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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]

• We have synthesized a novel compound,5-(1H-pyrrol-2yl)-7, 8, 13, 14-tetrahydrodibenzo [a, i] phenanthridine. • It detects Al3+, Th4+ and picric acid in ACN/Water medium through ratiometric fluorescence. • The limit of detection (LOD) values are 11.37 nM and 12.5 nM and 0.53 nM for Al3+, Th4+ and picric acid respectively. The ratiometric fluorescence sensor of 5-(1H-pyrrol-2yl)-7, 8, 13, 14-tetrahydrodibenzo [a,i]phenanthridine (4a), a ligand with blue emission, was introduced for the quantitative recognition of Al3+ and Th4+ ions and picric acid using absorption and emission spectroscopic techniques. We investigated the unique recognition of Al3+ and Th4+ ions and picric acid by 4a using the studies of UV–vis absorption and fluorescence spectroscopy in acetonitrile as solvent. There was a marked color change from blue to green at 365 nm UV light. High binding constant values (Ka) of 1.175 × 107 M−1 for Al3+ ions and of 3.233 × 106 M−1 for Th4+ ions, 4.3093 × 104 M−1 for picricacid respectively were exhibited by the sensor 4a. The interference studies showed the existence of high selectivity and sensitivity for the probe 4a towards Al3+ and Th4+ ions over other competing cations. Ligand 4a interacted with Al3+ and Th4+ ions to create a 1 : 1 complex, and 1H NMR titration and Job's plot studies confirmed this mechanism further. The sensor 4a had many advantages like low detection limits (LOD) of 38.7 nM and 70.5 nM and 0.53 nM towards Al3+ and Th4+ ions, picricacid and fast reaction. The sensing can be carried out in a wide pH range of 3 to 11. The real time application of 4a was effectively verified by the determination of Al3+ and Th4+ ions and picricacid in paper strips test and also in different water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Design and Synthesis of pyrazolo[4,3-e] pyridine (MPDPP) probe, which employs ICT mechanism. • Very selective towards BF 3 in the presence of other species. • This sensor probe was successfully used for bio-imaging and paper strip application for detection of BF 3. • The lowest limit of detection was obtained for this sensor probe. • The response time study realized the time for detection of BF 3 ion in 10 s. A new pyrazolo[4,3-e] pyridine probe (MPDPP) was designed, synthesized and characterized for detecting BF 3 species in semi-aqueous CH 3 CN-H 2 O (8:2, v/v) solution. Probe MPDPP showed a 33 nm longer wavelength in fluorescence emission after adding BF 3 (from 440 to 473 nm). It was estimated that probe had an analytical limit of detection of 1.6 nM of BF 3. The probe detects BF 3 with good repeatability when alternating between BF 3 and Et 3 N. On the basis of absorbance and fluorescence experiments, NMR titrations, and ESI-MS, a plausible binding mechanism has been proposed. Additionally, the probe has been successfully applied to the bio-imaging of BF 3 in E.Coli and Hela cells and measurement of BF 3 in real water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new and economically viable naphthalimide based "turn-on" fluorescent probe for detection of H 2 S has been designed and synthesised. • Probe NAP-N 3 exhibit very high selectivity and sensitivity towards H 2 S. The obtained limit of detection (LOD) for H 2 S is found to be 1.5 μM. • Probe NAP-N 3 can successfully detect H 2 S levels in wine, beer, and various environmental water samples. • Probe NAP-N 3 was successfully implemented in bioimaging application. The selective detection of hydrogen sulfide (H 2 S) in environmental and living systems has gained substantial attention in recent years. However, the identification of rapid and highly selective probes for the detection of H 2 S remains an elusive goal. This article presents the design and synthesis of a fluorescent "turn-on" probe based on the 1,8-naphthalimide framework (NAM-N 3) to achieve this goal. H 2 S triggered reduction of NAM-N 3 resulted in a remarkable ratiometric absorption enhancement alongside fluorescent "turn-on" response in the green region. The detection properties of NAM-N 3 towards H 2 S were satisfactorily studied through fluorescence, UV–vis, 1H NMR, and mass analysis. The detection response was rapid, and the limit of detection (LOD) was calculated as 1.5 μM. The practical applicability of the probe was tested on various platforms. [ABSTRACT FROM AUTHOR]

A new colorimetric, fluorescent chemosensor 2-(benzo[ d ]thiazol-2-yl)-3-(3-(benzo[ d ]thiazol-2-yl)-4-hydroxyphenyl)acrylonitrile (DBTH) with a D-π-A framework has been developed for the detection of cyanide anion (CN−). DBTH can display a high degree of selectivity and sensitivity towards CN− relative to a wide variety of competing anions. DBTH undergoes a color change from colorless to brown after reaction with CN− because of a strong blue shift in the absorption peak at 353 nm. The interaction between blue-fluorescent DBTH and CN− results in a significant decrease in fluorescence. The nucleophilic addition of CN− is the cause of the optical response of DBTH to CN−. The hypothesized mechanism was supported by 1H NMR titrations, mass spectroscopy, and DFT calculations. The detection limit of the probe is (colorimetrically 8.4 nM and fluorometrically 8.9 nM), which is less than the threshold of 1.9 μM set by the World Health Organization (WHO) for CN− ions in an aqueous solution. DBTH coated test kits were developed for on-site detection of cyanide ion that have the added benefit of being solid-supported chemosensors. [Display omitted] • A new chemosensor (DBTH) for the highly selective and sensitive detection of CN− was developed. • The receptor shows distinct colorimetric and fluorescence "on-off "changes upon the addition of CN−. • The sensing mechanism between the receptor and CN− was given in clear detail. • DBTH had a detection limit of (Colorimetrically 8.4 nM and fluorometrically 8.9 nM) towards CN−. • DBTH- coated test strips were developed for quick detection of CN− ions on-site. [ABSTRACT FROM AUTHOR]