{"title":"通过抑制卡沙规则实现短波长发射的 NHC 衍生碳中心发光自由基","authors":"Can Chen, Xin Li, Xinhua Ouyang, Ying-Feng Han","doi":"10.1007/s11426-024-2003-0","DOIUrl":null,"url":null,"abstract":"<p>Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes (OLEDs), attributed to their unique emission properties originating from the doublet spin state. However, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength region. Designing luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission (383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons (PAHs) (2-naphthyl, <b>2a</b><sup><b>I</b></sup> and <b>2b</b><sup><b>I</b></sup>; 2-phenanthryl, <b>2a</b><sup><b>II</b></sup> and <b>2b</b><sup><b>II</b></sup>; 2-anthryl, <b>2a</b><sup><b>III</b></sup> and <b>2b</b><sup><b>III</b></sup>; 3-phenanthryl, <b>2a</b><sup><b>IV</b></sup> and <b>2b</b><sup><b>IV</b></sup>). Theoretical calculations reveal that the introduction of PAHs significantly increases the Δ<i>E</i><sub>D2-D1</sub> in <b>2a</b><sup><b>I–III</b></sup> and <b>2b</b><sup><b>I–III</b></sup> compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha’s rule, thereby overcoming the limitations imposed by their narrow bandgap. For <b>2a</b><sup><b>IV</b></sup> and <b>2b</b><sup><b>IV</b></sup>, despite a moderately large Δ<i>E</i><sub>D2-D1</sub> value, the Δ<i>E</i><sub>D3-D1</sub> value exceeds 1 eV, indicating that their emission likely originates from the D3 state. Furthermore, we utilized <b>2a</b><sup><b>III</b></sup> and <b>2b</b><sup><b>III</b></sup> as emissive materials in OLEDs, resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.</p>","PeriodicalId":772,"journal":{"name":"Science China Chemistry","volume":null,"pages":null},"PeriodicalIF":10.4000,"publicationDate":"2024-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"NHC-derived carbon-centered luminescent radicals with short-wavelength emission via suppression of Kasha’s rule\",\"authors\":\"Can Chen, Xin Li, Xinhua Ouyang, Ying-Feng Han\",\"doi\":\"10.1007/s11426-024-2003-0\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes (OLEDs), attributed to their unique emission properties originating from the doublet spin state. However, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength region. Designing luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission (383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons (PAHs) (2-naphthyl, <b>2a</b><sup><b>I</b></sup> and <b>2b</b><sup><b>I</b></sup>; 2-phenanthryl, <b>2a</b><sup><b>II</b></sup> and <b>2b</b><sup><b>II</b></sup>; 2-anthryl, <b>2a</b><sup><b>III</b></sup> and <b>2b</b><sup><b>III</b></sup>; 3-phenanthryl, <b>2a</b><sup><b>IV</b></sup> and <b>2b</b><sup><b>IV</b></sup>). Theoretical calculations reveal that the introduction of PAHs significantly increases the Δ<i>E</i><sub>D2-D1</sub> in <b>2a</b><sup><b>I–III</b></sup> and <b>2b</b><sup><b>I–III</b></sup> compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha’s rule, thereby overcoming the limitations imposed by their narrow bandgap. For <b>2a</b><sup><b>IV</b></sup> and <b>2b</b><sup><b>IV</b></sup>, despite a moderately large Δ<i>E</i><sub>D2-D1</sub> value, the Δ<i>E</i><sub>D3-D1</sub> value exceeds 1 eV, indicating that their emission likely originates from the D3 state. Furthermore, we utilized <b>2a</b><sup><b>III</b></sup> and <b>2b</b><sup><b>III</b></sup> as emissive materials in OLEDs, resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.</p>\",\"PeriodicalId\":772,\"journal\":{\"name\":\"Science China Chemistry\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":10.4000,\"publicationDate\":\"2024-06-27\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Science China Chemistry\",\"FirstCategoryId\":\"1\",\"ListUrlMain\":\"https://doi.org/10.1007/s11426-024-2003-0\",\"RegionNum\":1,\"RegionCategory\":\"化学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CHEMISTRY, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Science China Chemistry","FirstCategoryId":"1","ListUrlMain":"https://doi.org/10.1007/s11426-024-2003-0","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
NHC-derived carbon-centered luminescent radicals with short-wavelength emission via suppression of Kasha’s rule
Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes (OLEDs), attributed to their unique emission properties originating from the doublet spin state. However, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength region. Designing luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission (383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons (PAHs) (2-naphthyl, 2aI and 2bI; 2-phenanthryl, 2aII and 2bII; 2-anthryl, 2aIII and 2bIII; 3-phenanthryl, 2aIV and 2bIV). Theoretical calculations reveal that the introduction of PAHs significantly increases the ΔED2-D1 in 2aI–III and 2bI–III compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha’s rule, thereby overcoming the limitations imposed by their narrow bandgap. For 2aIV and 2bIV, despite a moderately large ΔED2-D1 value, the ΔED3-D1 value exceeds 1 eV, indicating that their emission likely originates from the D3 state. Furthermore, we utilized 2aIII and 2bIII as emissive materials in OLEDs, resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.
期刊介绍:
Science China Chemistry, co-sponsored by the Chinese Academy of Sciences and the National Natural Science Foundation of China and published by Science China Press, publishes high-quality original research in both basic and applied chemistry. Indexed by Science Citation Index, it is a premier academic journal in the field.
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