Phthalocyaninato complexes with peripheral alkylthio chains: Disk-like adsorbate species for the vertical anchoring of ligands onto gold surfaces

The MnIII phthalocyaninato complexes [Mn(1a)Cl] and [Mn(1b)Cl], which each contain eight peripheral long-chain alkylthio substituents (S-n-C8H17 and S-n-C12H25, respectively), form high-quality self-assembled monolayers on gold. The chemisorption leads to Cl loss and results in MnII-like behaviour through electronic manganese–gold interactions. [Display omitted] ► MnIII phthalocyaninato complexes with an axial chlorido ligand and eight peripheral long-chain alkylthio substituents form high-quality SAMs on gold. ► The thioether units chemisorb intact on the substrate. ► The disk-like macrocycles are in a parallel orientation with respect to the substrate surface. ► The chemisorption causes loss of the axial chlorido ligand and reduction to MnII. ► Analogous ZnII phthalocyaninato complexes containing an axial pyridine ligand were structurally characterised. Thin metalorganic films were prepared on gold by self-assembly of thioether-functionalised phthalocyaninato complexes from solution. The phthalocyaninato ligands used contain eight peripheral, β-positioned, alkylthio substituents SR (1a: R=n-C8H17, 1b: R=n-C12H25), which serve as headgroups for surface binding and promote lateral assembly, while the disk-like phthalocyaninato core offers the scope for the attachment of axial ligands to the adsorbed molecules. This process was mimicked by coordination of pyridine (Py) to [Zn(1a)] and [Zn(1b)], respectively. The crystal structures of the products [Zn(1a)(Py)] and [Zn(1b)(Py)] were determined. The crystal structures of 4,5-bis(octylthio)phthalodinitrile and 4,5-bis(dodecylthio)phthalodinitrile were also determined. The films fabricated from [Mn(1a)Cl] and [Mn(1b)Cl] on gold were characterised by XPS, ToF-SIMS and NEXAFS spectroscopy, which revealed the presence of well-defined and homogeneous self-assembled monolayers (SAMs), whose constituents are bound to the substrate by thioether–gold linkages. The orientation of the macrocycles is predominantly parallel to the surface. Strong electronic interaction of the manganese(III) centre with the substrate leads to Cl loss upon adsorption and its reduction to MnII.