RESUMO
The molecular arrangements of three different alkyl-substituted oligothiophenes both in two-dimensional adsorbed layers at a substrate interface and in bulk three-dimensional crystals were studied. Scanning tunneling microscopy (STM) was used to investigate the ordering of the conjugated oligomers in two-dimensional layers adsorbed on graphite. These data were compared with the X-ray structure determinations of single crystals revealing the arrangement in the three-dimensional bulk material. Quaterthiophenes 1 and 2, bearing dodecyl and hexyl side chains, respectively, exhibit a lamella-type stacking of the conjugated backbone concomitant with an interlocking of the alkyl side chains both on the surface and in the crystal. In contrast, the arrangement of propyl-substituted quaterthiophene 3 is rather "herringbone-like" due to the reduced interactions of the shorter alkyl side chains. In all three cases, evidently, the two-dimensional ordering at the graphite surface is coincident with the molecular packing in one cross-section of the three-dimensional crystal.
RESUMO
The structural spectroscopic, and thermal properties of a complex of sulfacetamide (Hsacm) with Cu(II) have been investigated. The complex [Cu(Hsacm)2(NO3)2] crystallizes in the monoclinic system, space group P2(1)/n. The cell dimensions are a = 7.696(7) A, b = 8.017(7) A, c = 19.230(10), beta = 110.80(1) degree, V = 1109(1) A3, Z = 2, and Dx = 1.84 g/cm3. The structure was refined to R = 0.0776. Cu(Hsacm)2(NO3)2 molecules form a long polymeric chain extended along the b-axis. The copper(II) coordinated geometry is tetragonally distorted octahedral with two amino nitrogens from Hsacm and two oxygens from nitrato anions in the basal plane and two acetamido oxygens from neighbor Hsacm molecules in the apical position. Each sulfacetamide, acting as a bidentate ligand, links two Cu(II) ions as a bridge through the Namino and the Oacetamido atoms. The complex proved to possess higher bacteriostatic activity than the corresponding ligand.
