Logesh Mathivathanan

Uracil Nucleosides with Reactive Group at C5 Position: 5-(1-Halo-2-sulfonylvinyl)uridine Analogues.

The transition-metal-catalyzed or radical-mediated halosulfonylation of 5-ethynyluridine provided (E)-(1-halo-2-tosylvinyl)uridines. These (β-halo)vinyl sulfones undergo efficient stereoselective addition-elimination with amines or thiols to provide Z-β-aminovinyl or E-β-thiovinyl sulfones tethered to the C5 position of the uracil ring.

Nitroaromatic sensing with a new lanthanide coordination polymer [Er2(C10H4O4S2)3(H2O)6]n assembled by 2,2′-bithiophene-5,5′-dicarboxylate

A new three dimensional lanthanide-containing coordination polymer composed of 2,2′-bithiophene-5,5′-dicarboxylic acid ([Er2(C10H4O4S2)3(H2O)6]n) was solvothermally synthesized and characterized using single crystal X-ray diffraction, PXRD, FTIR, TGA, and luminescence measurements. The emission of this compound dispersed in ethanol is linker based and is quenched upon addition of nitroaromatic species due to a charge transfer from the MOF to the nitroaromatic species. This compound is able to sense a variety of nitroaromatic species, but is particularly sensitive to nitrophenols and nitroaniline.

Synthesis of 8-(1,2,3-triazol-1-yl)-7-deazapurine nucleosides by azide–alkyne click reactions and direct CH bond functionalization

Treatment of toyocamycin or sangivamycin with 1,3-dibromo-5,5-dimethylhydantoin in MeOH (r.t./30 min) gave 8-bromotoyocamycin and 8-bromosangivamycin in good yields. Nucleophilic aromatic substitution of 8-bromotoyocamycin with sodium azide provided novel 8-azidotoyocamycin. Strain promoted click reactions of the latter with cyclooctynes resulted in the formation of the 1,2,3-triazole products. Iodine-mediated direct C8-H bond functionalization of tubercidin with benzotriazoles in the presence of tert-butyl hydroperoxide gave the corresponding 8-benzotriazolyltubercidin derivatives. The 8-(1,2,3-triazol-1-yl)-7-deazapurine derivatives showed moderate quantum yields and a large Stokes shifts of ~ 100 nm.

A [Cu3(μ3-O)]–pyrazolate metallacycle with terminal nitrate ligands exhibiting point group symmetry 3

The cuprate anion in the title compound is located about a threefold rotation axis and hence forms an almost planar Cu3(μ3-O)-core, where the μ3-O atom is located 0.12 Å above the Cu3 plane.

Remarkably selective NH4+ binding and fluorescence sensing by tripodal tris(pyrazolyl) receptors derived from 1,3,5-triethylbenzene: structural and theoretical insights on the role of ion pairing

A fluorescent sensor for NH4+ based on 1,3,5-triethylbenzene shows remarkable binding and sensing selectivity for NH4+vs. K+. Fluorescence and NMR titrations reveal surprising differences in the sensing properties and binding constants of tris-(3,5-dimethyl)pyrazole 1vs. tris(3,5-diphenyl)pyrazole 2. The roles of ion pairing and solvation are revealed by X-ray and DFT studies.

Crystal structure of μ6-chlorido-nona­kis­(μ-4-chloro­pyrazolato)bis-μ3-methoxo-hexa­copper(II)

The hexanuclear copper pyrazolato complex has a trigonal prismatic shape and contains an encapsulated chloride ligand.

Crystal structure and conformational analysis of doxorubicin nitrate

The conformations of the two free doxorubicin (DoxH+) cations present in the crystal structure of the title compound and (Dox) bound to proteins and DNA are compared.

3,5-Bis(2,4-dinitro­phen­yl)-4-nitro-1H-pyrazole acetone monosolvate

The title structure, C15H7N7O10·C3H6O, was prepared by pentanitration of 3,5-diphenyl-1H-pyrazole. The proton attached to a pyrazole N atom forms a hydrogen bond with the O atom of the acetone solvent molecule, owing to the NO2 enhanced acidity of the proton. The NO2 group on the phenyl C atom is twisted by 33.9 (2)° from coplanarity with the ring in order to avoid a short intramolecular O⋯O contact with an O atom of an adjacent pyrazole-bonded NO2 group.