Spin‐Correlated Wavelength–Intensity Dual Modulation in Organic Diradicals via Excited‐State Channel Engineering
Year: 2026
Type: article
Abstract: ABSTRACT Luminescent diradicals translate open‐shell spin dynamics into optical readouts, yet their spin‐dependent responses have largely been confined to emission‐intensity changes, while concurrent wavelength modulation remains rare. Here, we introduce a through‐space charge‐transfer (TSCT) strategy in which appending a δ‐carboline donor to a carbazole‐bridged diradical preserves the native through‐bond charge‐transfer (TBCT) pathway while introducing a higher‐energy TSCT‐related emissive channel. At low temperature, δCbCz(TTM) 2 exhibits pronounced magnetoluminescence (MagLum) enhancement together with an approximately 31 nm field‐induced blue shift, while zero‐field warming from 4.5 to 20 K produces an approximately 25 nm blue shift. Temperature‐dependent MagLum measurements show that the additional spectral and intensity changes induced by the magnetic field are rapidly attenuated upon warming, supporting a common spin‐dependent mechanism. The structural analogue αCbCz(TTM) 2 exhibits a similar dual response with a smaller wavelength shift, highlighting the sensitivity of the response to donor topology. Time‐resolved spectroscopy, variable‐temperature EPR, and quantum–chemical calculations support a spin‐correlated photophysical model in which magnetic and thermal perturbations regulate spin‐dependent population redistribution, thereby modulating the relative contributions of TBCT‐ and TSCT‐related emissive channels and producing correlated changes in emission intensity and wavelength. This work establishes through‐space excited‐state channel engineering as a route for extending spin‐correlated luminescence beyond intensity‐only modulation.
DOI: 10.1002/anie.8767910
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W7225573486