Rare-earth bisphthalocyaninates

The metallophthalocyanines which have found application as elecfiochromes are mainly the rare earth derivatives, especially lutetium, and second row fiansition metals such as zirconium and molybdenum. Synthesis of these molecules follows the fiaditional routes, e.g. condensation of 1,2-dicyanobenzene with a metal acetate in a high boiling solvent (see Chapter 2). These compounds have structures in which the rare earth element is sandwiched between two phthalocyanine rings, e.g. zirconium bisphthalocyanine (1.92 M = Zr) and lutetium bisphthalocyanine (192 M = Lu), the latter protonated on one of the meso N atoms to balance the charge. 

Rare-earth bisphthalocyaninates, especially LuPc2, are one of the important objects of intense investigation because of their electrochemical (electrochromic effect), electrical, and optical properties. The ball-type four t-butyl-calix[4]arene bridged double decker lutetium(III) and indium(III) Pcs have also been prepared, Fig. 3 [42],... 

Bisphthalocyanines based on rare earth metals lutenium (45j) and thulium (45k) were studied as early as 1990.[267] These compounds had a field-effect mobility of 10 cm V- s- under vacuum, but the electronic properties degraded rapidly upon exposure to ambient conditions. 

Rodriguez, M.L., R. Aroca, and J.A. DeSaja (1992). Electrochromic properties of Langmuir-Blodgett films of bisphthalocyanine complexes of rare earth elements. Chem. Matter 4,1017. 

Electrochromic effects have been observed for LB films of rare-earth-substituted phthalocyanines (2), with X = Yb, Pt [82]. In general, the compressed monolayers are only found to be sufficiently stable when dimers of the type YbPc2 are used. However, electrochromic switching is only observed when alternative Y-type layers of the dimer are deposited with fatty acids. It has been established that a self-reorganization mechanism of the bisphthalocyanines operates, and that the alkyl-chain length of the acid can significantly affect the switching mechanism. For example, if the chain contains fewer than 20 carbon atoms, the electrochromic process is not impeded if 20 or 21 carbon atoms are involved, the... 

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