Abstract
Riemann surfaces are deformed versions of the complex plane in mathematics. Locally they look like patches of the complex plane, but globally, the topology may deviate from a plane. Nanostructured graphitic carbon materials resembling a Riemann surface with helicoid topology are predicted to have interesting electronic and photonic properties. However, fabrication of such processable and large π-extended nanographene systems has remained a major challenge. Here, we report a bottom-up synthesis of a metal-free carbon nanosolenoid (CNS) material with a low optical bandgap of 1.97 eV. The synthesis procedure is rapid and possible on the gram scale. The helical molecular structure of CNS can be observed by direct low-dose high-resolution imaging, using integrated differential phase contrast scanning transmission electron microscopy. Magnetic susceptibility measurements show paramagnetism with a high spin density for CNS. Such a π-conjugated CNS allows for the detailed study of its physical properties and may form the base of the development of electronic and spintronic devices containing CNS species.
Highlights
Riemann surfaces are deformed versions of the complex plane in mathematics
By comparing the solid-state 2D 1H-1H double-quantum singlequantum (DQ-SQ) nuclear magnetic resonance (NMR) correlation spectra of P1 and carbon nanosolenoid (CNS), the results show that the 1H-1H autocorrelation signals of the aromatic protons in P1 disappeared after graphitization to CNS and the aromatic protons in CNS are far away from each other, which is consistent with the structural characteristics of CNS
In summary, we report a facile bottom-up synthesis of a longitudinally π-extended carbon nanosolenoid (CNS) from a hexaphenylbenzene precursor by a Pd-mediated Suzuki–Miyaura coupling followed by the Scholl reaction for cyclodehydrogenation
Summary
Riemann surfaces are deformed versions of the complex plane in mathematics. Locally they look like patches of the complex plane, but globally, the topology may deviate from a plane. Nanostructured graphitic carbon materials resembling a Riemann surface with helicoid topology are predicted to have interesting electronic and photonic properties. Fabrication of such processable and large π-extended nanographene systems has remained a major challenge. Nanostructured graphitic carbons with zigzag edges are predicted to possess spin-polarized electronic edge states and can play important roles in graphene-based spintronics[11,12]. The design and synthesis of curved large π-extended graphenebased nanomaterials have attracted great research interest in the quest to develop carbon nanostructures with distinctive geometric shapes and optoelectronic properties.
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