Multiple Emission of Phosphonium Fluorophores Harnessed by the Pathways of Photoinduced Counterion Migration. Issue 19 (24th February 2022)

• Record Type: Journal Article
• Authors: Belyaev, Andrey; Su, Bo‐Kang; Cheng, Yu‐Hsuan; Liu, Zong‐Ying; Khan, Nasrulla Majid; Karttunen, Antti J.; Chou, Pi‐Tai; Koshevoy, Igor O.
• Is Part Of: Angewandte Chemie international edition. Volume 61:Issue 19(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-02-24
• Subjects: Charge Transfer -- Donor–Acceptor Systems -- Dual Emission -- Ion Pairs -- Phosphonium; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202115690
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: In the emerging field of intramolecular charge transfer induced counterion migration, we report the new insights into photophysical features of luminescent donor–acceptor phosphonium dyes (D−π−) n A + [X − ] (π=−(C6 H4 ) x −). The unique connectivity of the phosphorus atom affords multipolar molecules with a variable number of arms and the electronic properties of the acceptor group. In the ion‐paired form, the transition from dipolar to quadrupolar configuration enhances the low energy migration‐induced band by providing the additional pathways for anion motion. The multipolar architecture, adjustable lengths of the π‐spacers and the nature of counterions allow for efficient tuning of the emission and achieving nearly pure white light with quantum yields around 30 %. The methyl substituent at the phosphorus atom reduces the rate of ion migration and suppresses the red shifted bands, simultaneously improving total emission intensity. The results unveil the harnessing of the multiple emission of phosphonium fluorophores by anion migration via structure and branching of donor–acceptor arms. Abstract : The photophysical properties of a series of multipolar donor–acceptor phosphonium fluorophores (D−π−) n A + [X − ] have been investigated. These dyes exhibit steady‐state panchromatic luminescence attributed to the photoinduced counterion migration. The intra‐ion‐pair dynamics and the fluorescence response can be rationally tuned on the molecular level that might broaden the scope of functionalities and stimulate the development of new ionic systems.