Tuning the Framework Formation of Silver(I) Coordination Architectures with Heterocyclic Thioethers

The reactions of a series of nitrogen-containing heterocyclic thioether ligands, 2,2Ј-[methylenebis (thio) , with silver() nitrate or silver() perchlorate salt led to the formation of five new metal-organic supramolecular architectures from dinuclear to threedimensional structures. All the structures were determined by single-crystal X-ray diffraction analysis. In the crystal structures of the five complexes, a variety of coordination modes of Ag I have been observed, probably due to the variation of the chain length of the linker unit or the terminal groups as well as the counter anions, which indicates that the nature of the ligands is a determining factor in controlling the structural topologies of such metal-organic supramolecular architectures. Geometrical effects seem to be more important than electronic effects in these systems, leading the Ag I centre to prefer to coordinate to N donors first rather than S donors despite Ag I being a 'soft' metal

A novel high-spin heterometallic Ni12K4 cluster incorporating large Ni–azide circles and an in situ cyanomethylated di-2-pyridyl ketone

Reaction of di-2-pyridyl ketone (dpk) with nickel acetate and azide in the presence of potassium tert-butylate as a catalytic base generates the title compound, which contains the largest [Ni(m1,1-N3)]6 circles in the discrete ferromagnetically-coupled MII–azide cluster family, and shows an unprecedented in situ cyanomethylation of ketone.Clemente Juan, Juan Modesto, [email protected]

An Updated Search of Steady TeV γ−\gamma-Ray Point Sources in Northern Hemisphere Using the Tibet Air Shower Array

Using the data taken from Tibet II High Density (HD) Array (1997 February-1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV $\gamma-$ray point sources has now been updated by a factor of 2.8 improved statistics. From $0.0^{\circ}$ to $60.0^{\circ}$ in declination (Dec) range, no new TeV $\gamma-$ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV $\gamma-$ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits.Comment: This paper has been accepted by hepn

Isomorphous tetrazolate Mn(II) and Co(II) compounds built on Delta-chain showing different magnetic behaviors

As a continuation of the study on using the tetrazolate ligands to construct coordination polymers, two isomorphous 3D coordination polymers built on Delta-chain topological rod-shaped SBUs have been synthesized with formulae [M(2)(mu(3)-OH)L(1)L(2)](n) (5-amino-1H-tetrazole (HL(1)), 2,3-pyrazinedicarboxylic acid (H(2)L(2)) and different 3d spin carriers (M = Mn(II), 1 and Co(II), 2)). The SBU consists of corner-sharing [M(3)(mu(3)-OH)] isosceles triangle motifs with mixed multiple (mu(4)-tetrazolyl, mu(3)-OH, syn-syn carboxylate) bridges. The SBUs were further linked by syn-anti carboxylates to form the sra net. Spin-competing was observed in the Mn(II) compound, whereas the Co(II) compound exhibits spin-canting.973 Program of China[2007CB815305]; NNSF of China[51073079, 21031002]; Natural Science Fund of Tianjin, China[10JCZDJC22100]; State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen Universit

Overview to the Hard X-ray Modulation Telescope (Insight-HXMT) Satellite

As China's first X-ray astronomical satellite, the Hard X-ray Modulation Telescope (HXMT), which was dubbed as Insight-HXMT after the launch on June 15, 2017, is a wide-band (1-250 keV) slat-collimator-based X-ray astronomy satellite with the capability of all-sky monitoring in 0.2-3 MeV. It was designed to perform pointing, scanning and gamma-ray burst (GRB) observations and, based on the Direct Demodulation Method (DDM), the image of the scanned sky region can be reconstructed. Here we give an overview of the mission and its progresses, including payload, core sciences, ground calibration/facility, ground segment, data archive, software, in-orbit performance, calibration, background model, observations and some preliminary results.Comment: 29 pages, 40 figures, 6 tables, to appear in Sci. China-Phys. Mech. Astron. arXiv admin note: text overlap with arXiv:1910.0443