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Non-benzenoid carbocyclic rings are postulated to serve as important structural elements toward tuning the chemical and electronic properties of extended polycyclic aromatic hydrocarbons (PAHs, or namely nanographenes), necessitating a rational and atomically-precise synthetic approach toward their fabrication. Here, using a combined bottom-up in-solution and on-surface synthetic approach, we report the synthesis of non-benzenoid open-shell nanographenes containing two pairs of embedded pentagonal and heptagonal rings. Extensive characterization of the resultant nanographene in solution shows a low optical gap, and an open-shell singlet ground state with a low singlet-triplet gap. Employing ultra-high-resolution scanning tunneling microscopy and spectroscopy, we conduct atomic-scale structural and electronic studies on a cyclopenta-fused derivative on a Au(111) surface. The resultant 5-7 rings embedded nanographene displays an extremely narrow energy gap of 0.27 eV and exhibits a pronounced open-shell biradical character close to one (y0=0.92). Our experimental results are supported by mean-field and multi-configurational quantum chemical calculations. Access to large nanographenes with a combination of non-benzenoid topologies and open-shell character should have wide implications in harnessing new functionalities toward the realization of future organic electronic and spintronic devices.
This article was published in the following journal.
Name: Journal of the American Chemical Society
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The genus Lepus, in the family Leporidae, order LAGOMORPHA. Hares are born above ground, fully furred, and with their eyes and ears open. In contrast with RABBITS, hares have 24 chromosome pairs.
A plant genus, of the family ONAGRACEAE, which is the subject of genetic studies. The floral aroma is attributed to benzenoid esters and benzylacetate.
Highly repeated sequences, 6K-8K base pairs in length, which contain RNA polymerase II promoters. They also have an open reading frame that is related to the reverse transcriptase of retroviruses but they do not contain LTRs (long terminal repeats). Copies of the LINE 1 (L1) family form about 15% of the human genome. The jockey elements of Drosophila are LINEs.
Implants used to reconstruct and/or cosmetically enhance the female breast. They have an outer shell or envelope of silicone elastomer and are filled with either saline or silicone gel. The outer shell may be either smooth or textured.
Changing an operative procedure from an endoscopic surgical procedure to an open approach during the INTRAOPERATIVE PERIOD.