No abstract

Thin films of pentacene were deposited by thermal evaporation and by pulsed laser deposition (PLD). Surface characterization using atomic force microscopy shows that PLD leads to a reduction in surface roughness, which can be reduced further using heated substrates. Observation of enhanced field-effect carrier mobilities in the PLD films, together with increased electrical conductivity and reduced activation energy for electrical conduction, is consistent with increased molecular ordering in the pentacene films and suggests a direct correlation between molecular ordering in the bulk and surface roughness.

No abstract

The macrocyclic polyether 18-crown-6 (C, 2H2406) readily forms crystalline 1 : 1 complexes with the adducts BF3NH3 and BH3NH3. Crystals of the solvates BF3N.H3C,2H2406CH2C12 and BH3NH3C12H2,06*MeOH were suitable for X-ray crystallographic investigation. In both cases, the crystal structures reveal that 18-crown-6 adopts an all-gauche conformation with pseudo D3d symmetry in which the intermolecular N-H * -0 hydrogen-bonding interactions between the macrocyclic polyether and the adducts are associated directly with the triangle of oxygen atoms on the complexing face of the crown.