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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]

A new family of extended π‐conjugated dihydrobenzopyrazoloquinoline (DBPQ) and dihydroindenopyrazolopyridine (DIPP) molecules were synthesized, and their photophysical and electrochemical properties were studied. The DBPQ derivatives showed significantly higher molar absorption coefficients, and their absorption and emission wavelengths were red‐shifted with respect to those of the corresponding DIPP derivatives in chloroform solution. Dyes with no substitution and methoxy, nitro, and fluoro‐substituted derivatives showed poor dependence on solvent polarity. At the same time, DBPQ and DIPP derivatives with dimethylamino groups exhibited strong solvatochromism in the emission spectra. Due to the presence of a vinyl link with a cylindrical π‐cloud on the donor (dimethylamino group) molecule, they showed efficient positive solvatochromism with high quantum yields on increasing solvent polarity from non‐polar to polar solvents. Aggregation‐induced emission (AIE) properties were also investigated. AIE studies show that the emission of DBPQ and DIPP derivatives in the presence of THF/H2O mixture increased due to aggregation. However, DBPQ and DIPP derivatives were still strongly emissive in the solid state. Dimethylamino substituted derivatives exhibited acidochromism, which was caused by the addition of TFA and pTsA leading to prominent red‐shifts in the emission spectra owing to the protonation at the pyridine segment. A new family of extended π‐conjugated dihydrobenzopyrazoloquinoline (DBPQ) and dihydroindenopyrazolopyridine (DIPP) molecules were synthesized, and their optical and electrochemical properties were studied. Aggregation‐induced emission (AIE) properties were also investigated. [ABSTRACT FROM AUTHOR]