Crystal and molecular structure of an inclusion compound formed between 2′,6′-dimethoxyflavone and perchloric acid. Comparative study with other acid solvates

Crystal determination of a complex between 2,6-dimethoxyflavone and perchloric acid revealed that the inclusion compound contains a water of crystallization that participates in hydrogen bonds connecting the perchloric anion and the carbonyl oxygen of the flavone. The torsion angle between the-benzopyrene and the phenyl rings O(1)C(2)C(1)C(6) is –45, which gives a less twisted molecule than the parent molecule or other inclusion compounds with carboxylic acids. A comparative study with these structures shows that the hydrogen bond forces coplanarity between the-benzopyrone and phenyl rings.     

A second triclinic modification of 2′,6′‐di­methoxy­flavone

Crystals of a second triclinic modification of the title compound, 2‐(2,6‐di­methoxy­phenyl)‐4H‐1‐benzo­pyran‐4‐one, C₁₇H₁₄O₄, were grown from a hot cyclo­hexane solution. In the mol­ecule, the O—C—C—C torsion angle at the junction between the benzo­pyran and phenyl rings is 67.6 (3)°.     

The 1∶1-adduct of chlorotriphenyltin with 2′,6′-dimethoxyflavone: a potential fungicide

The 11 adduct of chlorotriphenyltin with 2,6-dimethoxyflavone, (C₃₅H₂₉O₄ClSn)Mr=667.78, crystallizes in the triclinic space groupP1 with the following data:a-9.094(2),b=12.369(3),c=14.674(3) Å, =74.78(2), =77.00(2), =73.06(3)°,V=1503.8(4) ų,Z=2, Mo-K, =9, 8 cm^–1,Dc=1.475 g cm^–3, F(000)=676,T=293K. The structure was solved by direct-methods and has been refined to a finalR value (l>3(I)) of 0.0301. The flavone coordinates to the tin atom through the carbonyl oxygen atom. The metal center exhibits a trigonal bipyramidal configuration with the three phenyl groups in equatorial positions.     

Preparation and characterization of MgB2 superconductor

The MgB₂ superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties. The upper critical field, irreversibility line and critical current density have been determined using magnetization data. The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition. The surface analysis using X-ray photoelectron spectroscopy shows that MgB₂ is sensitive to atmospheric degradation.     

Quantum Hall conductivity in a Landau type model with a realistic geometry

In this paper, we revisit some quantum mechanical aspects related to the quantum Hall effect. We consider a Landau type model, paying a special attention to the experimental and geometrical features of quantum Hall experiments. The resulting formalism is then used to compute explicitely the Hall conductivity from a Kubo formula.