Synthesis and photophysical properties of extended π conjugated naphthalimides

A series of π conjugated naphthalimide derivatives having an imide group as an acceptor conjugated with a methoxy arylethynyl or a methoxyphenyl triazole as a donor were prepared by Sonogashira coupling or "click" chemistry. Their photophysical properties were investigated by steady state and time resolved fluorescence spectroscopy and modelled by TD-DFT calculations. Compound Naphth-AlkyneOMe has a high fluorescence quantum yield and displays efficient photoinduced charge transfer in solution as well as in the powder state. Compound Naphth-TriazoleOMe exhibits a very high Stokes shift and its fluorescence quantum yield is low, which can be rationalized by theoretical calculations.

N-(3-Imidazolyl)propyl dansylamide as a selective Hg(2+) sensor in aqueous media through electron transfer

N-Imidazolylpropyl dansylamide 1 was synthesized for the sensing of metal ions and found to be selective and sensitive toward Hg(2+) ions in a PBS-EtOH (1:4, pH=7.4) solution. The sensing ability of probe 1 was examined by UV-Vis, fluorescence, and (1)H NMR spectroscopy. The sensing of Hg(2+) exhibited a quenching of emission band at λmax=515 nm of probe 1, which was associated with quenching of green fluorescence emission under 365 nm illumination. Probe 1 showed a good association constant with Hg(2+) (Ka=6.48×10(4) M(-1)) with a stoichiometry of 1:1 in PBS-EtOH (1:4, pH=7.4) having the lowest detection limit of 1 μM for Hg(2+); on the other hand, probe 2, which has no imidazole moiety, was not able to detect any metal ion. In the case of probe 1, electrons on the imidazole nitrogen are available for electron transfer (ET), which was responsible for its green emission band that was quenched on addition of Hg(2+); this clearly indicates that these electrons were used for the formation of a coordinate bond with Hg(2+) and that ET was switched off.

Ag-mediated cascade decarboxylative coupling and annulation: a convenient route to 2-phosphinobenzo[b]phosphole oxides

Structurally sophisticated 2-phosphinobenzo[b]phosphole oxide frameworks have been conveniently constructed by cascade decarboxylative coupling and annulation reactions.

Synthesis of ovalbumin-stabilized highly fluorescent gold nanoclusters and their application as an Hg2+ sensor

Highly fluorescent Au nanoclusters were synthesized using ovalbumin (OVA) as a template. The application of the nanoclusters for the detection of mercury ions was also achieved.

Ultra-sensitive and selective Hg2+ chemosensors derived from substituted 8-hydroxyquinoline analogues

A mercury concentration of 15 ppt can be selectively detected, in aqueous medium, thanks to a thiophosphinatylated 8-hydroxyquinoline sensor.

Highly luminescent near-infrared-emitting gold nanoclusters with further natural etching: photoluminescence and Hg2+ detection

Highly luminescent near-infrared (NIR)-emitting gold nanoclusters (Au NCs) protected by glutathione with ultra-small size were prepared at high temperature following with a further natural etching at room temperature. The optical and surface properties of Au NCs were monitored by ultraviolet-visible and photoluminescence (PL) spectra, high-resolution transmission electron microscopy, and electrospray ionization mass spectrometry. The diameter of the etched Au NCs was reduced to approximately 1.35 nm with 30 % PL quantum yield. Interestingly, the PL of Au NCs was decreased obviously by the addition of Hg2+ and increased by the addition of Pb2+ at certain concentration. Our preliminary results illustrated that the highly luminescent NIR-emitting Au NCs would be an alternative probe for the detection of heavy metal ions in water and environmental monitoring.

Highly selective fluorescent sensors for Hg(2+) based on bovine serum albumin-capped gold nanoclusters

In this paper, we report a new homogeneous assay for rapid, highly selective and sensitive detection of Hg(2+) in aqueous solution based on the induced photoluminescence (PL) quenching of BSA-modified gold nanoclusters (BSA-Au NCs). There was a linear correlation between the expression (I(0)- I)/I(0) and the concentrations of Hg(2+) over the ranges of 0.4-43.2 microM, and the corresponding limit of detection (LOD) was 80 nM. The relative standard deviation of 5 replicate measurements was 1.4% for 1.0 x 10(-5) mol L(-1) Hg(2+). Moreover, this method has excellent selectivity over metal ions and anions. The feasibility of the BSA-Au NCs sensor for Hg(2+) in different aqueous samples was demonstrated with satisfactory results. Moreover, the possible sensing Hg(2+) mechanism was also discussed.