Synthesis and study of radical cation salts and TCNQ charge transfer complexes of a series of tetrathiafulvalenes (TTF) substituted by one or two hydroxylated side chain(s): -SCH2CH2OH

Unsymmetrically substituted tetrathiafulvalene derivatives containing hydro xy group(s) on side-chain(s) have been synthesized from cyano precursors vi a either a cross-coupling reaction or a Wittig-type condensation. As deduce d from cyclic voltammetry data, the electron donor properties of the obtain ed compounds have been found to be similar to those of BEDTTTF. A series of radical cation salts derived from these donors has been obtained by electr ocrystallization and charge transfer complexes have been prepared chemicall y by using TCNQ as an electron acceptor. The electrical conductivity of the se phases ranges from 3 x 10(-2) to 7 x 10(-7) S cm(-1) which is consistent with their structural features. X-Ray structural analysis of three of the radical cation salts with monovalent closed-shell anions (Br-, ClO4-) indic ates a 1:1 stoichiometry which implies that, in each case, the donor has be en oxidized to the D+ state. In the same way, a crystal structure made of s tacks where the donor and the acceptor molecules alternate has been found f or a charge transfer complex between TCNQ and a donor derived from EDTTTF. The crystal structure of one of the donors indicates that the flexibility o f the hydroxylated side chains appears as a favourable feature for the form ation of hydrogen bonds.