Alkane-Assisted Adsorption and Assembly of Phthalocyanines and Porphyrins

Abstract

In this paper it is demonstrated that the stabilizing effect of linear alkanes can be utilized to achieve very high stability in the adsorption and assembly of planar organic molecules on inert surfaces under ambient conditions, by direct deposition from solutions. Using peripherally alkylated phthalocyanines and porphyrins as the examples, optimal resolutions can be achieved with complex molecular systems. Submolecular features of the molecular cores and the interdigitated alkyl parts are clearly visible. Distinctly different packing symmetries were also observed and could be attributed to the intermolecular and adsorbate−substrate interactions. Appreciable contrast variations were also recorded with changing bias voltages. This approach could be adapted to the studies of other molecules to observe submolecular features and could be helpful in obtaining two-dimensional assemblies of monodispersed molecules, especially planar molecules.

Identification of molecular flipping of an asymmetric tris(phthalocyaninato) lutetium triple-decker complex by scanning tunneling microscopy/spectroscopy

“…1(a)). The intermolecular distance estimated from the STM image is about 2.6 nm, in good agreement with the earlier value for a monophthalocyanine CuPcOC8 assembly [37,38], indicating that Lu 2 Pc 3 has adopted a face-on adsorption configuration with the PcOC8 moiety facing towards the graphite surface and the octyloxy groups fully interdigitated with those of the neighboring molecules. In contrast, a disordered assembly was observed at the interface when a positive bias was applied, as shown in Fig.…”

Molecular chirality at surfaces

“…Long alkyl chains at the periphery strongly favor interdigitation and therefore assembly induced chirality (Fig. 14b) [85]. This principle applies to 2D self-assembly of the bowl-shaped C 3 v-symmetric subphthalocyanine (subPC) on Au(111) as well (Fig.…”

Principles of molecular assemblies leading to molecular nanostructures

“…STM has been the method of choice for visualization as well as manipulation of these molecular layers in detail [9][10][11][12][13][14]. It allows imaging of these thin molecular layers adsorbed on atomically flat conductive substrates such as highly oriented pyrolytic graphite (HOPG) and Au(111) with submolecular resolution.…”