Restricting intramolecular motion converts non-fluorescent semicroconaine dyes into turn-on aggregation-induced emission probes
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Article in Periodical |
| Magazine / Source | Materials Chemistry Frontiers |
| MU Faculty or unit | |
| Citation | |
| web | https://pubs.rsc.org/en/content/articlelanding/2025/qm/d5qm00030k |
| Doi | http://dx.doi.org/10.1039/d5qm00030k |
| Keywords | FLUORESCENT-PROBES; ORGANIC-DYES; FLUOROPHORES; SYSTEMS; DESIGN; LENGTH |
| Attached files | |
| Description | Bucking the trend of all other polymethines, semicroconaines are virtually non-fluorescent (Phi(f) < 0.1%) dyes. But their fluorescence could be increased through external physicochemical factors, thereby converting them into turn-on fluorescent probes. To test this hypothesis, we analyzed excited-state dynamics of a small library of semicroconaines bearing various auxochrome substituents to determine how they lose excited-state energy. Using a combined experimental/quantum-chemical approach, we found that isomerization of their methine bridge leads to non-radiative S-1-S-0 relaxation through a conical intersection. This relaxation pattern was consistently identified in semicroconaines with various auxochrome substituents (-F, -I, -OCH3, -SO3H and -NO2). Just as consistently, their fluorescence in solution significantly increased when increasing solvent viscosity and inducing complexation with two macromolecules, namely glycoluril dimer and DNA. Therefore, semicroconaine dyes display turn-on aggregation-induced emission, a mechanism that may be exploited for macromolecular sensing under physiological and pathological conditions. |
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