Crystallographic constants for some high-density β-phthalocyanines

Abstract

The authors of a number of papers1 dealing with the problem of electrical conduction in the various phthalocyanines assume that the compounds studied were the high-temperature /?-polymorphs having the same unit cell dimensions as those given by Robertson2 (Table 1).One of the present authors (P.E.F.) and his colleagues accepted these data until H. Struve observed that the activation energy for electrical Ref.-Present work (by S.C.S.).conduction in cobalt phthalocyanine was affected by thermal annealing.3This has since been shown to be due to electrode and surface phenomena, but density measurements were carried out to check for possible phase changes.A density-gradient column4 consisting of mixtures of 1,2-dibromoethane and carbon tetrachloride with calibrated glass markers5 was used to measure the densities of batches of single crystal sections prepared by vapour-phase sublimation.1Although