RESUMO
Initial stages of two-dimensional crystal growth of the double-decker sandwich complex Lu(Pc*)2 [Pc* = 2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] have been studied by scanning tunneling microscopy at the liquid/solid interface between 1-phenyloctane and highly oriented pyrolytic graphite. High-resolution images strongly suggest alignment of the double-decker molecules into monolayers with the phthalocyanine rings parallel to the surface. Domains were observed with either hexagonal or quadrate packing motifs, and the growing interface of the layer was imaged. Molecular resolution was achieved, and the face of the phthalocyanine rings appeared as somewhat diffuse circular features. The alkyl chains are proposed to be interdigitating to maintain planar side-by-side packing.
RESUMO
Poly(3-hexylthiophene)-single-walled carbon nanotubes (SWNTs) composites were studied using UV-visible absorbance and Raman spectroscopy, scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Monolayers of regioregular poly(3-hexyl thiophene) (rrP3HT) adsorbed on SWNTs have been imaged using scanning tunneling microscopy (STM) to obtain measurements of the chiral angles at which the thiophene polymer chains wrap around individual carbon nanotubes (41-48 degrees with respect to nanotube axis) and polymer interchain spacings (1.68 angstroms). The rrP3HT interchain distance is greater for rrP3HT monolayers adsorbed onto the curved surfaces of SWNTs than on the flat surfaces of highly ordered pyrolytic graphite samples (1.4 angstroms). UV-vis spectroscopic data provided strong evidence for increased interchain interactions in composites of rrP3HT and SWNTs compared to the pure polymer. The STM local-probe studies of the native polymer and the composites further confirmed that the rrP3HT interacts with carbon nanotubes to produce a highly ordered material at the molecular level.