Intermolecular electronic coupling of 9-methyl-9 H -dibenzo[ a ,[ c ] carbazole for strong emission in aggregated state
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tps://doi.org/10.1007/s11426-020-9814-7
SPECIAL ISSUE: 2020 Emerging Investigator Issue
Intermolecular electronic coupling of 9-methyl-9H-dibenzo[a,c] carbazole for strong emission in aggregated state by substituent effect 1
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Fan Liu , Qiuyan Liao , Jinfeng Wang , Yanbing Gong , Qianxi Dang , Weidong Ling , 1 1* 1,2* Mengmeng Han , Qianqian Li & Zhen Li 1
Sauvage Center for Molecular Sciences, Department of Chemistry, Wuhan University, Wuhan 430072, China; 2 Institute of Molecular Aggregation Science, Tianjin University, Tianjin 300072, China Received May 31, 2020; accepted July 2, 2020; published online August 13, 2020
Bright emission of organic luminogens at aggregated state has attracted increasing attention for their potential applications in opto-electronic devices and bio-/chemo-sensors. In this article, upon the introduction of different substituents (Br, Ph and TPh) to the large conjugated core of 9-methyl-9H-dibenzo[a,c]carbazole (DBC) moiety, the resultant luminogens demonstrated PL quantum yields in solid state ranging from 4.81% to 47.39%. Through the systematic investigation of molecular packing, together with theory calculation, the strong intermolecular electronic coupling in the dimers is proved as the main factor to the bright emission in the solid state. The results afforded a new avenue to investigate the intrinsic relationship among the molecular structures, packing modes and emission properties. photoluminescence, substituent effect, molecular packing, electronic coupling Citation:
Liu F, Liao Q, Wang J, Gong Y, Dang Q, Ling W, Han M, Li Q, Li Z. Intermolecular electronic coupling of 9-methyl-9H-dibenzo[a,c]carbazole for strong emission in aggregated state by substituent effect. Sci China Chem, 2020, 63, https://doi.org/10.1007/s11426-020-9814-7
1 Introduction The design and synthesis of organic fluorescence materials have been a hot topic for their wide applications such as data storage, photoswitches, organic light-emitting diodies (OLEDs), organic light-emitting transistor (OLET) devices and bioimaging [1–4]. In aggregated states, the properties of these luminogens are governed by the whole collective with different molecular packing modes, rather than individual molecules [1c]. Until now, considerable progress of luminescence materials has been made with different molecule structures, but the relationship between molecular packing characteristics of organic materials and the resultant emission properties is still required to be further investigated.
Generally, the π-π stacking of aromatic rings is always considered to have the negative effect on luminescence property in the solid state, mainly due to the possible nonradiative transitions by π-π interactions [5]. Thus, with the aim to achieve the strong emission in the aggregate state, many strategies of molecular design have been emerged to suppress the π-π interactions of conjugated planes, such as the twisted molecular configurations, the introduction of steric hindrance between π-planes, and the fixed molecular cages
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