Long spin coherence times on C$_{59}$N-C$_{60}$ heterodimer radicals entrapped in cycloparaphenylene rings

Tanuma, Yuri (author), Knaflič, Tilen (author), Anézo, Bastien (author), Stangel, Christina (author), Volkmann, Jannis (author), Tagmatarchis, Nikos (author), Wegner, Hermann A. (author), Arčon, Denis (author), Ewels, Christopher Paul (author)

We investigate the effect of introducing C$_{60}$ to (C$_{59}$N)$_2$ and the molecular ring, [10]cycloparaphenylene ([10]CPP), using electron paramagnetic resonance (EPR) measurements supported by density functional theory (DFT) calculations. Incorporating C$_{60}$ into the system results in the formation of novel stable [10]CPP ⊃ C$_{59}$N-C$_{60}$$^•$ ⊂ [10]CPP encapsulated heterodimer radicals whose spin is localized on C$_{60}$ and manifests in EPR measurements as a signal at g = 2.0022 without any discernable hyperfine structure. This signal has an exceptionally long spin coherence lifetime of 440 μs at room temperature, far longer than any of the radical fullerene species reported in the literature and over twice that of the C$_{59}$N$^•$ ⊂ [10]CPP radical. The radicals are long-lived, with EPR signal still strong over a year after thermal activation. The [10]CPP ⊃ C$_{59}$N-C$_{60}$$^•$ ⊂ [10]CPP oligomer is more stable than C$_{59}$N$^•$ ⊂ [10]CPP radicals and becomes the predominant species at room temperature after annealing. Its formation is thermally activated with an experimental activation energy of only 0.189 eV, as compared to 0.485 eV for the pure azafullerene-[10]CPP case. The [10]CPP ⊃ C$_{59}$N-C$_{60}$$^•$ ⊂ [10]CPP radicals discovered here could be used to bridge C$_{59}$N$^•$ ⊂ [10]CPPs acting as qubits, providing effective coupling between them.

• Language: English
• Keywords: physical chemistry
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FMF - Faculty of Mathematics and Physics
• Publication status: Published
• Publication version: Version of Record
• Year: 2023
• Number of pages: Str. 6552-6561
• Numbering: Vol. 127, iss. 13
• PID: 20.500.12556/RUL-147226
• UDC: 544
• ISSN on article: 1932-7447
• DOI: 10.1021/acs.jpcc.2c09049
• COBISS.SI-ID: 148195843
• Publication date in RUL: 27.06.2023

Record is a part of a journal

• Title: The journal of physical chemistry. C
• Publisher: American Chemical Society
• ISSN: 1932-7447
• COBISS.SI-ID: 28455429

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.

Secondary language

• Language: Slovenian
• Keywords: fizikalna kemija