4,5‐Pyrenocyanine—Just Another Phthalocyanine? A STM and 2D WAXS Study

Abstract

Pyrene-fused tetraazaporphyrins were synthesized from pyrene-4,5-dicarbonitrile precursors using a recently reported procedure as the key step for the asymmetric substitution of pyrene. Metal-free, zinc- and lead-centered pyrenocyanines were obtained and their optical properties as well as their molecular assembly in the solution and bulk phases and at the liquid/solid interface were studied. The characteristic Q-band appears broadened, most likely owing to distortion of the molecule introduced by the steric demand of the angularly extended aromatic residue. The angular annulation does not bathochromically shift the Q-band as far as would have been expected for the linear case. Peripheral substitution with linear and branched alkoxy chains affords solubility of the compounds in organic solvents. The influence of the distinct steric demand of the substituents on aggregation was investigated for metal-centered pyrenocyanines by using temperature-dependent (1)H NMR and UV/Vis spectroscopy. The self-assembly at the liquid/solid interface was studied using scanning tunneling microscopy. The alkoxy substituents facilitate the anchoring of these slightly non-planar molecules on the surface of graphite. Pyrenocyanine molecules form well-ordered 2D arrays in which the molecules are arranged in rows. The angular annulation of the pyrenocyanine residue leads to characteristic adsorption behavior at the liquid/solid interface, in which the molecules adsorb in two different adsorption geometries. The alkoxy side-chains give rise to a discotic columnar superstructure and induce distinct thermotropic behavior. Dependent on the steric demand of the branched chains and the central metal atom, the molecules are rotated with respect to each other to form helical organization.

Torands Revisited: Metal Sequestration and Self‐Assembly of Cyclo‐2,9‐tris‐1,10‐phenanthroline Hexaaza Macrocycles

“…On the other hand, Na + , which is a relatively small ion, does not possess d orbitals. A comparison of the STM results with those of 2D‐WAXS discussed above clearly reveals that self‐assembly in the bulk differs from that at the solution–solid interface; the reasons for this have been discussed in detail by us elsewhere 72…”

“…Ac omparison of the STM results with those of 2D-WAXS discussed above clearly reveals that self-assembly in the bulk differs from that at the solutionsolid interface;t he reasons for this have been discussed in detail by us elsewhere. [72] Conclusion New toroidal macrocycles with high structural rigidity were synthesized through the Yamamoto cyclotrimerization of functionalized 1,10-phenathrolines. The unusualh exaaza cavity of these cyclic ligands accommodated an umber of alkaline-, transition-, and heavy-metalc ations and was not deprotonated upon guest inclusion.…”

Manifestations of Non‐Planar Adsorption Geometries of Lead Pyrenocyanine at the Liquid‐Solid Interface

“…Furthermore, they could obtain additional evidence for this hypothesis by imaging monolayers formed by mixing 2HTPP and CoTPP. [18] The contrast variation in case of H 2 -Pyc plausibly arises from different conformations of the pyrene subunits which allow the molecules to attain different equilibrium positions with respect to the HOPG surface. Thus, the contrast variation in the present case could also be explained by considering the presence of free-base impurity in the Pb-Pyc monolayers.…”

“…[18] 1-Phenyloctane was purchased from Sigma-Aldrich (98 %) and was used without further purification. [18] 1-Phenyloctane was purchased from Sigma-Aldrich (98 %) and was used without further purification.…”

Topological Control of Columnar Stacking Made of Liquid‐Crystalline Thiophene‐Fused Metallonaphthalocyanines

“…The optical and electronic properties of MPcs strongly depend on the size of the π‐system . The expansion of the phthalocyanine π‐system has been achieved by condensation of fused polyaromatic precursors . The size and geometry of the annulated aromatic residues on the tetraazaporphyrin core affects the position of the Q band, as well as the HOMO and LUMO energy levels.…”