University of Hyderabad

About: University of Hyderabad is a education organization based out in Hyderabad, India. It is known for research contribution in the topics: Catalysis & Crystal structure. The organization has 6446 authors who have published 13005 publications receiving 237641 citations. The organization is also known as: Hyderabad Central University & HCU.

Tuning the spin-transition properties of pyrene-decorated 2,6-bispyrazolylpyridine based Fe(II) complexes.

Abstract: Two 2,6-bispyrazolylpyridine ligands (bpp) were functionalized with pyrene moieties through linkers of different lengths. In the ligand 2,6-di(1H-pyrazol-1-yl)-4-(pyren-1-yl)pyridine (L1) the pyrene group is directly connected to the bpp moiety via a C–C single bond, while in the ligand 4-(2,6-di(1H-pyrazol-1-yl)pyridin-4-yl)benzyl-4-(pyren-1-yl)butanoate (L2) it is separated by a benzyl ester group involving a flexible butanoic chain. Subsequent complexation of Fe(II) salts revealed dramatic the influence of the nature of the pyrene substitution on the spin-transition behaviour of the resulting complexes. Thus, compound [Fe(L1)2](ClO4)2 (1) is blocked in its high spin state due to constraints caused by a strong intermolecular π–π stacking in its structure. On the other hand, the flexible chain of ligand L2 in compounds [Fe(L2)2](ClO4)2 (2) and [Fe(L2)2](BF4)2·CH3CN·H2O (3) prevents structural constraints allowing for reversible spin transitions. Temperature-dependent studies of the photophysical properties of compound 3 do not reveal any obvious correlation between the fluorescence of the pyrene group and the spin state of the spin transition core.

Search for charged Higgs bosons in the H-+/- -> tau(+/-)nu(tau) decay channel in proton-proton collisions at s=13 TeV

Abstract: A search is presented for charged Higgs bosons in the H$^{±}$ → τ$^{±}$ν$_{τ}$ decay mode in the hadronic final state and in final states with an electron or a muon. The search is based on proton-proton collision data recorded by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{−1}$. The results agree with the background expectation from the standard model. Upper limits at 95% confidence level are set on the production cross section times branching fraction to τ$^{±}$ν$_{τ}$ for an H$^{±}$ in the mass range of 80GeV to 3TeV, including the region near the top quark mass. The observed limit ranges from 6 pb at 80 GeV to 5 fb at 3 TeV. The limits are interpreted in the context of the minimal supersymmetric standard model m$_{h}^{hod −}$ scenario.

Crystal Structures of N-Aryl-N′-4-Nitrophenyl Ureas: Molecular Conformation and Weak Interactions Direct the Strong Hydrogen Bond Synthon

Abstract: Hydrogen bond competition was studied in 21 X-ray crystal structures of N-X-phenyl-N′-p-nitrophenyl urea compounds (X = H, F, Cl, Br, I, CN, C≡CH, CONH2, COCH3, OH, Me). These structures are classified into two families depending on the hydrogen bond pattern: urea tape structures contain the well-known α-network assembled via N−H···O hydrogen bonds; however, in nonurea tape structures the N–H donors hydrogen bond with NO2 groups or solvent O acceptor atoms. Surprisingly, the urea C═O hardly accepts strong H bonds in nonurea type structures sustained by urea···nitro and urea···solvent synthons. The carbonyl group accepts intra- and intermolecular C−H···O interactions. The molecular conformation and H bonding motifs are different in the two categories of structures: the phenyl rings are twisted out of the urea plane in the tape motif, but they are coplanar in the nonurea category. Even though hydrogen bond synthon energy and urea carbonyl acceptor strength favor the N−H···O tape structure, the dominant patt...

Phase Stability and Thermoelectric Properties of the Mineral FeS2: An Ab Initio Study

Abstract: First-principles calculations were carried out to study the phase stability and thermoelectric properties of the naturally occurring marcasite phase of FeS2 at ambient conditions as well as under pressure. Two distinct density functional approaches were used to investigate these properties. The plane wave pseudopotential approach was used to study the phase stability and structural, elastic, and vibrational properties. The full potential linear augment plane wave method has been used to study the electronic structure and thermoelectric properties. From the total energy calculations, it is clearly seen that marcasite FeS2 is stable at ambient conditions, and it undergoes a first-order phase transition to pyrite FeS2 at around 3.7 GPa with a volume collapse of about 3%. The calculated ground-state properties, such as lattice parameters, bond lengths, and bulk modulus of marcasite FeS2, agree quite well with experimental values. In addition, phonon dispersion curves unambiguously indicated that the marcasite...