Morphology controlled nano-structures of an octa(phenoxy)-substituted phthalocyaninato zinc complex: solvent effect on the self-assembly behaviour

Abstract

The 2,3,9,10,16,17,24,25-octakis(phenoxy)phthalocyaninato zinc, (Zn[Pc(OPh)₈]) was fabricated into nano-/micro-structures via solution-phase self-assembly. The self-assembling properties of Zn[Pc(OPh)₈] in coordinating and non-coordinating solvents (methanol and n-hexane) have been comparatively studied by electronic absorption, fluorescence, Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. The conducting properties were evaluated by current–voltage (I–V) measurements. Due mainly to the presence of different intermolecular Zn–O coordination interactions between the Zn[Pc(OPh)₈] molecules in n-hexane and between the Zn[Pc(OPh)₈] and solvent molecules in methanol, the self-assembly of the Zn[Pc(OPh)₈] results in nano-/micro-structures with distinctly different morphology as follows: nanobelts in n-hexane, and soft nano-sticks, microscale needle mushroom as well as pine leaves in methanol depending on aggregation time. The size and/or morphological evolution of the nanostructures have been clearly revealed during the self-assembly process. The present result appears to represent the first effort toward realization of controlling and tuning the biomorphs of self-assembled nanostructures of phthalocyanine-related complexes through the solvent coordinating effect. Furthermore, both nanobelts and micrometer-sized pine leaves were revealed to show good semiconductor features.