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The solvothermal method of producing spherically shaped and highly fluorescent tiny (∼3 nm) nitrogen-doped carbon quantum dots (NCQDs) with high quantum yield (43%) from Ixora coccinea flowers and o-phenylenediamine has been approached sustainably. Since these NCQDs exhibit excitation-dependent fluorescence activity, they were used to detect the Fe3+ ion selectively in real-time in human blood serum, because it is a component of human blood. The limit of detection (LOD) of the NCQDs was found to be 60 nM. We also synthesized palladium nanoparticles utilizing the NCQDs without additional reducing or stabilizing agents because these quantum dots serve as both. Numerous characterization techniques were used to characterize the nanoparticles, and all the characterizations showed the presence of NCQDs, which stabilize the nanoparticles. Palladium nanoparticles' small size (4 nm) and large surface area (35.77 m2 g−1) enable them to exhibit strong catalytic activity in Suzuki–Miyaura coupling and cyanation processes. It is obvious that synthetic palladium nanoparticles and NCQDs have a variety of uses in the fields of catalysis and sensing respectively. [ABSTRACT FROM AUTHOR]

In this work, we synthesized diethylamino substituted pyrazolo imine (3) fluorescent probe for recognition of Hg2+ion.The sensor probe 3 can detect Hg2+ by colorimetric method, and there is a 10‐fold enhancement in fluorescence response. When the fluorescent probe bound with Hg2+ ion, turn‐on fluorescence was observed via the coordination. Probe 3 has an excellent selectivity toward Hg2+ in the CH3CN/H2O (8:2, v/v) solution with low limit of detection and high binding association constant of 551 parts per billion (ppb) and 6.6067 × 106 m−1 for 3+Hg2+, respectively. Furthermore, the formation of 3+Hg2+ complex with 1:1 binding mode was evidenced by Job's plot, 1H NMR spectroscopy and Mass analysis. In addition, probe 3 is a feasible option to detect Hg2+ in various sources of water samples. Bio‐imaging experiments have demonstrated that probe 3 can be used to monitor Hg2+ in Escherichia coli bacterial cell. The sensor 3 was also used for paper strip application to detect Hg2+ ion. [ABSTRACT FROM AUTHOR]

Heavy metals emanate from natural and man-made sources, such as agricultural chemicals including fertilisers and pesticides, medical waste, and chemicals released from industries. Detection and monitoring toxic metal ions is one of the challenges confronting scientists in biological, environmental, and chemical systems. This study describes the design and synthesis of a new imidazole-based fluorescent and colourimetric chemosensor (DPICDT) for highly selective sensing of Hg 2+ and Cu 2+ ions in aqueous acetonitrile medium. The probe was synthesised by coupling benzil and substituted aldehyde using ethanolic ammonium acetate. The structure of DPICDT was confirmed via IR spectra, NMR, and HR-MS spectra. The DPICDT probe displayed a rapid naked-eye response towards Cu 2+ ions from colourless to red-purple and significant fluorescence quenching response towards Hg 2+ over other competitive metal ions in both solution and solid support. The binding modes of DPICDT with Cu 2+ and Hg 2+ ions were found to be at a 1 : 1 ratio as determined using Job plot, ESI HR-MS, and the sensing mechanism was evolved by 1 H NMR titrations, HR-MS spectra, and DFT calculations. The lower detection limit was 15.1 nM for Cu 2+ , eventually far less than the World Health Organization guideline for drinking water (Cu 2+ - 31.5 μM) and 1.17 μM for Hg 2+ (permissible concentration 2 ppb). Promisingly, the tissue paper-based DPICDT test strips and silica-supported DPICDT were developed and demonstrated for on-site application without resorting to expensive instruments., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this work, we synthesized diethylamino substituted pyrazolo imine (3) fluorescent probe for recognition of Hg 2+ ion.The sensor probe 3 can detect Hg 2+ by colorimetric method, and there is a 10-fold enhancement in fluorescence response. When the fluorescent probe bound with Hg 2+ ion, turn-on fluorescence was observed via the coordination. Probe 3 has an excellent selectivity toward Hg 2+ in the CH 3 CN/H 2 O (8:2, v/v) solution with low limit of detection and high binding association constant of 551 parts per billion (ppb) and 6.6067 × 10 6  m -1 for 3+Hg 2+ , respectively. Furthermore, the formation of 3+Hg 2+ complex with 1:1 binding mode was evidenced by Job's plot, 1 H NMR spectroscopy and Mass analysis. In addition, probe 3 is a feasible option to detect Hg 2+ in various sources of water samples. Bio-imaging experiments have demonstrated that probe 3 can be used to monitor Hg 2+ in Escherichia coli bacterial cell. The sensor 3 was also used for paper strip application to detect Hg 2+ ion., (© 2021 American Society for Photobiology.)