Luminescent Trityl-based Diradicaloids: A Theoretical and Experimental Assessment of Charge-Resonance in Low-Lying Excited States
The tris(2,4,6-trichlorophenyl)methyl radical (TTM) has inspired the synthesis of several luminescent diradicaloids, providing an extraordinary opportunity to control the nature of the low-lying excited states by fine-tuning the diradical character. However, the photophysical properties of TTM-deriv...
| Autores: | , , , , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/393992 |
| Acceso en línea: | http://hdl.handle.net/10261/393992 https://api.elsevier.com/content/abstract/scopus_id/105003136241 |
| Access Level: | acceso abierto |
| Palabra clave: | Chichibabin hydrocarbon Charge resonance Doubly excited state Luminescent organic diradicals Polyhalogenated trityl radicals |
| Sumario: | The tris(2,4,6-trichlorophenyl)methyl radical (TTM) has inspired the synthesis of several luminescent diradicaloids, providing an extraordinary opportunity to control the nature of the low-lying excited states by fine-tuning the diradical character. However, the photophysical properties of TTM-derived diradicals remain not fully understood yet. Here we present a combined theoretical and experimental investigation to elucidate the origin of their luminescence. The theoretical analysis explores a series of symmetric TTM-derived diradicals with singlet ground state and increasingly longer π-conjugated spacers between radical moieties, focussing on the nature of the lowest excited electronic states governing their photophysics. The study is complemented by a complete spectroscopic characterization of the TTM-TTM diradical, synthesized using a novel, simpler and more efficient procedure exploiting the unique reactivity of TTM. The diradicals feature two novel low-lying excited states, absent in TTM, arising from charge resonance (CR) between the radical units. The lowest CR state is characterized by the H,H→L,L double excitation (DE) and is a dark state for symmetric diradicals. The CR nature explains the blue-shifted emission observed by increasing the distance between the radical centres as seen in TTM-ph-TTM. This insight suggests different design strategies to improve the luminescence properties of TTM-derived diradicals. |
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