Naphthoquinone-Functionalized Nanoporous Silica: Synthesis, Characterization and Application for Fluorescent Sensing of

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Naphthoquinone-Functionalized Nanoporous Silica: Synthesis, Characterization and Application for Fluorescent Sensing of Dicromate Fatemeh Silakhoria, Alireza Badieia, b, *, and Ghodsi Mohammadi Ziaranic aSchool

of Chemistry, College of Science, University of Tehran, Tehran, Iran Nanobiomedicine Center of Excellence, Nanoscience and Nanotechnology Research Center, University of Tehran, Tehran, Iran c Department of Chemistry, Faculty of Science, Alzahra University, Tehran, Iran *e-mail: [email protected]

b

Received January 27, 2018; revised October 14, 2018; accepted March 17, 2020

Abstract—A naphthoquinone-functionalized hybrid organic-inorganic silica-based fluorescent sensor was designed, synthesized and characterized by X-ray diffraction, N2 adsorption-desorption, thermogravimetric and infrared spectroscopy analysis. Fluorescence properties of the prepared sensor were investigated in the presence of different anions under excitation at 305 nm. The fluorescence emission of the sensor was remarkably quenched after addition of Cr2O72 − . Selectivity of the sensor was studied in the presence of common competing metal ions. The obtained results revealed that the sensor had high selectivity toward Cr2O72 − anion. The linear relationship between the concentration of target anion and the fluorescence intensity was proved by performing a titration experiment. Finally, the detection limit was calculated as 6 × 10–6 M, which demonstrates high sensitivity of the sensor toward Cr2O72 − . Keywords: fluorescent sensor, organic-inorganic silica, nanoporous, Cr2O72 − DOI: 10.1134/S1061934820100135

Chromium is one of the most prevalent elements in the nature. It is widely used in many industries such as mineral processing, pigments, leather tanning and electroplating. Chromium commonly exists as Cr(III) and Cr(VI) which demonstrate remarkably different physiological effects. Although Cr(III) is an essential trace element in human body contributing to maintaining the normal glucose tolerance as well as metabolism of lipids, proteins and fats [1, 2], Cr(IV) acts as a hazardous element which can easily penetrate human cells, severely damage different organs such as liver and kidney, oxidize biological molecules such as DNA and show a toxic carcinogenic effect [3]. Therefore, detection of Cr(VI) is extremely important. Until now, a variety of methods have been suggested for chromium ions detection including ion chromatography [4], electrochemical methods [5], atomic absorption [6] and spectrophotometry [7] which are generally cost and time-consuming, requiring sophisticated equipment and complicated sample pretreatment, lacking sensitivity and selectivity to be used in real samples. In contrast, fluorescent sensors have attracted tremendous attentions due to simplic-

ity, fast response times, low costs, high selectivity and sensitivity [8–13]. There are a few reports for preparation of a fluorescent sensor in dichromate detection. For this purpose, a europium coordination polymer with composition of [EuL(CH3COO)Cl]n

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