DIRECT OBSERVATION OF MOLECULAR IMAGES OF LANTHANIDE PHTHALOCYANINES .1. MOLECULAR, CRYSTAL, AND TWIN STRUCTURES

Lanthanide phthalocyanine (LnPc2H:Ln = Nd, Tb, Er, Tm, Yb, and Lu) thin films prepared epitaxially on KCl and NaCl crystals have been studied at the molecular level by means of high-resolution electron microscopy. Both tetragonal and orthorhombic structures have been found. It is revealed that the interaction between substrates and molecules, the existence of geometric isomers, the anisotropy of molecular shapes, and the intermolecular forces play important roles in molecular stacking. Twins occur abundantly in the films growing on KCl and the twin relationship can be understood from the geometry of molecular shapes and their arrangement. It is suggested that the relative angle between two phthalocyanine ligands of a LnPc2H molecule may vary within a limited angle range.