Zuzak, R; Quiroga, S; Engelund, M; Pérez, D; Peña, D; Godlewski, S; Melle-Franco, M
our authors
Manuel Melle-Franco
Principal ResearcherProjects
Projeto de Investigação Exploratória: Manuel Melle (IF Manuel Melle)
CICECO - Aveiro Institute of Materials (UIDB/50011/2020)
CICECO - Aveiro Institute of Materials (UIDP/50011/2020)
Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)
acknowledgements
We acknowledge financial support from the National Science Center, Poland (2017/26/E/ST3/00855). R.Z. acknowledges the support received from the National Science Center, Poland (2017/24/T/ST5/00262). In addition, support through the project IF/00894/2015 and within the scope of the project CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020, and LA/P/0006/2020) financed by national funds through the FCT/MEC (PIDDAC) is gratefully acknowledged. We also acknowledge financial support from the Spanish MCIN/AEI/10.13039/501100011033 (PID2019-107338RB-C62, PID2019-110037GB-I00, TED2021-132388B-C42, and PCI2019-111933-2), Xunta de Galicia (ED431C 2020/22, ED431H 2020/21, and Centro Singular de Investigacion de Galicia accreditation 2019-2022, ED431G 2019/03), and the European Regional Development Fund (ERDF).