Control of polymorphism in coronene by the application of magnetic fields

Coronene, a polyaromatic hydrocarbon, has been crystallized for the first time in a different polymorph using a crystal growth method that utilizes magnetic fields to access a unit cell configuration that was hitherto unknown. Crystals grown in magnetic field of 1 T are larger, have a different appearance to those grown in zero field and retain their structure in ambient conditions. We identify the new form, beta-coronene, as the most stable at low temperatures. As a result of the new supramolecular configuration we report significantly altered electronic, optical and mechanical properties.Comment: 32 pages, 17 figure

Synthesis of porous high-temperature superconductors via a melamine formaldehyde sacrificial template

Nanostructured high-temperature superconductors YBa(2)Cu(3)O(6+δ) and Bi(2)Sr(2)CaCu(2)O(8+δ) were synthesised using a melamine formaldehyde sponge as a sacrificial template, via three solution-based approaches. In the case of YBa(2)Cu(3)O(6+δ), a modified Pechini method produced a material with a superconducting transition at 92 K and a specific surface area of 4.22 m(2) g(−1). Further analysis with Hg porosimetry determined that the sponge exhibited a porosity of 82%. In the case of Bi(2)Sr(2)CaCu(2)O(8+δ), this method produced a material that exhibited superconductivity at 86 K with a specific surface area of 9.62 m(2) g(−1). Hg-porosimetry determined that the BSCCO sponge exhibited a porosity of 78%