Dipak K. Hazra

A cyanide selective off–on fluorescent chemosensor with in vivo imaging in 100% water: solid probe preferred over in situ generation

A nontoxic fluorescent chemosensor [Cu(BP)HMB]2(ClO4)2 (1) synthesized in solid phase, exhibits unprecedented selectivity and sensitivity over the allied in situ complexes to perform fluorescence in “turn-off–on” mode for sensing cyanide in 100% aqueous medium under physiological conditions and for in vivo imaging using the nematode C. elegans. Below μM detection limit, instantaneous and excellent ratiometric responses are also beneficial to detect trace amounts of anthropogenic or biogenic cyanide.

Heterometallic Metal–Organic Frameworks That Catalyze Two Different Reactions Sequentially

A series of copper- and alkaline-earth-metal-based multidimensional metal-organic frameworks, {[CuMg(pdc)2(H2O)4]·2H2O}n (1), [CuCa(pdc)2]n (2), [CuSr(pdc)2(H2O)3]n (3), and {[CuBa(pdc)2(H2O)5]·H2O}n (4), where H2Pdc = pyridine-2,5-dicarboxylic acid, were hydrothermally synthesized and characterized. Two different metals act as the active center to catalyze two kinds of reactions, viz., olefin to its epoxide followed by epoxide ring opening to afford the corresponding vicinal diol in a sequential manner.

Topological features and electronic structure of 4-chloro-1H-pyrrolo[2,3-b]pyridine: experimental charge density analysis and DFT studies

The experimental charge density distribution in 4-chloro-1H-pyrrolo[2,3-b]pyridine has been carried out using high resolution X-ray diffraction data collected at 100(2) K. Multipole refinement based on the Hansen–Coppens formalism coupled with an estimation of anisotropic displacement parameters (ADPs) of hydrogen atoms converged to R(F) = 0.0353 for 5700 reflections with I > 3σ(I) and sin θ/λ ≤ 1.08 A−1. The topology of the bonding scheme within the molecule as well as of the intermolecular N–H⋯N and C–H⋯Cl hydrogen bonds has been investigated. The covalent nature of N–C and C–C bonds in the pyrrolopyridine skeleton of the molecule has been established by (3, −1) bond critical points associated with relatively large electron densities [2.07(2)–2.74(3) e A−3] and highly negative Laplacian values [−11.37(4) to −19.20(10) e A−5]. The topological parameters corresponding to H⋯N and H⋯Cl critical points indicate a moderately strong intermolecular N–H⋯N hydrogen bond and a weak C–H⋯Cl closed-shell interaction. The electronic structure of the title compound has been calculated by density functional theory (DFT) at the BLYP level. A large HOMO–LUMO energy gap (3.59 eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) implies a high kinetic stability of the title compound.

Synthesis, spectroscopic characterization and X-ray structure analyses of two uranyl complexes

Abstract The synthesis, spectroscopic characterization and crystal structures of two uranyl complexes, [UO2(SALEN)(DMF)] (1) and [UO2(BPHA)2(DMF)] (2) {SALEN = N,N′-ethylenebis(salicylimine), DMF = N,N-dimethylformamide, BPHA = N-phenyl benzohydroxamate} are described. The coordination geometry around the metal center in the mononuclear complexes can be best described as distorted pentagonal bipyramidal with an almost linear uranyl moiety. In addition to the van der Waal´s interactions, the crystal packing in the complexes is stabilized by weak intermolecular C–H…O hydrogen bonds involving the uranyl oxygen atoms, so generating two-dimensional arrays in both crystal structures.

4-(3,5-Dimethyl-1H-pyrazol-4-ylmethyl)-3,5-dimethyl-1H-pyrazol-2-ium dihydrogen phosphate: a combined X-ray and DFT study.

The molecular structure of the title salt, C(11)H(17)N(4)(+).H(2)PO(4)(-), has been determined from single-crystal X-ray analysis and compared with the structure calculated by density functional theory (DFT) at the BLYP level. The crystal packing in the title compound is stabilized primarily by intermolecular N-H...O, O-H...N and O-H...O hydrogen bonds and pi-pi stacking interactions, and thus a three-dimensional supramolecular honeycomb network consisting of R(4)(2)(10), R(4)(4)(14) and R(4)(4)(24) ring motifs is established. The HOMO-LUMO energy gap (1.338 eV; HOMO is the highest occupied molecular orbital and LUMO is the lowest unoccupied molecular orbital) indicates a high chemical reactivity for the title compound.

CCDC 1051124: Experimental Crystal Structure Determination

Related Article: Uday Das, Basab Chattopadhyay, Dipak K. Hazra, Vommina V. Sureshbabu, Alok K. Mukherjee|2016|J.Mol.Struct.|1122|290|doi:10.1016/j.molstruc.2016.06.013

C–H···O and C–H··· X ( X = Cl/Br) hydrogen bond tuned supramolecular assembly: a combined X-ray powder diffraction and Hirshfeld surface analysis

Crystal structures of N -(2-chlorophenyl) acetamide ( 1 ) and phenyl (2-bromomethyl) benzoate ( 2 ) have been determined from laboratory X-ray powder diffraction data. In addition to intermolecular N–H···O and C–H···O hydrogen bonds, the crystal packing in ( 1 ) and ( 2 ) exhibits weak C–H···Cl/Br interactions, which facilitate formation of three-dimensional architectures. Hirshfeld surface analysis of compounds ( 1 ), ( 2 ), and a few related chloro- and bromo-phenyl derivatives retrieved from the CSD indicates that 83–97% of Hirshfeld surface areas in this class of compounds are due to H···H, H···π, H···O, and H···Cl/Br contacts.

2,4-Dimethyl-1,3-thiazole-5-carboxylic acid: an X-ray structural study at 100 K and Hirshfeld surface analysis.

The crystal structure of the title thiazolecarboxylic acid derivative, C(6)H(7)NO(2)S, (I), has been determined from single-crystal X-ray analysis at 100 K. In the crystal packing, an interplay of O-H···N and C-H···O hydrogen bonds connects the molecules to form C(6)R(2)(2)(8) polymeric chains, which are further linked via weak C-H···O hydrogen bonds into a two-dimensional supramolecular framework. The relative contributions of different interactions to the Hirshfeld surface in (I) and a few related thiazolecarboxylic acid derivatives indicate that the H···H, N···H and O···H contacts can account for about 50-70% of the total Hirshfeld surface area in this class of compound.