Synthese et Proprietes Redox des ?-Donneurs Mesogenes

Abstract

In the sequence of previous work on 2,2′,6.6′-titraaryl-4,4′-bipyrannylidbne and their sulfur analogs^1,2 we report the synthesis (Scheme 1 and 2) and redox properties of heterocycles having long chain substituents. Introduction of four alkyl groups C_n H_2n+1 in the para position of the phenyl groups leads to π-donors having mesomorphic (disco-like) properties (n > 9). In contrast, the presence of alkyloxy substituents leads only to mesomorphic species when the heteroatom is S but not O (n ≥ 12). All new donors give stable 1 :1 charge transfer complex with TCNQ, several of them having also mesomorphic properties.