Optical switching, photophysical, and electrochemical behaviors of pendant triazole‐linked indolylfulgimide polymer

Abstract

Triazole-linked 2-indolylfulgimide polymer has been synthesized and its photochromic switching behavior has been characterized by NMR, IR, GPC, TGA, DSC, and UV-Vis spectroscopy. The synthesized photochromic polymer showed absorption peak maxima at 386 and 510 nm wherein the absorption at 510 nm was attributed to charge transfer from triazole ring nitrogen to carbonyl carbon of fulgimide unit. Fluorescence lifetime studies on exciting at 550 nm reveals triexponential behavior with fluorescence decay around 0.1, 1 and 4.2 ns, which correspond to open (E), closed (C) form of fulgimide and triazole ring, respectively. Whereas exciting at 470 nm evidences biexponential fit with fluorescence decay around 0.1 and 2.2 ns, which corresponds to the closed (C) form and triazole ring, respectively. Fluorescence decay of tria-zole ring was found to be influenced by the excitation wavelength. The cyclic voltammogram of open form of polymer depicts irreversible reductive wave at À1.4 V. On illumination with 360-nm light, the reduction wave of polymer was shifted toward less cathodic wave at À0.9 V; this leads to formation of the closed form of fulgimide unit. V

Functionalized Fulgides and Fluorophore‐Photoswitch Conjugates

“…These groups offer a wide range of binding options to any target molecule, e.g. to polymers [8,9] and dyes. For fluorescence switching purposes, we synthesized and investigated fulgides linked to fluorophores such as anthracene and coumarin via substitution or copper-catalyzed azide-alkyne cycloaddition (CuAAC).…”

Photochromic copolymers containing 3-indolylfulgides/indolylfulgimides: Synthesis and photochemical properties in toluene and as films

“…The copolymers were photochromic, stable at room temperature, and lost less than 10% of their color after cycling back and forth between the open and closed form 100 times. Ramamurthy et al attached 2-indolylfulgimide to methyl methacrylate using click chemistry and then prepared a linear polymer that was photochromic [31]. Kannan et al prepared linear copolymers by copolymerized methyl methacrylate with a pendant 2-indolylfulgimide and methyl methacrylate with pendant azobenzenes [32].…”

Synthesis and Characterization of Photochromic Copolymers Containing 3-Indolylfulgides/Indolylfulgimides

“…40 The monomeric fulgimide with triazole ring prepared via "click chemistry" increased the thermal stability of the polymer. …”