Diethynyl-Zn-porphyrin-based assemblies: optical and morphological studies of nanostructured thin films

In this paper, we focus our attention on the morphological and optical characterisation of self-assembled Zn-porphyrin-based/fullerene systems. Diethynyl-Zn-porphyrin (ZnDEP) and bimetallic σ-bonded arrays of diethynyl-Zn-porphyrin with Pd(II) and Pt(II) square planar complexes, namely, ZnDEP, Pd–ZnDEP and Pt–ZnDEP, have been synthesised, and these compounds were studied in the self-assembly behaviour with fullerene, giving rise to the molecular composites ZnDEP/C60, Pd–ZnDEP/C60 and Pt–ZnDEP/C60. Thick films of the materials were deposited by slow evaporation on glass substrates, in order to be morphologically characterised by scanning electron microscopy (SEM) technique. The surface analysis showed a peculiar nanometric structure of the composites. The optical (UV–Vis absorption and emission) characterisation of toluene solutions and a preliminary study on the molecular oxygen luminescence quenching of diethynyl-Zn-porphyrin, diethynyl-Zn-porphyrin/fullerene and platinum or palladium-containing homologues have been performed and will be here discussed. A luminescence response towards molecular oxygen was observed in the case of ZnDEP and ZnDEP/C60 samples with a lowering of the intensity of the emission, suggesting promising applications in optical sensors.