Association and orientation of copper(II) tetra-t-butylphthalocyaninate in multilayer Langmuir–Blodgett films as determined by electron paramagnetic resonance spectroscopy
Abstract
E.s.r. spectra obtained at 20 or 25 K, electronic absorption spectra measured at ambient temperature, and vapour-phase osmometry show that copper tetra-t-butylphthalocyaninate (1) is associated in dilute solutions in dichloromethane but unassociated in toluene. The corresponding spectra within single- and multi-component Langmuir–Blodgett films on silica slides are also reported. Films containing complex (1) either alone or admixed with eicosanoic acid gave spectra characteristic of the associated material. However, a three-component film containing (1), tetra-t-butylphthalocyanine (2), and eicosanoic acid (ratio 5 : 50 : 400) gave an e.s.r. spectrum showing hyperfine and superhyperfine structure. The orientational dependence of the e.s.r. spectrum was investigated and reveals that the molecules of (1) are aligned with the plane of the ring at 80 ± 10° to the substrate surface. Some orientational disorder is also present and can be detected in the g∥ region.
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