Structure and thermal properties of crystals. V. Thermal expansion of phthalocyanines and porphins

Abstract

Measurements have been made on the changes in lattice spacing of various phthalocyanines, over a range of temperatures from 90 to 600° K. Rough visual estimates have also been obtained of changes in the intensities of reflexions with rise in temperature. The molecular movements in the crystals have been calculated from the experimental data. Attention is drawn to the difference in behaviour of hydrogen and platinum phthalocyanines, which is probably due to the increased space required by the platinum atoms as the temperature rises, compared with the hydrogen in hydrogen phthalocyanine. Apparatus described includes a new design of furnace, suitable for use with various X-ray cameras for single crystal work, and a moving film oscillation camera, which uses the multiple exposure principle to determine small changes in lattice spacing with high relative accuracy.