Attachment of a 1,8‐Naphthalimide Moiety to a Conjugated Polythiophene Efficiently Improves the Sensing Abilities of Naphthalimide‐Based Materials

Abstract

A novel polythiophene‐based conjugated polymer bearing 1,8‐naphthalimide‐based pendants is prepared by a two‐step modification of regioregular poly[3‐(6‐bromohexyl)thiophene] involving a nucleophilic substitution reaction of the bromide end‐groups with sodium azide followed by a robust, copper‐catalyzed Huisgen click reaction with a novel 1,8‐naphthalinmide derivative containing an active, N‐substituted propyne group. Both the polymer and the highly luminescent‐active synthesized dye are extensively studied in solution by UV–vis spectroscopy, photoluminescence, NMR, light‐scattering and isothermal titration calorimetry. The materials prepared are considered potential chemosensors for different transition metals, such as Fe2+, Co2+, Ni2+, Cu2+, Zn2+, and Cd2+. Luminescence quenching shows that these materials have a higher sensitivity to Fe2+ than to the other metal ions tested. Moreover, the 1,8‐naphthalimide‐based conjugated polymer is more efficiently quenched by Fe2+ metal ions, at a significantly lower concentration and with a higher binding constant than its parent 1,8‐naphthalimide derivative, thus indicating a high potential for sensor development.

Naphthalimide‐Based Fluorescent Polymers for Molecular Detection

“…A polythiophene‐based conjugated polymer P9‐T bearing 1,8‐naphthalimide based pendants was prepared recently by a two‐step modification of regioregular poly[3‐(6‐bromohexyl)thiophene] (Figure 4b). [ 77 ] The absorption and emission spectra of compound 8 showed significant changes only in the presence of Fe 2+ among other studied metal ions (Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ , and Cd 2+ ) in a chloroform‐methanol (10/1 vol.) mixture.…”

Solid Fluorescence pH Sensors Based on 1,8-Naphthalimide Copolymers Synthesized by UV Curing

“…In that sense, several strategies have been proposed to develop polymers containing naphthalimide moieties, which offer the excellent properties of naphthalimide as a fluorescent sensor and the properties of polymeric materials, such as thermal stability, handleability and mechanical properties. Those materials have found numerous applications for molecular detection in a variety of different areas, including sensor for cations, pH [8] and metal ions [9][10][11]; sensor for anions [12]; cell imaging [13,14]; detection of small molecules [15,16]; and recently have been tested as active components in antibacterial photodynamic therapy [17]. In previous work, photocrosslinked water-swollen acrylic membranes have been functionalized with piperazine naphthalimide derivatives for Hg 2+ and pH detection [18,19].…”

Synthesis and Solvent Dependent Fluorescence of Some Piperidine-Substituted Naphthalimide Derivatives and Consequences for Water Sensing

“…Naphthalimide derivatives are very attractive to be used as photoactive components in colorimetric and fluorometric chemosensors due to the great diversity of their photophysical characteristics. Therefore, the naphthalimide compounds have been applied to detect different metal ions such as Cu 2+ , Zn 2+ , Hg 2+ , Ag + , Fe 3+ , Cr 3+ , or fluoride ion [ 13 , 22 , 23 , 24 , 25 ]. Also, naphthalimide derivatives were explored successfully for monitoring hypochlorous acid and hypochlorite [ 26 , 27 , 28 ].…”