An N-Heterocyclic Carbene System Integrating Molecular Switching Functionality and Bright Luminescence

Abstract

The field of chemistry, across its various subdisciplines, has been significantly enriched by advances in understanding carbon intermediates since the 19th century. Among them, carbenes have evolved from transient intermediates to versatile molecular tools, yet integrating luminescence and stimuli-responsiveness in a single system remains a challenge. We report a lithium-bridged carbene-amide hybrid achieves this bifunctional integration. This architecture exhibits intense fluorescence (luminescence efficiency: Φ_PL = 85%) and undergoes reversible two-electron cycling among carbene-amido, radical intermediate, and delocalized carbocation states via stepwise single-electron transfers, as demonstrated by crystallographic, spectroscopic, and computational analyses. The asymmetric redox pathway involves N-centered radical formation during oxidation but bypasses this intermediate during reduction, enabling dynamic interconversion. This redox transformation facilitates the direct and reversible conversion between the carbene and carbocation species in a single mechanistic step. Structural studies reveal lithium coordination geometry and charge delocalization underpinning stability. Bridging exciton engineering and dynamic materials science, the work opens avenues for smart molecular technologies in precision synthesis and optoelectronics.

Keywords

N-Heterocyclic carbene / Molecular switch / Multifunctional molecule / Luminescence / Carbene-amide complex / Li-NHC complex / Organometallic / Carbocation

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2025 SIOC, CAS, Shanghai, & WILEY-VCH GmbH