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    A BODIPY decorated multiple mode reusable paper-based colorimetric and fluorometric pH sensor
    (Elsevier, 2022) Ozturk, Dilek; Omeroglu, Ipek; Gol, Cem; Durmus, Mahmut
    In this study, two difluoroboradiazaindacene (BODIPY) compounds bearing diethylaminostyryl groups were synthesized in order to establish colorimetric and fluorometric paper-based pH sensors. The structures of these novel BODIPY compounds were identified by NMR (H-1, C-13, B-11, and F-19), elemental analysis, MALDI-TOF, FT-IR, UV-vis and fluorescence spectroscopies as well as single-crystal X-Ray data. The DFT study was also per-formed to optimize of these two novel BODIPY structures. Electrochemical measurements were applied to estimate their redox potentials. Photophysical properties such as fluorescence quantum yield and lifetimes were investigated to determine the effect of acid addition in both DMSO and 1,4-dioxane solutions of the studied BODIPY derivatives. Also, pKa values of the synthesized compounds (1a and 1b) were determined from absorbance and fluorescence measurements by acid titration studies. The paper-based pH sensor behavior of these BODIPY derivatives was investigated and their performances were determined on the lemon juice samples as a real sample analysis. A simple, cost-effective, rapid, portable, colorimetric, and fluorometric paper-based BODIPY sensing platform was developed in this study for the detection of the variety of pH changes in lemon juice.
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    One-pot hydrothermal conversion of different residues to value-added chemicals using new acidic carbonaceous catalyst
    (Elsevier Sci Ltd, 2019) Özsel Kaya, Burçak; Ozturk, Dilek; Niş, Berna
    The direct hydrothermal conversion of waste biomass to 5-hydroxymethyl furfural (5-HMF) and levulinic acid was studied here in the presence of new biomass-derived sulfonated carbonaceous solid acid catalysts. Different cheap and waste lignocellulosic/cellulosic biomass materials (wheat straw, corn straw, cotton linter and industrial textile fluff) were used as feedstock to prepare bio-based chemicals in an eco-friendly and economical process. The yields of products were improved by optimization of reaction temperature, reaction time and catalyst type for various types of biomass. Under the optimum reaction conditions BT300S sulfonated solid acid carbonaceous catalyst has exhibited higher activity compared to commercial Amberlyst 15 thus 403.7 ppm 5-HMF (16.2 mg 5-HMF/g biomass) and 1624.8 ppm LA (65.6 mg LA/g biomass) have been generated from corn straw biomass in aqueous media at 200 degrees C in 1 h.