Annada C. Maity

ESIPT based Hg2+ and fluoride chemosensor for sensitive and selective ‘turn on’ red signal and cell imaging

An excited state intramolecular proton transfer (ESIPT) enabled fluorescent sensor phenanthroline diimino phenol (PDP) for Hg2+ has been designed and synthesized. PDP acts as a dual sensor and selectively detects only Hg2+ in mixed aqueous medium and fluoride in acetonitrile medium over other competing metal ions and anions. The binding of PDP with Hg2+ is supported by DFT. The ESIPT phenomenon in PDP is favored in the presence of Hg2+, which is rarely reported, along with an intense red fluorescence suppressing other competing metal ions. Among different anionic analytes, only fluoride shows a visually detectable exciting color change from pale yellow to pink with almost similar emission characteristics. PDP also demonstrates its importance in the fluorescent imaging of Hg2+ ions in human cancer cells.

Simple and Efficient Synthesis of 2,7-Difunctionalized-1,8-Naphthyridines

The syntheses in good yields of some new difunctionalized 1,8-naphthyridines 4, 6, 8 and 9 and a novel triethylene glycol ether-linked dinaphthyridine, 10a, along with the mononaphthyridine-linked ether alcohol 10b are described. An improved and milder method for the synthesis of 2,7-diamino-1,8-naphthyridine (14) is also reported.

A FRET-based rhodamine–benzimidazole conjugate as a Cu2+-selective colorimetric and ratiometric fluorescence probe that functions as a cytoplasm marker

On the basis of fluorescence resonance energy transfer (FRET) from benzimidazole to a rhodamine moiety, a rhodamine–benzimidazole conjugate (RBC) ratiometric fluorescent probe has been designed and synthesized. The RBC selectively binds to Cu2+, showing visually observable changes in absorption and emission behavior, and demonstrates an effective intracellular Cu2+ imaging ability, allowing it to function as a cytoplasm marker.

Advanced reagent for thionation: Rapid synthesis of primary thioamides from nitriles at room temperature

A series of aliphatic, aromatic and heterocyclic nitriles is thionated to give the corresponding thioamides in excellent yield using a newly developed reagent system of phosphorus pentasulfide and sodium sulfite or sodium dithionite at room temperature in a very short time (5–25 minutes). The microwave procedure of the reactions also is reported to afford the same products.

Triselenium Dicyanide (TSD) as a New Cyanation Reagent: Synthesis of Cyano Pterins and Quinoxalines Along with Library of Cyano N-Heterocyclic Compounds

Abstract Triselenium dicynide (TSD) has been reported for the first time to be a novel cyanation reagent for the microwave-assisted one-pot synthesis of a series of various types of cyano N-heterocycles such as pterin, deazapterin, quinoxaline, naphthyridine, and pyridine in good yields.

2-(Pyrene-1-yl)-1,3-dithiane

In the title compound, C20H16S2, the pyrene ring is planar [maximum deviation 0.0144 (15) Å] and the dithiane ring adopts a chair conformation. The crystal packing is stabilized by C—H⋯π interactions. An intramolecular C—H⋯S hydrogen bond generates an S(5) ring motif.

2-(1,3-Dithian-2-yl)-1,3-dithiane-2-carbaldehyde

The asymmetric unit of the title compound, C9H14OS4, comprises two crystallographically independent molecules with similar conformations. In each molecule, an intramolecular C—H⋯O hydrogen bond generates a six-membered ring, producing an S(6) ring motif. All of the six-membered dithiacyclohexane rings adopt chair conformations. The crystal structure is stabilized by four intermolecular C—H⋯O and one C—H⋯S interaction.

Bis(2,1,3-benzoselenadiazole-κN)dichloridozinc(II)

In the title complex, [ZnCl2(C6H4N2Se)2], the ZnII center is tetracoordinated by a Cl2N2 donor set in a distorted tetrahedral geometry. Some of the distortion from the ideal tetrahedral geometry might be ascribed to two agostic Z⋯H interactions The two 2,1,3-benzoselenadiazole ligands are each essentially planar and form a dihedral angle of 35.06 (9)°. An interesting feature of the crystal packing is the observation of short intermolecular contacts between Se and Se, Se and N, and N and N atoms. These arise as a result of three-center bridging of adjacent molecules into chains along the b axis. The crystal structure is stablilized by π–π interactions [minimum centroid–centroid distance = 3.5694 (18) Å].

Bis(2,1,3-benzoselenadiazole-κN)dibromidocopper(II)

In the title complex, [CuBr2(C6H4N2Se)2], the CuII ion is tetracoordinated by two bromide anions and two N atoms in a distorted square-planar geometry. The two essentially planar 2,1,3-benzoselenadiazole ligands [maximum deviations = 0.012 (2) and 0.030 (2) Å] are approximately coplanar [dihedral angle = 6.14 (6)°]. In the crystal, short intermolecular Se⋯Br, Se⋯N and N⋯N interactions are observed. These short interactions and intermolecular C—H⋯Br hydrogen bonds link the complex molecules into two-dimensional arrays parallel to the ac plane.

1,10-Phenanthroline–dithio­oxamide (2/1)

The asymmetric unit of the title compound, C12H8N2·0.5C2H4N2S2, contains one 1,10-phenanthroline molecule and a half-molecule of dithiooxamide, which lies across a crystallographic inversion center. The 1,10-phenanthroline unit is not strictly planar, with dihedral angles between the central benzene ring and the pyridine rings of 1.42 (10) and 1.40 (10)°. In the crystal structure, two 1,10-phenanthroline molecules are linked together by one dithiooxamide via intermolecular N—H⋯N hydrogen bonds.