New Fluorescent and Colorimetric Chemosensor for Detection of Cyanide with High Selectivity and Sensitivity in Aqueous Media.

A fluorescent and colorimetric chemosensor for detection of cyanide ion based on a styryl quinoline derivative has been designed and synthesized. The chemosensor (E)-2-(4-mercaptostyryl)quinolin-8-ol L showed high selectivity for detection of cyanide over other anions such as F¯, Cl¯, Br¯, I¯, NO3¯, SCN¯, N3¯, ClO4¯, H2PO4¯, AcO¯, HCO3¯, SO42¯ and HSO4¯in aqueous solution. The chemosensor L displayed an immediate visible and fluorescence changes from nearly colorless to orange and greenish-blue to brick-red upon addition of cyanide ion respectively. It is more likely, these distinct changes can be attributed to hydrogen bonding interaction between phenol group and cyanide anion leading to a 1:1 binding stoichiometry following with deprotonation of phenol group. The detection limit for chemosensor L toward CN¯ was 2.73× 10-8 M. Thus, the chemosensor can be used efficiently and selectively for detection and monitoring of small amounts of cyanide ion in aqueous media.

One-step synthesis of azole- and benzazole-based sulfonamides in aqueous media.

Several benzazoles (benzoxazoles, benzothiazoles, and benzimidazoles) and azoles (1H-1,2,4-triazole-5(4H)-thiones and 1,2,4-oxadiazoles) bearing a sulfonamide moiety were efficiently prepared via the reactions of dimethyl (arylsulfonyl) dithioimidocarbonate derivatives and their 2-aminobenzene precursors, thiosemicarbazides, and amidoximes, respectively, in the presence of K(2)CO(3) as a base in aqueous ethanol (25%) as a green media in moderate to excellent yields.

Approaches to the construction of substituted 4-amino-1H-pyrrol-2(5H)-ones.

Fully substituted 4-aminopyrrolones are easily accessed via simple routes starting from imines, ketones, or α-bromophenyl acetonitriles. Imines were reacted with KCN/NH(4)Cl in aqueous ethanol to produce α-arylamino benzyl cyanides. On the other hand, ketones were transformed to the desired α-amino nitriles using a modified Strecker reaction. Then, α-amino nitrile precursors were allowed to react with a suitable acyl halide to produce the corresponding amides. Further treatment of these amides with ethanolic KOH converted them to highly substituted 4-amino-1H-pyrrol-2(5H)-one derivatives in moderate to excellent yields.

A quinoxaline-based porous organic polymer containing copper nanoparticles CuNPs@Q-POP as a robust nanocatalyst toward C-N coupling reaction.

A novel porous organic polymer (denoted by Q-POP) was successfully fabricated by free-radical copolymerization of allyl-substituted 2,3-di(2-hydroxyphenyl)1,2-dihydroquinoxaline, and divinylbenzene under solvothermal conditions and used as a new platform for immobilization of copper nanoparticles. The CuNPs@Q-POP nanocatalyst was prepared via incorporating of Cu(NO3)2 into the polymeric network, followed by the reduction of Cu2+ ion with hydrazine hydrate. The obtained materials were characterized through FT-IR, XRD, N2 adsorption-desorption isotherms, ICP, TGA, SEM, HR-TEM, EDX, and the single-crystal X-ray crystallography. The results displayed that Q-POP and CuNPs@Q-POP possessed high surface area, hierarchical porosity, and excellent thermal and chemical stability. The as-synthesized catalyst was utilized for the Ullmann C-N coupling reaction of aromatic amines and different aryl halides to prepare various diarylamine derivatives. All types of aryl halides (except aryl fluorides) were screened in the Ullmann C-N coupling reaction with aromatic amines to produce diaryl amines in good to excellent yields (50-98%), and it turned out that aryl iodides have the best results. Besides, due to the strong interactions between CuNPs, N, and O-atoms of quinoxaline moiety existing in the polymeric framework, the copper leaching from the support was not observed. Furthermore, the catalyst was recycled and reused for five consecutive runs without significant activity loss.

A smart low molecular weight gelator for the triple detection of copper (II), mercury (II), and cyanide ions in water resources.

Novel supramolecular gelators based on quinoline-indolin-2-one structure were synthesized. These gelators formed stable organogels in a mixture of DMSO/H2O (1:1). The scanning electron microscopy (SEM), IR and NMR spectroscopies, and rheological measurements were used to study the properties of the gels. Among the synthesized compounds, G2 was chosen as the best gelator and utilized as a naked eye chemosensor for the selective detection of Cu2+ and Hg2+ ions alongside and CN‾ ion as toxic and hazardous materials. The gelator G2 was selectively transformed into a sol state in the presence of Cu2+ ion alongside with a vivid change of color from orange to cherry red. Hg2+ ion showed a notable change in color from orange to brick red, but the gel state remained intact. The detection limit for the gelator G2 toward Cu2+and Hg2+ were 7.25 × 10-6 mol. L-1 and 4.80 × 10-6 mol. L-1 respectively. All the tested anions had no distinct effect on the gel state and/or the color of G2, while, in the presence of CN‾, although the gel state was again unchanged a drastic color change from orange to dark purple was observed. The detection limit for G2 toward CN- was 1.36 × 10-4 mol. L-1. The gelator G2 also operated simultaneously the roles of INH and OR gates in which water, Hg2+, Cu2+ ions are inputs, and the gel state and absorbance around 600 nm (color change) are outputs.

A coumarin based highly sensitive fluorescent chemosensor for selective detection of zinc ion.

A very effective and highly sensitive fluorescent chemosensor, based on 4-hydroxycoumarin skeleton substituted by benzothiazole moiety was synthesized and investigated for the detection of zinc ion. This chemosensor displays highly selective and sensitive fluorescence enhancement to Zn2+ over other metal ions examined in solution and in biological systems. The detection limit for the fluorescent chemosensor 1 toward Zn2+ was 3.58 × 10-8 M. A simple and efficient approach was improved for the synthesis of chemosensor 1 starting from 4-hydroxycoumarin.

Aryliodoazide Synthons: A Different Approach for Diversified Synthesis of 2-Aminothiazole, 1,3-Thiazole, and 1,3-Selenazole Scaffolds.

Several straightforward and practical processes have been established for the construction of 2-aminothiazoles, 1,3-thiazoles and 1,3-selenazoles from aryliodoazides. These strategies successfully proceed with a wide spectrum of substituted thioamides and its derivatives producing the resulting five-membered heterocycles obtained in satisfactory yields. The unique features of these protocols are operational simplicity and highly functional group tolerance, which make them convenient and practical routes for the preparation of various libraries of 2-aminothiazoles, 1,3-thiazoles, and 1,3-selenazoles.

Highly selective fluorescent and colorimetric chemosensor for detection of Hg2+ ion in aqueous media.

A highly efficient and selective fluorescent and colorimetric chemosensor based on naphthothiazole skeleton was synthesized and its colorimetric and fluorescent properties were investigated. The sensor displays a rapid and highly selective colorimetric and fluorescence response toward Hg2+ without interference with other metal ions in CH3CN/H2O mixture (50/50, v/v). The detection limit for the fluorescent chemosensor S1 toward Hg2+ was 3.42×10-8M.

A new isoindoline-based highly selective "turn-on" fluorescent chemodosimeter for detection of mercury ion.

A new isoindoline-based highly efficient turn-on fluorescent chemodosimeter S with a thioamide functionality as a binding site for selective detection of Hg2+ ion has been developed. The chemodosimeter S showed an extreme selectivity for detection of Hg2+ ion among various two and three-valent metal ions in acetonitrile/water (70/30, v/v). It was found that, in the presence of Hg2+ ion the non-fluorescent chemodosimeter S was efficiently and rapidly desulfurized to the corresponding highly fluorescent amide 1. A good linear relationship was shown between the fluorescence intensity and the concentration of Hg2+ within the range of 0-1µM, with a detection limit of 2.03×10-8M.