Synthesis and characterization of new octasubstituted phthalocyanines: Supramolecular materials for thin film electronic, optical and chemical sensor applications

Abstract

The synthesis, structure, and properties of a number of new octasubstituted phthalocyanines, were investigated in this work. Substituent functionality and design has a profound influence on the film forming, and hence, chemical/physical properties of these model molecular electronic materials. Highly ordered thin films, of the benzyl terminated Pc, (2,3,9,10,16,17,23,24-octa(2-benzyloxyethoxy) phthalocyaninato) copper, CuPc(OC₂OBz)₈ and its di-hydrogen analogue were prepared and characterized. These materials form ordered Langmuir films composed of close packed columnar assemblies. Full compression of these materials produces thin films of stable bilayers that show remarkable mechanical stability, and can be transferred with high efficiency to substrates using a horizontal transfer protocol. The physical, spectroscopic, spectroelectrochemical, electrochemical, and electronic properties of these materials were characterized. These properties are strongly dependent on film morphology and structure. The conductivity of these materials relative to the Pc column axis, is highly anisotropic, and with electrochemical doping, the conductivity along the column axis is ca. 10⁻⁶ S/cm. 2,3,9,10,16,17,23,24-Octa(2-benzyloxytriethoxy) phthalocyaninato) copper, and di-hydrogen materials were prepared and characterized. These Pc derivatives did not exhibit the extraordinary properties of their shorter chained analogues. Film preparation efforts with these materials produced poorly ordered isotropic films. Chain length and benzyl termination are combined, in CuPc(OC₂OBz)₈, to produce a unique self assembling material with properties comparable to that reported previously for rigid-rod polymeric Pc materials.