Molecular image of copper phthalocyanine

Abstract

SUMMARY The structure of copper phthalocyanine has been studied by high resolution transmission electron microscopy (TEM). To reduce radiation damage, the technique of minimal beam exposure has been used together with X‐ray film for recording the image. This resulted in very noisy micrographs but optical averaging clearly revealed the molecular shape of the copper phthalocyanine, and also showed that a slight discrepancy exists between the averaged image, and the model structure which had been assumed to be isomorphous with platinum phthalocyanine.

Molecular images of the hydrocarbon C22H12– anthanthrene

“…The only molecular images reported previously have been the highly radiation-resistant chlorinated copper phthalocyanine (Uyeda, Kobayashi, Suito, Harada & Watanabe, 1972) and our studies on non-chlorinated copper phthalocyanine (Murata, Fryer & Baird, 1976). This definition of molecular images excludes the biological molecules that are of comparable or greater sensitivity to radiation, but which are normally hydrogen-bonded structures and comprise many thousands of atoms.…”

“…Small improvements in the utilization factor might be possible but of little value. The contrast can be improved by spatial averaging over a large number of periodic unit cells (McLachlan, 1958;Kuo & Glaeser, 1975;Murata, Fryer & Baird, 1976). In the limit, of course, this is the process of X-ray and electron diffraction, but for structural information for small regions of the specimen, this method is of considerable value, and using a simple optical method with a photographic enlarger considerable improvements in contrast can be obtained.…”

The effect of crystal bending on direct phasing of electron diffraction data from cytosine

“…Practically speaking, this demands an epitaxial crystal growth for specimen preparation, since normal growth from solution generally ensures that the longest unit-cell axes will be perpendicular to the largest crystal faces (Jensen, 1970). Fortunately, the appropriate epitaxial growth conditions have been realized for various aromatic systems including phthalocyanines (Uyeda, Kobayashi, Suito, Harada & Watanabe, 1972;Murata, Fryer & Baird, 1976), fused ring compounds (Fryer, 1978(Fryer, , 1979, and linear polymers (Wittman & Manley, 1978;Wittman & Lotz, 1981). High-resolution, low-dose electron microscopy on these materials has already shown the outline of the molecular images.…”

Molecular images of thin-film polymorphs and phase transformations in metal-free phthalocyanine

“…Three polymorphs of phthalocyanine were reported by Susich (1950) and differentiated by X-ray powder photographs but a more detailed examination was carried out by Ebert & Gottlieb (1951) who detected only two polymorphs using both X-ray and infrared absorption techniques. Karasek & Decius (1952) prepared the a-phthalocyanine (metastable form) by evaporation on to polished NaCI maintained below 473 K in a vacuum of 7-6 x 10 -8 Pa. (Murata, Fryer & Baird, 1976a). A high-pressure phase of phthalocyanine was isolated by Kirk (1967) who found a reversible transformation occurred at 7.2 x 10 -2 Pa giving a monoclinic structure ofa = 23-7, b = 3-91, c = 16-1 A and p = 130 ° whilst Vidadi, Chistyakov & Rosenshtein (1969) detected a change in the dielectric constant of evaporated thin films exposed to air at room temperature.…”

“…The radiation dose for total disruption of phthalocyanine has been measured as 3-7 x 1011 Bq s -~ mm -2 at 60 keV (Reimer, 1960) which is approximately ten times less than the dose for the copper derivative that has been studied (Murata, Fryer & Baird, 1976a). This stability is comparable with that of naphthacene and hydrocarbons of this order of stability have been imaged at 100 keV (Fryer, 1978).…”