Unpredicted Concentration-Dependent Sensory Properties of Pyrene-Containing NBN-Doped Polycyclic Aromatic Hydrocarbons

Pyrene molecules containing NBN-doped polycyclic aromatic hydrocarbons (PAHs) have been synthesized by a simple and efficient intermolecular dehydration reaction between 1-pyrenylboronic acid and aromatic diamine. Pyrene-B (o-phenylenediamine) with a five-membered NBN ring and pyrene-B (1,8-diaminonaphthalene) with a six-membered NBN ring show differing luminescence. Pyrene-B (o-phenylenediamine) shows concentration-dependent luminescence and enhanced emission after grinding at solid state. Pyrene-B (1,8-diaminonaphthalene) exhibits a turn-on type luminescence upon fluoride ion addition at lower concentration, as well as concentration-dependent stability. Further potential applications of Pyrene-B (o-phenylenediamine) on artificial light-harvesting film were demonstrated by using commercial NiR dye as acceptor.

Effects of Nanohydroxyapatite Incorporation into Glass Ionomer Cement (GIC)

Glass ionomer cement (GIC) or polyalkenoate cement is a water-based cement that is commonly used in clinical dentistry procedures as a restorative material. It exhibits great properties such as fluoride-ion release, good biocompatibility, ease of use and great osteoconductive properties. However, GIC’s low mechanical properties have become a major drawback, limiting the cement’s usage, especially in high stress-bearing areas. Nanohydroxyapatite, which is a biologically active phosphate ceramic, is added as a specific filler into glass ionomer cement to improve its properties. In this review, it is shown that incorporating hydroxyapatite nanoparticles (nHA) into GIC has been proven to exhibit better physical properties, such as increasing the compressive strength and fracture toughness. It has also been shown that the addition of nanohydroxyapatite into GIC reduces cytotoxicity and microleakage, whilst heightening its fluoride ion release and antibacterial properties. This review aims to provide a brief overview of the recent studies elucidating their recommendations which are linked to the benefits of incorporating hydroxyapatite nanoparticles into glass ionomer cement.

Fabrication of In(III)-alizarin red S complex trap for efficient detection of fluoride ion in aqueous environs

The work discusses about the synthesis of indium-alizarin red S complex followed by its application toward the sensing of F¯ ion. At first, the interaction between indium and alizarin red S dye was studied at three different pH medium, pH 4, 7 and 9, of which pH 7 gave the best result. The indium-alizarin red S complex so obtained was then utilized for the ratiometric sensing of fluoride ion using absorption spectroscopy with variation of temperature. The lowest limit of detection (0.040 mM) was obtained at 313 K. The mechanism for the sensing of F¯ ion was then investigated using isothermal titration calorimetry. The endothermic nature of the interaction between F¯ ion with indium-alizarin red S complex shows temperature dependence on the sensing experiment. At the end, the utility of the technique toward natural sample was also examined. The present work reports a simple, rapid and efficient detection of fluoride anion in environmental water samples.