Synthesis, characterization and catalytic application of silica supported tin oxide nanoparticles for synthesis of 2,4,5-tri and 1,2,4,5-tetrasubstituted imidazoles under solvent-free conditions

AbstractHighly efficient and eco-friendly, one pot synthesis of 1,2,4,5-tetra substituted imidazoles and 2,4,5-trisubstituted imidazoles was reported under solvent free conditions using nanocrystalline silica supported tin oxide (SiO2:SnO2) as a catalyst with excellent yield. The present methodology offers several advantages such as mild reaction conditions, short reaction time, good yield, high purity of product, recyclable catalyst without a noticeable decrease in catalytic activity and can be used for large scale synthesis. The synthesized SiO2:SnO2 nanocrystalline catalyst was characterized by XRD, BET surface area and TEM techniques

Chern-Simons Invariants of Torus Links

We compute the vacuum expectation values of torus knot operators in Chern-Simons theory, and we obtain explicit formulae for all classical gauge groups and for arbitrary representations. We reproduce a known formula for the HOMFLY invariants of torus links and we obtain an analogous formula for Kauffman invariants. We also derive a formula for cable knots. We use our results to test a recently proposed conjecture that relates HOMFLY and Kauffman invariants.Comment: 20 pages, 5 figures; v2: minor changes, version submitted to AHP. The final publication is available at http://www.springerlink.com/content/a2614232873l76h6

Pharmacological targeting of MTHFD2 suppresses acute myeloid leukemia by inducing thymidine depletion and replication stress

The folate metabolism enzyme MTHFD2 (methylenetetrahydrofolate dehydrogenase/cyclohydrolase) is consistently overexpressed in cancer but its roles are not fully characterized, and current candidate inhibitors have limited potency for clinical development. In the present study, we demonstrate a role for MTHFD2 in DNA replication and genomic stability in cancer cells, and perform a drug screen to identify potent and selective nanomolar MTHFD2 inhibitors; protein cocrystal structures demonstrated binding to the active site of MTHFD2 and target engagement. MTHFD2 inhibitors reduced replication fork speed and induced replication stress followed by S-phase arrest and apoptosis of acute myeloid leukemia cells in vitro and in vivo, with a therapeutic window spanning four orders of magnitude compared with nontumorigenic cells. Mechanistically, MTHFD2 inhibitors prevented thymidine production leading to misincorporation of uracil into DNA and replication stress. Overall, these results demonstrate a functional link between MTHFD2-dependent cancer metabolism and replication stress that can be exploited therapeutically with this new class of inhibitors

Sunlight assisted photocatalytic degradation of Indigo Carmine using eco-friendly synthesized CdSnO3

In the present study I have developed an eco-friendly mechanochemical solid state method with green chemistry approach for the synthesis of CdSnO3. The photocatalyst was characterized to carry out physicochemical characterization by various analytical techniques like, Fourier Transform Infrared (FT-IR), Ultraviolet diffused reflectance Spectroscopy (UV-DRS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Tunnelling Electron Microscopy (TEM) and Brunauer–Emmett– Teller (BET) surface area. The synthesized CdSnO3 particles had an average size of 105 nm with band gap 3.17 eV. The surface area by BET isotherm method highlight for the synthesized photocatalyst (SBET) is 54.45 m2/g, with pore volume (Vp) is 0.021 cc/g, and pore diameter (Dp) is 24.85 Aº. Photocatalytic activity of CdSnO3 was demonstrated by degradation of Indigo carmine dye under influence of sunlight in aqueous solutio

Synthesis, crystal structure and characterization of Na_2.02Ag_5.98[GaSiO₄]₆(NO₂)₂and Na_3.12K_4.88[GaSiO₄]₆(NO₂)₂ sodalites

563-567Partially exchanged silver and potassium derivatives of Na8[GaSiO4]6(NO2)2 sodalite, Na2.02Ag5.98[GaSiO4]6(NO2)2 and Na3.12K4.88[GaSiO4]6(NO2)2, have been studied. The nitrite sodalite of the composition, Na8[GaSiO4]6(NO2)2 was prepared at low temperature by hydrothermal technique and the derivatives Na2.02Ag5.98[GaSiO4]6(NO2)2 and Na3.12K4.88[GaSiO4]6(NO2)2, were obtained by cation exchange method at 373 K. These products crystallize with the cubic sodalite structure in the space group P43n and profile refinement of powder X-ray data has been completed. The products obtained were studied by different investigative techniques like IR spectroscopy, X-ray powder diffraction, UV-DRS and SEM. FTIR study shows shift in absorption frequency for the exchange of silver and potassium derivatives. The unit cell parameters (a) are found to be 8.9328, 8.9838 and 9.0409 Å for silver, sodium and potassium sodalites, respectively, while the bond distances and bond angles are modified considerably. UV-DRS study shows shift in bands and change in band gap energy of these sodalite derivatives. SEM shows surface morphology of these sodalites

Synthesis and characterization of gallosilicate halide sodalites using organic solvent

1047-1051The crystallization of gallosilicate sodalite containing halides (Cl, Br and I) in 30% ethanol have been investigated at low temperature (373 K) using one pot synthesis method. X-ray powder diffraction, IR, FAR IR, 29Si and 23Na MAS NMR, SEM and thermogravimetric data are used to characterize these sodalites. The crystal structures show cubic symmetry in a space group P3n. The crystal structures have been refined by Rietveld refinement method. The unit cell parameter, a = 8.9502, 8.9986 and 9.0779 Å and the corresponding Ga-O-Si angle are found to be 134.453, 135.252 and 136.887o for chloro, bromo and iodo sodalite respectively. The MAS NMR data confirm the alternating Ga and Si ordering of sodalite framework. TGA analysis shows stability of guest anions in the sodalite framework

One-Pot Synthesis, X-Ray Diffraction and MAS NMR Spectroscopic Study of Gallosilicate Nitrate Cancrinite Na8[GaSiO4]6(NO3)4(H2O)6

One-pot synthetic gallosilicate nitrate cancrinite (CAN) framework topology have been synthesized under hydrothermal conditions at 100 °C. The synthesized product was characterized by, X-ray powder diffraction, IR, Raman and 29Si, 23Na MAS NMR spectroscopy, SEM and thermogravimetry. The crystal structure refinement of pure nitrate cancrinite has been carried out from X-ray data using Rietveld refinement method. Gallosilicate cancrinite Na8[GaSiO4]6(NO3)4(H2O)6 crystalline hexagonal with space group P63 and a = 12.77981 Å (2), c = 5.20217 Å (1), (Rwp = 0.0696 Rp = 0.0527). The results by MAS NMR spectroscopy confirmed the alternating Si, Ga ordering of the gallosilicate framework for a Si/Ga ratio of 1.0. A distribution of the quadrupolar interaction of the sodium cations caused by the enclatherated water molecules and motional effects can be suggested from the 23Na MAS NMR. Thermogravimetric investigation shows the extent of nitrate entrapment, stability within the cancrinite cage and decomposition properties. SEM clearly shows the hexagonal needle shaped crystals of nitrate cancrinite