engleski

Application of Fluorescent Benzimidazole Derivatives in Functional Materials: a Mercury (II) Sensitive Chemodosimeter

Novel functional materials based on benzimidazole derivates are a growing area of research. The multifunctionality of benzimidazole derivatives can be exploited in heteroaromatic molecular systems for optoelectronics and non-linear optics (NLO), photovoltaics, and in sensing and bioimaging. The structure-related properties of the benzimidazole unit, such as its similarity to naturally occurring nucleotides, electron accepting ability, π-bridging or chromogenic pH sensitivity/switching make it an exceptional structural candidate for development of multifunctional molecular devices and materials [1]. Here we present a novel sensing membrane based on plasticised PVC as a new optical system for mercury (II) detection. The optical system behaves like an irreversible chemical sensor - a chemodosimeter - and could thus be used as a single-shot test for the rapid and economic detection of mercury. The benzimidazole derivative is responsible for the formation of the analytical signal, whilst a lipophilic borate anion provides the sensing part of the optode, and is responsible for the detection of mercury ions in the sample. The detection mechanism is based on the fluorescent response of the benzimidazole derivative, and the formation of an ionic pair with the lipophilic anionic salt, tetrachlorophenyl borate [2, 3]. Borate salt decomposes in the presence of mercury ions, and at the same time, the ionic pair comprising the Fluorophore+Receptor− disintegrates. As a result, the benzimidazole fluorophore deprotonates in order to preserve overall electroneutrality of the membrane, simultaneously changing its photophysical properties. The mercury (II) sensitive dosimeter optodes were prepared by spin coating thin polymer films onto transparent carriers, immobilising the fluorophore and anionic borate salt in a plasticised PVC matrix. The mechanism of sensing activity, linear range, response time, and the stability of this novel functional material is characterised by UV-visible absorption and fluorescence spectrophotometry.

fluorescent sensor ; functional material ; chemodosimeter ; mercury

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