Molecular photoswitches that can undergo light-controlled reversible transformations between two distinct isomeric states represent promising candidates for the fabrications of advanced photoswitvchable functional materials including fluorescent probes, optical data storage devices, solar thermal energy and photoresponsive assemblies. However, most currently reported photoswicthes rely on UV light for activation which limits their broad applications. Herein, a series of visible-light responsive arylazopyrazoles molecular switches functionalized with 1,8-naphthalimide (AAP-NI) moiety were designed, synthesized, and studied for their distinct photochromic and fluorescent properties. By introducing different functional groups into the arylazopyrazole unit functionalized with the 1,8-naphthalimide moiety, we obtained fluorecent materails with different emission colors. The photochromic and fluorescence photoswitching behavior of the materials have been systematically investigated by UV-Vis spectroscopy and in the presence of different metal ions in dimethyl formamide solution. The absorption spectra of the fluorophore can be reversible switched by alternating UV and Visible light irradiation. Additionally, the fluorophore shows high selectivity and sensitivity for the detection of Cu²⁺ and Zn²⁺ ions. The fluorophore displayed a dual mode with a turn-on fluorescence and color change response to Cu²⁺ and Zn²⁺ ions. Upon additional of Cu²⁺ and Zn²⁺ ions, the fluorophores displayed remarkable emission enhanced accompanied by the fluorescence color change from orange to yellow green. The effect of the nature of the substituents of the arylazopyrazole structure on the reversible trans-to-cis isomerization processes has also been explored and the results of our findings will be discussed

Jaeden Barr

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