Functionalised tetraheterofulvalenes for conducting Landmuir-Blodgett films and charge-transfer complexes
The tetrathiafulvalene (TTF) mono-anion route to functionalised derivatives has been extended to lead to new materials for charge-transfer (CT) complexes. New improved routes have been established towards halogenated and chalcogenated TTF derivatives from the TTF anion (23). Highly conducting complexes with TCNQ (1) have been obtained from 4-chloro- (30) and 4-bromotetrathiafulvalene (32). X-Ray studies of ethylenediseleno-TTF (44) and bis(tetrathiafulvalenyl)sulphide (59) have revealed novel structural features. New long chain TTF materials have also been synthesised, suitable for Langmuir-Blodgett (LB) films, using TTF anion and 1,3-dithiole cross-coupling methodologies. Amphiphiles bearing highly functionalised groups, both adjacent to the TTF ring and in the side chain, have been synthesised, and LB films have been formed from some of these materials. Iodine doping of the films has provided conducting mixed- valence systems. Monofunctionalised tetraselenafulvalenes (TSF) have been synthesised from the TSF tetra-anion (118) and a range of acid chlorides, to yield the corresponding ketones. X-Ray crystal structure analysis of 4-acetyltetraselenafulvalene (123), has unequivocally proven that under these reaction conditions the TSF unit stays intact.