Aryl ester dendrimers incorporating tetrathiafulvalene units: convergent synthesis, electrochemistry and charge-transfer properties

The convergent synthesis of a range of aryl ester dendrimers with peripheral tetrathiafulvalene (TTF) units is reported. 4-( Hydroxymethyl)-TTF and 4,5-(2-hydroxymethylpropane-1,3-diyldithio)-TTF have been used as the starting TTF reagents. The core reagents are benzene-1,3,5-tricarbonyl trichloride, terephthaloyl chloride, biphenyl-4-4'-dicarbonyl chloride and 4,4'-oxybis(benzenecarbonyl chloride). Dendrimers comprising up to 12 TTF units have been characterised by elemental analysis, plasma desorption mass spectrometry, H-1 NMR spectroscopy and solution electrochemistry. Cyclic voltammetry (CV) and ultra microelectrode CV studies show that the TTF dendrimers display nearly ideal redox behaviour for the TTF system with no significant interaction between the TTF units. Thin layer cyclic voltammetric studies show that all the TTF units of these systems undergo two, single-electron oxidations. The dendrimers form charge-transfer complexes upon reaction with iodine in solution. Intermolecular interactions of the TTF radical cations are observed in the UV-VIS spectra of some of the oxidised derivatives.