An experimental and computational study on isomerically pure, soluble azaphthalocyanines and their complexes and boron azasubphthalocyanines of a varying number of aza units.

Herein, we present a series of isomerically pure, peripherally alkyl substituted, soluble and low aggregating azaphthalocyanines as well as their new, smaller hybrid homologues, azasubphthalocyanines. The focus lies on the effect of the systematically increasing number of aza building blocks [-N[double bond, length as m-dash]] replacing the non-peripheral [-CH[double bond, length as m-dash]] units and their influence on the physical and photophysical properties of these chromophores. The absolute and relative HOMO-LUMO energies of azaphthalocyanines were analyzed using UV-Vis and CV and compared to the density functional theory calculations (B3LYP, TD-DFT). The lowering of the HOMO level is revealed as the determining factor for the trend in the adsorption energies by electronic structure analysis. Crystals of substituted subphthalocyanines, N2-Pc*H2 and N4-[Pc*Zn·H2O], were obtained out of DCM. For the synthesis of the valuable tetramethyltetralin phthalocyanine building block a new highly efficient synthesis involving a nearly quantitative CoII catalyzed aerobic autoxidation step is introduced replacing inefficient KMnO4/pyridine as the oxidant.

Template-controlled on-surface synthesis of a lanthanide supernaphthalocyanine and its open-chain polycyanine counterpart.

Phthalocyanines possess unique optical and electronic properties and thus are widely used in (opto)electronic devices, coatings, photodynamic therapy, etc. Extension of their π-electron systems could produce molecular materials with red-shifted absorption for a broader range of applications. However, access to expanded phthalocyanine analogues with more than four isoindoline units is challenging due to the limited synthetic possibilities. Here, we report the controlled on-surface synthesis of a gadolinium-supernaphthalocyanine macrocycle and its open-chain counterpart poly(benzodiiminoisoindoline) on a silver surface from a naphthalene dicarbonitrile precursor. Their formation is controlled by the on-surface high-dilution principle and steered by different metal templates, i.e., gadolinium atoms and the bare silver surface, which also act as oligomerization catalysts. By using scanning tunneling microscopy, photoemission spectroscopy, and density functional theory calculations, the chemical structures along with the mechanical and electronic properties of these phthalocyanine analogues with extended π-conjugation are investigated in detail.