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

Abstract

Unsymmetrically substituted tetrathiafulvalene derivatives containing hydroxy group(s) on side-chain(s) have been synthesized from cyano precursors via either a cross-coupling reaction or a Wittig-type condensation. As deduced from cyclic voltammetry data, the electron donor properties of the obtained 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 electrocrystallization and charge transfer complexes have been prepared chemically by using TCNQ as an electron acceptor. The electrical conductivity of these phases ranges from 3610 22 to 7610 27 S cm 21 which is consistent with their structural features. X-Ray structural analysis of three of the radical cation salts with monovalent closed-shell anions (Br 2 , ClO 42 ) indicates a 1 : 1 stoichiometry which implies that, in each case, the donor has been oxidized to the D z state. In the same way, a crystal structure made of stacks where the donor and the acceptor molecules alternate has been found for a charge transfer complex between TCNQ and a donor derived from EDTTTF. The crystal structure of one of the donors indicates that the ¯exibility of the hydroxylated side chains appears as a favourable feature for the formation of hydrogen bonds.{Crystal data and structure determination details for 2a are available as supplementary data. For direct electronic access see http:// www.rsc.org/suppdata/jm/b0/b003009k/ {Compounds 2a, b and 4a, b have also been named as 2,3,6,7tetrasubstituted tetrathiafulvalenes.

Dimensionality and Electrical Properties in Organic Synthetic Metals—Current Results through Selected Recent Examples

“…Unfortunately, the hydroxylated TTF such as 1, 2, 6 and 7 (26)(27)30) exhibited low values of conductivity due to a complete oxidation of the donor and/or a structural disorder initiated by the more or less long side chain bearing the hydroxyl groups of the donor. However in this family of compounds, a promising result was recently depicted with TTF 8a and 8b containing an amide function.…”

“…This is despite the fact that donors such as 4 (28) and the polyhydroxylated TTF 5 containing long side chains (29) give rise to crystal structures displaying quite strong N-HyO hydrogen bonds and uniform close stacking of the TTF rings respectively. More recently the crystal structure of semi-conducting salts of 1:1 stoichiometry 6 Á Br and 7 Á ClO 4 (two phases) obtained from donors 6 and 7 containing respectively one and two OH groups on a flexible side chain was studied (30). In each …”

Synthesis and properties of tetrathiafulvalene-porphyrin assemblies

“…Compounds 1-3 and 5 were synthesized according to the reported procedures [21,22]. 5,15-Bis(4-aminophenyl)-10,20-diphenylporphyrin (6) To a stirred solution of 4 (0.71 g, 1 mmol) in 38% HCl (100 mL) was added SnCl 2 (1.28 g, 6 mmol).…”

Donor–acceptor complex of a new bis-TTF donor containing a pyridine diester spacer with TCNQ as the acceptor: a disappointing system

“…It is now clearly established that the metallic state observed in organic conducting materials of the TTF type (TTF is tetrathiafulvalene) (Fabre, 2002) can be strongly stabilized by increasing their structural and electronic dimensionality (Williams et al, 1992;Fabre, 2000). Such a result can be attained by introducing, on the TTF ring, a functional group able to provide supplementary molecular interactions (Batsanov et al, 1995;Heuzé et al, 2000;Legros et al, 2000;Lorcy et al, 2009). In the past decade, extended TTF systems have received much attention as building blocks potentially able to enhance the dimensionality in derived conducting materials (Bryce, 1995;Iyoda, 2004;Lorcy et al, 2009).…”

“…Most of the DA compounds that crystallize with an alternate stacking of the D and A entities exhibit low electrical conductivity (Cassoux & Valade, 1996). Examples with TCNQ as the acceptor are given by Chasseau et al (1982), Imaeda et al (1991) and Legros et al (2000). In addition, the lack of efficient overlap between the molecules of the stacks is another factor unfavourable to electronic delocalization.…”