Synthesis, Characterization And Organic Aggregation Properties Of Unsymmetrical "3+1" Phthalocyaninato Zinc Complexes

Owing to the unique optical, electrical, and magnetic properties, associated with the intriguing intermolecularπ-πinteractions, phthalocyanines, as novel functional materials, have been expected to be widely applied in materials science, such as in molecular electronics, molecular information storage, and nonlinear optics, etc. Transesterification reactions have been widely used in organic synthesis, this process has also been reported during the preparation of phthalocyanines with ester derivatives. Recently, it is significantly interested in ordered supramolecular aggregates and nanoscale assembly fields. In our thesis, we have synthesized a series of unsymmetrical phthalocyaninato zinc complexes with special molecular structures and particular characteristics via transesterification; We have also obtained highly ordered nanostructures through self-assembly process, and the mechanism of the self-assembly process has also been discussed, indicating the effect of the solvent on tuning the intermolecular interaction and in turn the molecular packing mode in the aggregates of phthalocyanine compounds. Our research work has been focused on the following two respects:1. Synthesis and Characterization of the Unsymmetrical "3+1" Phthalocyaninato Zinc ComplexesTreatment of the 4,5-dichlorophthalonitrile with 4-hydroxybenzoate or dimethyl-5-hydroxyisophthalate in the presence of K2CO3 in DMF gave corresponding ligands. These compounds were then treated with an excess of phthalonitriles in the presence of Zn(OAc)2-2H2O and DBU in different alcohols including pentanol and octanol. Under these conditions, transesterification occurred, giving the corresponding "3+1" phthalocyaninato zinc complexes. In these reactions, DBU served not only as the catalyst for the cyclization of phthalonitriles, but also as the catalyst for the transesterification. During the reaction, the temperature was kept higher than 130℃to remove the methanol generated which can shift the equilibrium to the product side. These long aliphatic chains can increase the solubility of the resulting phthalocyanines and facilitate their isolation. The series of unsymmetrical "3+1" phthalocyaninato zinc complexes were characterized by elemental analysis and various spectroscopic methods (MS, NMR, UV-vis and IR).2. Self-assembly Properties of the Unsymmetrical "3+1" Phthalocyaninato Zinc ComplexHighly orderly nanostructures obtained from the self-assembly of the organic functional molecular will be widely applied in nanoscience and nanotechnology. In recent years, the self-assembly process through the weak intermolecular interaction between the molecules has always been the focus of the scientific researchers. But for scientists, to obtain the ideal morphology via molecular design to adjust the molecular interactions is still a challenge. In this chapter, we self-assembled the unsymmetrical phthalocyaninato zinc complex in different solvent systems and got the organic nanoaggregates, and comparatively studied their characteristics through the ultraviolet (UV), Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. The result indicates that solvent systems play a very important role in dominating the morphology of the aggregates. Intermolecularπ-πinteraction in cooperation with the van der Waals interaction for the unsymmetrical zinc phthalocyanine lead to the formation of ring-shaped nanostructures with the outer diameter of the rings in the range of 1.35-1.83μm and the average width of the bands for the rings varying between 110 and 140 nm at the chloroform/water interface and star-shaped nanostructures with several micrometer length and ca. 300-400 nm width in the chloroform/methanol system, respectively. Electronic absorption spectroscopic results reveal the J-aggregate and H-aggregate nature in the ring-shaped and star-shaped nanostructures, respectively, indicating the effect of the solvent on tuning the intermolecular interaction and in turn the molecular packing mode in the aggregates of phthalocyanine compound. The result indicates that the solvent systems play a very important role in regulating and controlling the nanostructures of the phthalocyaninato compounds, and this will be helpful for us to prepare and regulate functional organic nanostructures at the molecular level.