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

Jesús L Pablos,Fernando Catalina,Teresa Corrales,Esther Hernández

doi:10.3390/chemosensors10020073

Jesús L Pablos, Fernando Catalina + Show 2 more

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https://doi.org/10.3390/chemosensors10020073

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Abstract

Novel water-swollen photo-crosslinked membranes were obtained by copolymerization of the N-vinylpyrrolidone, butyl acrylate and ethyl methacrylate monomers functionalized with naphthalimide groups, as pH sensitive fluorescence probes. For that purpose, two monomers with pending naphthalimide groups anchored to ethyl methacrylate through alkyl chains with different length, were previously synthesized. The membranes were characterized using different techniques. The pH dependence of absorbance and the corresponding quenching of fluorescence were investigated and related to the structure of naphthalimide substituents linked to the membrane. The new solid sensors exhibited sensitive fluorescence changes at pH < 3, and lower time response was determined for membranes where the sensing group was linked through longer alkyl chain to the polymer matrix. The membranes were solid, thermally stable and easily handled to be applied as sensor materials, and showed a reversible behavior, which is an important feature for further fabrication of an economical on-site tool for the acidity detection in aqueous environments.

Highlights

Novel water-swollen photo-crosslinked membranes were obtained by copolymerization of the N-vinylpyrrolidone, butyl acrylate and ethyl methacrylate monomers functionalized with naphthalimide groups, as pH sensitive fluorescence probes
Two monomers were synthesized with pending naphthalimide group attached to ethyl methacrylate by alkyl chain with different length, 2-hydroxyethyl
Membranes containing naphthalimide derivatives were developed by photopolymerization of a mixture of monomers, N-vinylpyrrolidone (VP), butyl acrylate (BA), ethylene glycol dimethacrylate (EGDMMA) and monomer previously synthesized 3a or 3b, to assess the influence of the alkyl chain length on their properties, Figure 2

Summary

Introduction

Novel water-swollen photo-crosslinked membranes were obtained by copolymerization of the N-vinylpyrrolidone, butyl acrylate and ethyl methacrylate monomers functionalized with naphthalimide groups, as pH sensitive fluorescence probes. Two monomers with pending naphthalimide groups anchored to ethyl methacrylate through alkyl chains with different length, were previously synthesized. The new solid sensors exhibited sensitive fluorescence changes at pH < 3, and lower time response was determined for membranes where the sensing group was linked through longer alkyl chain to the polymer matrix. Despite the many types of naphthalimides synthesized, the design of new fluorescent sensors which exhibit high selectivity and sensitivity fluorescence, low-toxicity and stability are still challenging [3,4]. The use of polymers containing fluorescent structures anchored capable of acting as sensors in the medium are of great interest from an applied point of view, because it contributes to easy reuse, increases the stability along time, and because of the thermal and chemical resistance [7]. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations

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