Sibaprasad 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.

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.

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.

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].

2-Iodo-N-(6-methyl-2-pyrid-yl)benzamide.

The asymmetric unit of the title compound, C13H11IN2O, comprises two crystallographically independent molecules. The dihedral angles between the ring planes are 53.56 (9) and 72.14 (19)° in the two molecules. Pairs of intermolecular N—H⋯N hydrogen bonds and I⋯O interactions link neighbouring molecules into two different pairs of dimers, those involving N—H⋯N interactions having R 2 2(8) ring motifs. Short intermolecular I⋯O [3.1458 (15) Å] and I⋯N [3.4834 (16) Å] contacts are present. The crystal structure is further stabilized by intermolecular C—H⋯π interactions [3.565 (2) and 3.629 (2) Å].

3,5-Dichloro-6-methyl­pyridin-2-amine

In the title compound, C6H6Cl2N2, intramolecular N–H⋯Cl and C—H⋯Cl contacts generate five-membered rings, producing S(5) ring motifs. Pairs of intermolecular N—H⋯N hydrogen bonds link neighbouring molecules into dimers with R 2 2(8) ring motifs. In the crystal structure, these dimers are connected by N—H⋯Cl interactions and are packed into columns.

N‐(7‐Dimethoxymethyl‐4‐oxo‐3,4‐dihydropteridin‐2‐yl)‐2,2‐dimethylpropionamide monohydrate

In the title compound, C14H19N5O4·H2O, the 3,4-dihydropteridine ring system deviates sigificantly from planarity, the dihedral angle between the mean planes of the two rings being 3.93 (9)°. Intramolecular N—H...O hydrogen bonding generates an S(6) ring motif. The water molecule forms O—H...O and O—H...N intramolecular hydrogen bonds with the substituted pteridine molecule. In the crystal structure, the substituted pteridine molecules are linked by N—H...N hydrogen bonds into chains running along the c direction. These chains are further connected to the water molecules by N—H...O, O—H...O and O—H...N hydrogen bonds to form two-dimensional networks parallel to the bc plane. The crystal structure is stabilized by intra- and intermolecular N—H...O, N—H...N, O—H...O and O—H...N hydrogen bonds, together with weak C—H...O and C—H...N intra- and intermolecular interactions. C—H...π interactions are also observed.