A smartphone sensing fluorescent detection of mercury ion based on silicon quantum dots in environment water

Mercury ion (Hg2+) pose a significant hazard to the natural environment. Conventional techniques like Inductively coupled plasma mass spectrometry, X-ray absorption spectroscopy, among others, pose some disadvantages as they demand a lot of money, need trained employees, and cannot provide on-site detection in real-time. A smartphone sensing technique based on silicon quantum dots (Si-QDs) was presented to detect Hg2+ in the environment without the usage of sophisticated equipment. Meanwhile, the technology was built by utilizing a smartphone to capture gray values of fluorescent images of the Si-QDs-Hg2+ system. Microwave-assisted Si-QDs with tiny particle size, high fluorescence, and good optical stability were created. The fluorescence of the Si-QDs was gradually quenched by raising the Hg2+ concentration from 0.5 μmol/L to 5.0 μmol/L for fluorescent detection with a detection limit of 28 nmol/L. The 94.8-97.1 % recovery demonstrated the viability of the Si-QDs approach for detecting Hg2+. Meanwhile, a smartphone sensing strategy was built by recording the gray value of the fluorescent images of the Si-QDs-Hg2+ systems using a smartphone, and the detection limit of the established approach was 3 nmol/L. The accuracy and reliability of the smartphone strategy were verified with the recovery rates of 80.3-92.5 % in tap water and 87.6-109 % in river water. Electron transfer quenching mechanism between Si-QDs and Hg2+ was evidenced by ultraviolet-visible spectroscopy, fluorescent decay curves, cyclic voltammetry, and Zeta potential. Finally, the suggested approach was used to detect Hg2+ in water samples from various environments.

A series of phenanthroline-imine compounds: Computational, OLED properties and fluorimetric sensing of nitroaromatic compounds

In this study, Schiff base compounds (1-5) were synthesized by the reaction of 5-amino-1,10-phenanthroline with various aldehydes. The molecular structures of the synthesized compounds were characterized by FT-IR, ¹H/¹³C NMR and mass spectroscopic methods. Single crystals of 1 were obtained and their molecular structures in crystalline form were determined by single crystal X-ray diffraction study. The sensor properties of the synthesized compounds against nitroaromatic compounds [nitrobenzene (NB), 4-nitrophenol (NP), 2,4-dintrophenol (DNP) and 1,3,5-trinitrophenol (TNP)] were investigated by fluorescence spectroscopy. Compound 3 have highest sensitivity for the sensing of 1,3,5-trinitrophenol (TNP) (Ksv: 4.63 × 10⁴ M^-1) with LOD of 4.01 µM while compound 5 showed the highest sensitivity for 2,4-dinitrophenol (DNP) (Ksv: 5.71 × 10⁴ M^-1) with LOD of 4.75 µM. In addition, the structural parameters (bond angles/lengths), contour diagrams of HOMO/LUMO molecular orbitals, molecular electrostatic potential (MEP) maps, non-linear optical (NLO) and OLED properties were investigated by computational studies. According to the HOMO and LUMO energies, the NLO property of the molecule (5) is higher than both other molecules and the reference substance urea.

Synthesis and Properties of D–π–A Structural Imidazole-Triphenylamine Derivatives

Four novel D-π-A structural 1-aryl-2-[4-(N,N-diphenyl)phenyl]-4,5-diphenyl-1H-imidazoles have been synthesised. Their synthesis, thermal stability, optical properties and electrochemical behaviour have also been investigated. These compounds exhibit increased thermal stability, blue emissions and intramolecular charge transfer. The HOMO and LUMO energy levels of these compounds were calculated from electrochemical measurements.