X‐ray Diffraction Studies on the Molecular Semiconductors Based on the Charge‐Transfer Complexes of Some Substituted Phenothiazines with Iodine

Abstract

AbstractThe powder X‐ray diffraction data on some molecular semiconductors based on the charge transfer complexes of three substituted phenothiazines viz., phenothiazine (PTZ), 2‐chlorophenothiazine (CPZ), and 2‐(trifluoromethyl)phenothiazine (TPZ) with molecular iodine have been reported in this paper. The indexing of the data has been done by Ito's method. All the complexes have been found to have orthorhombic crystal structures. The lattice parameters for the individual complexes are as follows: equation image .These results indicate that the segregated stacking of mixed valence with neutral and cationic donor moieties and polymeric iodide species, two pentaiodides linked with one trüodide forming a staircase delocalized structure, are present in these complexes. This may be possibly the reason for high electrical conductivity of these complexes. However, the charge transfer complexes of iodine with 2‐acetylphenothiazine (APZ), N‐acetylphenothiazine (NAPZ) and N‐benzoylphenothiazine (NBPZ) give no diffraction patterns indicating that the molecular semiconductors based on these complexes exist in amorphous form. This is further supported by very low electrical conductivities of these complexes. This structural information is quite useful in discussing the electronic properties of this class of molecular semiconductors.