Preparation And Properties Of Tetra-substituted Zinc Phthalocyanine Compounds

Since the accidental synthesis of phthalocyanines?Pcs?by Imperial Chemical Industries in 1928,Pcs have found high-tech applications in electrophotography and ink jet printing and as photoconducting agents in photocopying devices.In addition,the importance and potential of Pcs is rapidly growing in many other fields such as catalysts,gas sensor,electrochromic devices,liquid crystals,semiconductor and dye sensitized solar cell,thanks to their excellent stability,improved spectroscopic characteristics,diverse coordination properties,and architectural flexibility.A notorious disadvantage of Pcs is that their unsubstituted derivatives have extreme insolubility in common organic solvents.In this study,we focused on the synthesis and characterization of five soluble Pcs.The aim of this study is to investigate the aggregation and the spectroscopic properties of phthalocyanine derivatives in different concentration ranges.In addition,the redox activities of phthalocyanine derivatives in certain organic solvents were also discussed.First precursors were synthesized from 4-nitro-phthalonitrile,hydroquinone,1-bromooctane,1-bromopentane,phenol,2-hydroxy naphthalene and 2-methyl-8-hydroxyquinoline under the catalysis of anhydrous potassium carbonate via nucleophilic substitution reactions.Then the precursors were reacted with zinc acetate with1,8-diazabicyclo[5.4.0]-undec-7-ene?DBU?as the catalyst to give five zinc Pcs.,which are2?3?,9?10?,16?17?,23?24?-tetra?p-pentyloxyphenoxy?phthalocyanine zinc,2?3?,9?10?,16?17?,23?24?-tetra?p-octyloxyphenoxy?phthalocyanine zinc,2?3?,9?10?,16?17?,23?24?-tetra?p-phenoxy?phthalocyanine zinc,2?3?,9?10?,16?17?,23?24?-tetra?p-napthoxy?phthalocyanine zinc,and 2?3?,9?10?,16?17?,23?24?-tetra?2-methyl-8-oxy-quinoline?phthalocyanine zinc,respectively.The structures of both the precursors and targated products have been characterized by IR,UV-visible spectroscopy,elemental analysis and NMR.The energy level position of the ground state oxidation potential and the excited-state oxidation potential for the six complexes were determined by UV-visible spectroscopy,cyclic voltammetry curves and differential pulse voltammetry.The UV-visible spectrum exhibited the maximum absorption peak of Q band at around680-685 nm with varying degrees of red shift for the aryloxy Pcs.The excited electron can be easily injected into the TiO₂ conduction and the oxidized state of dye can get reduced by taking electron from redox electrolyte,satisfying the energy gap rule,and indicating that it can be employed as sensitizer for DSSC application.