Nuclear Spin Singlet States in Photoactive Molecules: From Fluorescence/NMR Bimodality to a Bimolecular Switch for Spin Singlet States. (28th January 2019)

• Record Type: Journal Article
• Authors: Yang, Shengjun; McCormick, Jeffrey; Mamone, Salvatore; Bouchard, Louis‐S.; Glöggler, Stefan
• Is Part Of: Angewandte Chemie. Volume 131:Number 9(2019)
• Page Start: 2905
• Page End: 2909
• Publication Date: 2019-01-28
• Subjects: Aggregation -- Dimere -- Fluoreszenz -- NMR-Spektroskopie -- Photoschalter; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201814198
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Nuclear spin singlet states are silent states in nuclear magnetic resonance (NMR). However, they can be probed indirectly and offer great potential for the development of contrast agents for magnetic resonance imaging (MRI). Introduced here are two novel concepts: Firstly, the bimodal NMR/fluorescence properties of 13 C2 ‐tetraphenylethylene. It possesses a long‐lived singlet state in organic solvents, and it shortens upon the addition of water. This simultaneously increases the aggregation‐induced emission (AIE) of the molecule, resulting in a substantial enhancement of fluorescence. Secondly, introduced is a bimolecular switch for singlet states based on 3‐ 2 H ‐coumarin containing an isolated proton. Upon UV‐light exposure, a dimer forms, leading to a coupling between two previously isolated protons. A nuclear spin singlet state can now be populated. Excitation with a wavelength of 254 nm results in partial ring cleavage of the molecule back to its monomer. Abstract : Licht‐Schalter : Zwei neue Entdeckungen im Bereich photoaktiver Moleküle werden beschrieben: ein bimodaler NMR‐Spektroskopie/Fluoreszenz‐Ansatz zur Aufzeichnung von Molekülen und ein bimolekularer Licht‐Schalter für Kernspin‐Singulett‐Zustände.