Pavel A. Sobov , Alexey V. Kuzmin , Artem F. Shevchun , Maxim A. Faraonov , Salavat S. Khasanov , Akihiro Otsuka , Hideki Yamochi , Hiroshi Kitagawa , Dmitri V. Konarev
{"title":"三萜烯(TPC-X)中取代基的大小对层状二维有机金属(MDABCO+)(C60•−)(TPC-X)磁性和导电性的影响,其中X = H, Br和I","authors":"Pavel A. Sobov , Alexey V. Kuzmin , Artem F. Shevchun , Maxim A. Faraonov , Salavat S. Khasanov , Akihiro Otsuka , Hideki Yamochi , Hiroshi Kitagawa , Dmitri V. Konarev","doi":"10.1016/j.synthmet.2025.117904","DOIUrl":null,"url":null,"abstract":"<div><div>Modification of the neutral triptycene TPC-X molecule by increasing the size of the X substituent at the 9th position from X = H to Br and I affects the magnetic and conducting properties of the (MDABCO<sup>+</sup>)(C<sub>60</sub><sup>•−</sup>)(TPC-X) salts (<strong>1</strong>–<strong>3</strong>, respectively), where MDABCO<sup>+</sup> is <em>N</em>-methyldiazabicyclooctanium. These salts feature hexagonal fullerene layers composed of C<sub>60</sub><sup>•−</sup>, which remain undimerized owing to spatial separation by TPC-X. Two distinct fullerene layers, <em>A</em> and <em>B</em>, differ in their surroundings. The calculated bandwidth of 0.133–0.141 eV for <strong>3</strong> indicates a narrow band nature and as a result both fullerene layers are close to a Mott insulating state. Only one type of fullerene layers demonstrate metallic conductivity in <strong>2</strong> and <strong>3</strong>, while another type of fullerene layers have localized electronic state and shows strong antiferromagnetic spin coupling down to low temperatures. Magnetic coupling in <strong>2</strong> and <strong>3</strong> follows the Heisenberg model for 2D hexagonal layers, with <em>J</em> =−28 and −34 cm<sup>−1</sup>, respectively. The 2D metallic conductivity enables the observation of a Dysonian-type electron paramagnetic resonance signal from oriented single crystals of <strong>2</strong> and <strong>3</strong>, similar to <strong>1</strong>. Heating <strong>2</strong> and <strong>3</strong> above 300 K decreases their A/B ratio, reaches unity above 350 K, signaling a crossover to a nonmetallic state. The interfullerene center-to-center (ctc) distances increase upon heating, essentially reducing overlap and transfer integrals in (MDABCO<sup>+</sup>)(C<sub>60</sub><sup>•−</sup>)(TPC-X). Because these salts are narrow-band metals, such an increase in ctc distances may drive a transition of these metals to a Mott-insulating state.</div></div>","PeriodicalId":22245,"journal":{"name":"Synthetic Metals","volume":"313 ","pages":"Article 117904"},"PeriodicalIF":4.6000,"publicationDate":"2025-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Effect of the size of the substituents in triptycene (TPC-X) on the magnetic and conducting properties of the layered 2D organic metals (MDABCO+)(C60•−)(TPC-X), where X = H, Br, and I\",\"authors\":\"Pavel A. Sobov , Alexey V. Kuzmin , Artem F. Shevchun , Maxim A. Faraonov , Salavat S. Khasanov , Akihiro Otsuka , Hideki Yamochi , Hiroshi Kitagawa , Dmitri V. Konarev\",\"doi\":\"10.1016/j.synthmet.2025.117904\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Modification of the neutral triptycene TPC-X molecule by increasing the size of the X substituent at the 9th position from X = H to Br and I affects the magnetic and conducting properties of the (MDABCO<sup>+</sup>)(C<sub>60</sub><sup>•−</sup>)(TPC-X) salts (<strong>1</strong>–<strong>3</strong>, respectively), where MDABCO<sup>+</sup> is <em>N</em>-methyldiazabicyclooctanium. These salts feature hexagonal fullerene layers composed of C<sub>60</sub><sup>•−</sup>, which remain undimerized owing to spatial separation by TPC-X. Two distinct fullerene layers, <em>A</em> and <em>B</em>, differ in their surroundings. The calculated bandwidth of 0.133–0.141 eV for <strong>3</strong> indicates a narrow band nature and as a result both fullerene layers are close to a Mott insulating state. Only one type of fullerene layers demonstrate metallic conductivity in <strong>2</strong> and <strong>3</strong>, while another type of fullerene layers have localized electronic state and shows strong antiferromagnetic spin coupling down to low temperatures. Magnetic coupling in <strong>2</strong> and <strong>3</strong> follows the Heisenberg model for 2D hexagonal layers, with <em>J</em> =−28 and −34 cm<sup>−1</sup>, respectively. The 2D metallic conductivity enables the observation of a Dysonian-type electron paramagnetic resonance signal from oriented single crystals of <strong>2</strong> and <strong>3</strong>, similar to <strong>1</strong>. Heating <strong>2</strong> and <strong>3</strong> above 300 K decreases their A/B ratio, reaches unity above 350 K, signaling a crossover to a nonmetallic state. The interfullerene center-to-center (ctc) distances increase upon heating, essentially reducing overlap and transfer integrals in (MDABCO<sup>+</sup>)(C<sub>60</sub><sup>•−</sup>)(TPC-X). Because these salts are narrow-band metals, such an increase in ctc distances may drive a transition of these metals to a Mott-insulating state.</div></div>\",\"PeriodicalId\":22245,\"journal\":{\"name\":\"Synthetic Metals\",\"volume\":\"313 \",\"pages\":\"Article 117904\"},\"PeriodicalIF\":4.6000,\"publicationDate\":\"2025-06-07\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Synthetic Metals\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0379677925000803\",\"RegionNum\":3,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATERIALS SCIENCE, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Synthetic Metals","FirstCategoryId":"88","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0379677925000803","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
Effect of the size of the substituents in triptycene (TPC-X) on the magnetic and conducting properties of the layered 2D organic metals (MDABCO+)(C60•−)(TPC-X), where X = H, Br, and I
Modification of the neutral triptycene TPC-X molecule by increasing the size of the X substituent at the 9th position from X = H to Br and I affects the magnetic and conducting properties of the (MDABCO+)(C60•−)(TPC-X) salts (1–3, respectively), where MDABCO+ is N-methyldiazabicyclooctanium. These salts feature hexagonal fullerene layers composed of C60•−, which remain undimerized owing to spatial separation by TPC-X. Two distinct fullerene layers, A and B, differ in their surroundings. The calculated bandwidth of 0.133–0.141 eV for 3 indicates a narrow band nature and as a result both fullerene layers are close to a Mott insulating state. Only one type of fullerene layers demonstrate metallic conductivity in 2 and 3, while another type of fullerene layers have localized electronic state and shows strong antiferromagnetic spin coupling down to low temperatures. Magnetic coupling in 2 and 3 follows the Heisenberg model for 2D hexagonal layers, with J =−28 and −34 cm−1, respectively. The 2D metallic conductivity enables the observation of a Dysonian-type electron paramagnetic resonance signal from oriented single crystals of 2 and 3, similar to 1. Heating 2 and 3 above 300 K decreases their A/B ratio, reaches unity above 350 K, signaling a crossover to a nonmetallic state. The interfullerene center-to-center (ctc) distances increase upon heating, essentially reducing overlap and transfer integrals in (MDABCO+)(C60•−)(TPC-X). Because these salts are narrow-band metals, such an increase in ctc distances may drive a transition of these metals to a Mott-insulating state.
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