SYNTHESIS AND REDOX PROPERTIES OF MESOMORPHIC PI-DONORS

In the sequence of previous work on 2,2 prime ,6,6 prime -tetraaryl-4,4 prime -bipyrannylidene and their sulfur analogs, the authors report the synthesis (Scheme 1 and 2) and redox properties of heterocycles having long chain substituents. Introduction of four alkyl groups C//nH//2//n// plus //1 in the para position of the phenyl groups leads to pi -donors having mesomorphic (disco-like) properties (n greater than 9). In contrast, the presence of alkyloxy substituents leads only to mesomorphic species when the heteroatom is S but not O (n greater than equivalent to 12). All new donors give stable 1:1 charge transfer complex with TCNQ, several of them having also mesomorphic properties.