Self‐Assembled Helical Arrays for the Stabilization of the Triplet State. Issue 31 (5th June 2020)

• Record Type: Journal Article
• Authors: Nidhankar, Aakash D.; Goudappagouda, ; Mohana Kumari, Divya S.; Chaubey, Shailendra Kumar; Nayak, Rashmi; Gonnade, Rajesh G.; Kumar, G. V. Pavan; Krishnan, Retheesh; Babu, Sukumaran Santhosh
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 31(2020)
• Page Start: 13079
• Page End: 13085
• Publication Date: 2020-06-05
• Subjects: carbazole -- helicity -- phenylmethanone -- ultralong phosphorescence -- waveguiding; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202005105
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Room‐temperature phosphorescence of metal and heavy atom‐free organic molecules has emerged as an area of great potential in recent years. A rational design played a critical role in controlling the molecular ordering to impart efficient intersystem crossing and stabilize the triplet state to achieve room‐temperature ultralong phosphorescence. However, in most cases, the strategies to strengthen phosphorescence efficiency have resulted in a reduced lifetime, and the available nearly degenerate singlet‐triplet energy levels impart a natural competition between delayed fluorescence and phosphorescence, with the former one having the advantage. Herein, an organic helical assembly supports the exhibition of an ultralong phosphorescence lifetime. In contrary to other molecules, 3, 6‐phenylmethanone functionalized 9‐hexylcarbazole exhibits a remarkable improvement in phosphorescence lifetime (>4.1 s) and quantum yield (11 %) owing to an efficient molecular packing in the crystal state. A right‐handed helical molecular array act as a trap and exhibits triplet exciton migration to support the exceptionally longer phosphorescence lifetime. Abstract : A right‐handed helical molecular array of phenylmethanone functionalized carbazole acts as a trap and exhibits triplet exciton migration to support an exceptionally long phosphorescence lifetime.