ANALYSIS OF THE POLARIZATION DISTRIBUTION IN A POLAR PERHYDROTRIPHENYLENE INCLUSION COMPOUND BY SCANNING PYROELECTRIC MICROSCOPY

The polarization distribution in a polar perhydrotriphenylene (PHTP) i nclusion compound has been studied by scanning pyroelectric microscopy . Measurements have been performed on solution-grown crystals of PHTP- AD (AD: acceptor(A) and donor (D) disubstituted linear chromophores). The AD guest molecules form aligned dipole chains within the parallel channels created by the honeycomb-type host lattice of PHTP. Along the channel direction we found a 180 degrees twinned macrodomain state wi th wedge-shaped domain boundaries adjacent to the middle of the needle -shaped crystals. In each domain the polarization is nearly constant, which implies that the majority of molecular dipoles are aligned paral lel. This agrees well with predictions arising from the application of Markov's theory of stochastic processes, which explains the occurrenc e of polar domains due to a mechanism of dipole incorporation driven b y the difference in the -A...A- and -D...D- intermolecular interaction energies.