Photochromic and fluorescence switching behavior of triazole-functionalized fulgimides: Experimental and theoretical study
Khamis Nassor Ally, Melkizedeck Hiiti Tsere, Said Ali Vuai, Azaria Stephano Lameck, Leyla Gundogdu, Mahmut Kose
article (Uluslararası, Hakemli) | Yazar(lar): Khamis Nassor Ally, Melkizedeck Hiiti Tsere, Said Ali Vuai, Azaria Stephano Lameck, Leyla Gundogdu, Mahmut Kose | Yıl: 2026 | Dergi/Kurum: JOURNAL OF LUMINESCENCE | İndeks: WOS.SCI | DOI: 10.1016/j.jlumin.2026.121963 | Anahtar Kelimeler: Photochromism, Fulgide, Fulgimide, T
Integrating photochromism and fluorescence switching within a single molecular platform remains a central challenge in the development of light-regulated functional materials. Here, we report a structure-encoded design strategy based on the direct covalent incorporation of a 1,2,4-triazole unit into the imide framework of fulgimides, yielding three new photoresponsive molecules (4E-6E). Experimentally, all compounds exhibit photochromism based on the interconversion between open and closed forms. This is accompanied by large visiblerange spectral contrast and reversible fluorescence ON/OFF switching under alternating UV and visible light. The open-ring forms are strongly emissive, while photoinduced cyclization produces systematic fluorescence quenching (20-40%) governed by intramolecular energy transfer to the conjugated closed-ring core. Density functional and time-dependent DFT calculations quantitatively reproduce the observed experimental absorption behavior and reveal pronounced pi-delocalization and HOMO-LUMO gap narrowing upon ring closure, establishing clear structure-property relationships. Among the series, compound 6E shows the most favorable electronic and optical characteristics. These results identify triazole-imide coupling as a generalizable molecular engineering route for multifunctional organic photo-switches and advance their potential for optical memory, sensing, and adaptive photonic applications.