[reaction: see text] A new thioamide derivative of 8-hydroxyquinoline-benzothiazole was prepared, and its fluorogenic chemodosimetric behaviors toward transition-metal ions were investigated. The thioamide derivative showed highly Hg2+-selective fluorescence enhancing properties (167-fold) in 30% aqueous acetonitrile solution. The selective and sensitive signaling behaviors were found to originate from the Hg2+ ion induced transformation of the very weak fluorescent thioamide derivative into a highly fluorescent amide analogue.

A series of mono-, di-, and triphosphoniumsubstituted triarylboranes, [Mes 2 BAr P ]I ([2]I), [MesBAr P 2 ]I 2 ([3]I 2 ), and [BAr P 3 ]I 3 ([4]I 3 ) (Ar P = 4-(MePh 2 P)-2,6-Me 2 -C 6 H 2 ), were prepared from the corresponding neutral boranes 2a−4a. The crystal structure of [4]I 3 determined by X-ray diffraction study reveals peripheral decoration of aryl groups with phosphonium moieties. The anion affinity of the cationic boranes for fluoride and cyanide ions was investigated by UV−vis absorption titrations in aqueous solution. The triarylboranes, [2]I−[4]I 3 bind both fluoride and cyanide ions in a DMSO/H 2 O (7:3 v/v) mixture with high binding constants (K). Comparison of the K values of triarylboranes for fluoride reveals that fluorophilicity increases with the increasing number of phosphonium moieties: [2] + (K = 2.3 × 10 1 M −1 ) < [3] 2+ (3.6 × 10 5 M −1 ) < [4] 3+ (1.0 × 10 7 M −1 ). A similar trend is also observed in the cyanide binding, with K values that are greater by 2−4 orders of magnitude than those in the fluoride binding. These results indicate an apparent additive effect of multiple phosphonium substitutions on the Lewis acidity enhancement of triarylboranes. The triphosphonium borane [4]Cl 3 , a water-soluble form of [4]I 3 , was further utilized in evaluating the anion affinity in water. While [4] 3+ is shown to hardly bind fluoride in buffered water at pH 7, it binds cyanide with a high binding constant (1.7 × 10 7 M −1 ).

The o-carborane-triarylborane dyad shows high fluoride ion affinity through the trigonal-planar boron center while degradation to nido-carborane leads to a turn-on fluorescence response toward fluoride.

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A new podand-type dioxaoctanediamide-based chemosensor having two pyrene moieties was prepared, and its fluoroionophoric behaviors toward transition-metal ions were investigated. Pyrene-appended dioxaoctanediamide 1 showed a selective fluorescence quenching toward Hg2+ ions over other transition-metal ions in an aqueous methanol solution. Unique responses in pyrene monomer and excimer emissions allowed selective ratiometric determination of Hg2+ ions in aqueous environments, and the detection limit was found to be 1.6 x 10(-6) M. [structure: see text]

To better understand critical aspects of diarrhetic shellfish poisoning (DSP) occurrence in a chief producing region of bivalves in Korea, the geographical and annual variation of DSP toxins and other lipophilic toxins in mussels (Mytilus galloprovincialis) and oysters (Crassostrea gigas) were investigated by liquid chromatography-tandem mass spectrometry in an area on the south coast of Korea from 2007 to 2009. The total lipophilic shellfish toxin (LST) levels in bivalves showed geographical and annual variations. LSTs were detected mostly in the hepatopancreas of mussels from Jinhae Bay throughout the entire year, except in November and December of 2007, but were almost undetectable in all samples during the entire year in 2009. The peak DSP toxin (okadaic acid plus dinophysistoxin 1) levels in the hepatopancreas of mussels from Jinhae Bay and the Tongyeong region were 945.3 and 37.6 ng/g, respectively. The DSP toxin content was about 10 times higher in mussels than in oysters collected from the same region. The major toxins in bivalves were okadaic acid and dinophysistoxin 1; however, pectenotoxin 2 or yessotoxin was occasionally detected as a major component. The results of a quantitative analysis of phytoplankton showed that Dinophysis acuminata was the most probable source of the LSTs, with the exception of yessotoxin. When the highest DSP toxin level was measured (945.3 ng/g in the hepatopancreas of mussels from Jinhae Bay), the toxin concentration in whole mussel tissue was calculated to be 114.0 ng/g. The calculated highest DSP toxin level in whole oyster tissue from both regions was 15.0 ng/g. The calculated maximum toxicities in whole mussel and oyster tissues were lower than the regulatory limit (160 to 200 ng/g) in Korea, the European Union, and the United States. Korean oysters (242 samples) and mussels (214 samples) were thus deemed safe for consumption. But because such variation was detected in a relatively small area of the coast, it is possible that at some locations or during a specific period LST levels could exceed the standard and a few consumers could be at risk of experiencing DSP.

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