Two-Dimensional Self-Assembly and Phase Behavior of an Alkoxylated Sandwich-Type Bisphthalocyanine and Its Phthalocyanine Analogues at the Liquid−Solid Interface

Abstract

Lanthanide bisphthalocyanine complexes are interesting objects for the construction of two-dimensional (2D) ordered arrays with prospective applications in molecular electronics due to their unique semiconductor and electrochromic properties as well as their double-decker architecture. The 2D self-assembly of dodecyloxy-substituted (bisphthalocyaninato)erbium(III) has been studied at the solid (highly oriented pyrolytic graphite)-liquid interface by scanning tunneling microscopy. The results show that the bisphthalocyanine molecules form an ordered quadratic 2D lattice (a = b = 3.0 +/- 0.1 nm, gamma = 90 +/- 3 degrees), which is nearly identical to that formed by its (phthalocyaninato)cobalt(II) analogue bearing alkoxy chains of the same length. This clearly shows that sandwich molecules adsorb to the graphite surface by one of the phthalocyanine disks and its eight alkoxy groups. Despite the very similar mode of interaction with the surface, mixtures of alkoxylated (bisphthalocyaninato)erbium(III) with its (phthalocyaninato)cobalt(II) analogue show partial phase separation on the nanoscale: areas are enriched in one of the compounds. A much clearer phase separation between (bisphthalocyaninato)erbium(III) and (phthalocyaninato)cobalt(II) molecules was achieved by mixing molecules containing alkoxy groups of different length. The results provide insight for the development of well-ordered nanostructures of bisphthalocyanines in the presence of phthalocyanines, which could be of importance for future nanometer-scale functional materials.

Templated bilayer self-assembly of fully conjugated π-expanded macrocyclic oligothiophenes complexed with fullerenes

“…We attribute these islands to a second monolayer of the complex 3 grown epitaxial to the first monolayer, creating a templated bilayer 3 | 3 . Similar bilayers are known to occur by π–π stacking of polycyclic aromatic hydrocarbons42, metallo-ligand interactions of phthalocyanines43 and guest-induced of two layers of TPTC16.…”

Advances in supramolecularly assembled nanostructures of fullerenes and porphyrins at surfaces

“…In recent years, adlayers of several sandwich compounds such as the bisphthalocyanine double-decker complexes of Y, Ce, Pr La, and Er, have been investigated at the liquidsolid interface (mainly on HOPG in 1-phenyloctance) [101][102][103][104][105][106][107]. Possible future applications for these rare earth complexes include their use as organic fieldeffect transistors, liquid crystals, chemical sensors [108] and especially, molecular memory of surfaces, as has been proposed by Lindsey and coworkers [109].…”

Monolayer Assemblies of a Sandwich-Type Double-Decker Porphyrin Complex of Cerium with an Additional Pendant Porphyrin Unit

“…A number of STM studies have been reported on the assemblies of double-decker complexes on different surfaces, addressing different aspects of these assemblies. [15][16][17][18][19][20][21][22] We demonstrated that the orientation and its dynamics of the porphyrin unit within double-decker complexes can be revealed by using porphyrin units with lessthan-four-fold symmetry. Double-decker tetrapyrrole complexes have, in general, four potential minima in their conformation along the rotation of the tetrapyrrole ligands with respect to each other due to the antiprismatic coordination geometry of the metal-ligand bonds as shown in Figure 1.…”