Synthesis and properties of novel unsymmetrical donor molecules containing p-acetoxy- or p-hydroxyphenyl units

Article abstract of DOI:10.3390/11100776

We report the synthesis and properties of eight new tetrathiafulvalene (TTF) derivatives containing two different functionalities, prepared with the aim of obtaining stable organic materials. The four acetoxyphenyl- and four hydroxyphenyl TTFs were synthe

Full text of DOI:10.3390/11100776

Molecules 2006, 11, 776-785
molecules
ISSN 1420-3049
http://www.mdpi.org
Full Paper
Synthesis and Properties of Novel Unsymmetrical Donor
Molecules Containing p-Acetoxy- or p-Hydroxyphenyl Units
Lakhemici Kaboub, Slimane Fradj and Abdelkrim Gouasmia*
Laboratoire des Matériaux Organiques et Hétérochimie, Département de Chimie, Université de
Tébessa, 12000 Tébessa, Algeria
* Author to whom correspondence should be addressed; E-mail: akgouasmia@mail.univ-tebessa.dz
Tel.: (+213)37490062, Fax: (+213)37490268
Received: 26 July 2006; in revised form: 17 September 2006 / Accepted: 10 October 2006 / Published:
21 October 2006
Abstract: We report the synthesis and properties of eight new tetrathiafulvalene (TTF)
derivatives containing two different functionalities, prepared with the aim of obtaining
stable organic materials. The four acetoxyphenyl- and four hydroxyphenyl TTFs were
synthesized via Wittig-type condensations. The electrochemical properties of these
redox-active molecules were studied by cyclic voltammetry. Charge transfer complexes
with tetracyanoquinodimethane (TCNQ) were prepared by chemical redox reactions. The
complexes have been proven to give conducting materials. The UV-VIS and IR spectra
of the TCNQ salts were recorded and used to characterize and estimate the degree of
charge transfer of these complexes.
Keywords: Tetratiafulvalene, voltammetry, organic materials, conductivity, degree of
charge transfer.
Introduction
Because of their exciting electroactive properties, organic tetrathiafulvalene (TTF) compounds are
the subject of much interest [1-3]. The most interesting of these systems is the salt formed between
TTF and tetracyanoquinodimethane (TCNQ), which displays metallic-like behavior over a wide
temperature range and exceptional electrical conductivity (σ max, 58 k = 104 S·cm-1) [4-6]. Most of the

Molecules 2006, 11
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prior work, however, has been devoted to the search for new TTF derivatives capable of giving salts
with higher electrical conductivity. Consequently, many changes were made to the parent TTF donor
leading, for example, to the synthesis of a wide variety of selenium derivatives, asymmetrically
substituted compounds, polychalcogenated TTFs, etc. In order to consolidate the asymmetrical
character of the donors, several tetrathiafulvalene derivatives containing different groups such as
nitronylnitroxide [7], 4,5-diformyl [8], aminomethyl [9] and hydroxymethyl [10] have been described.
They were found to be versatile starting new donors for the synthesis of new organic materials.
Recently, and proceeding from accessible conducting organic materials, we synthesized a series of
TTF derivatives containing peripheral selenium atoms and demonstrated their ability to form charge
transfer complexes and radical cation salts [11,12]. Within the framework of our interest in organic
materials we now describe in this paper the synthesis and properties of some new asymmetrical donors
containing acetoxyphenyl and hydroxyphenyl groups. These compounds have been investigated by
means of cyclic voltammetry. The electron donor properties of the various compounds obtained have
been found to be lower to those of TTF. Conducting charge transfer complexes are also presented. The
degree of charge transfer and molecular stacking were estimated by spectroscopic data.
Results and Discussion
Synthesis
We have synthesized p-acetoxyphenyltrimethyltetrathiafulvalene pAcPhTrMeTTF (5a) [13] by two
different methodologies. The first involved the condensation of 5-(p-acetoxyphenyl)-4-methyl-1,3-
dithiolium perchlorate with 4,5-dimethyl-1,3-dithiolium hexafluorophosphate in triethylamine to give
2-(4-acetoxyphenyl)-3,6,7-trimethyltetrathiafulvalene in 15% yield. The second route involved the
reaction of 2-diethoxyphosphinyl-4,5-dimethyl-1,3-dithiole with 5-(p-acetoxyphenyl)-4-methyl-1,3-
dithiole-2-ylidenepiperidinium tetrafluoroborate under Wittig-like conditions to form the target TTF
5a in 20% yield. Despite these poor yields, we nevertheless prepared the other asymmetrical
derivatives, that is 2-(4-acetoxyphenyl)-3-methyl-6,7-(propane-1,3-diyl)tetrathiafulvalene (5b), 2-(4-
acetoxy-phenyl)-3-methyl-6,7-(butane-1,4-diyl)tetrathiafulvalene (5c) and 2-(4-acetoxyphenyl)-3-
methyl-6,7-(buta-1,3-dien-1,4-diyl)tetrathiafulvalene (5d) applying the cross-coupling reaction [14] of
1,3-dithiole-2-methyl-selenoxonium salts with 1,3-dithiole-2-triphenylphosphonium salts.
Scheme 1. Synthesis of 2-methylseleno-1,3-dithiolium trifluoromethanesulfonate.
AcO
AcO
AcO
S
S
-
S
S
-
+
S
S
F3CSO3CH3
CH2Cl2
+
Se/NaBH4
Se
BF4
N
SeCH3, F3CSO3
AcOH
H3C
H3C
H3C
1
2
3
As shown in Scheme 1, treatment of 5-p-acetoxyphenyl-4-methyl-1,3-dithiole-2-ylidene-
piperidinium tetrafluoroborate (1) with sodium hydrogen selenide, prepared in situ from selenium and
sodium borohydride in ethanol at low temperature, followed by an aqueous work up, led to a good
yield (95 %) of the corresponding red 5-(p-acetoxyphenyl)-4-methyl-1,3-dithiole-2-selenone (2) [15].

Molecules 2006, 11
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2-Methylseleno-5-(p-acetoxyphenyl)-4-methyl-1,3-dithiolium trifluoromethanesulfonate (3) [16] was
obtained in good yield (95 %) by alkylation of 2 with triflate.
The phosphonium salts 4a-d [16] were dissolved in dry acetonitrile together with one equivalent of
selenoxonium salt 3 (Scheme 2). The mixtures were stirred under nitrogen and an excess of
triethylamine was added slowly, followed by a further 3 h of stirring at room temperature. The solvent
was evaporated and the crude products were dissolved in chloroform, washed with water and dried.
Evaporation of chloroform, followed by purification using chromatography on silica with benzene as
eluent and recrystallization from hexane gave pAcPhTrMeTTF 5a, pAcPhMeCpTTF 5b,
pAcPhMeChTTF 5c and pAcPhMeBzTTF 5d as red crystals in 15-33 % yields.
Scheme 2. Classic Synthetic Route for the Preparation of pAcPhTTF Derivatives
AcO
AcO
+
-
R
R
R
-
S
S
S
S
PPh3 PF6
S
S
S
S
+
Et3N
THF
SeCH3, F3CSO3
+
H
H3C
H3C
R
3
4 a-d
5a R = CH3 , 5b R-R = (CH2)3
5c R-R = (CH2)4 , 5d R-R = (CH= CH)2
Deacetylation of these asymmetrically p-acetoxyphenyltetrathiafulvalenes with hydrazine in
methanol (Scheme 3) yielded the desired p-hydroxyphenyltetrathiafulvalenes pHyPhTrMeTTF 6a,
pHyPhMeCpTTF 6b, pHyPhMeChTTF 6c and pHyPhMeBzTTF 6d as red crystals in 85-90 % yields.
Scheme 3. Efficient Synthetic Route for the Desacetylisation of TTF Derivatives
HO
AcO
R
R
S
S
S
S
N2H4
S
S
S
S
MeOH
H3C
R
H3C
R
5a-d
6a-d
Electrochemical studies
The oxidation potentials of the donor molecules were determined by cyclic voltammetry.
Measurements were performed under nitrogen at room temperature using a glassy carbon working
electrode, a Pt counter electrode and a standard calomel electrode (SCE) as reference, with
tetrabutylammonium perchlorate (n-Bu4NClO4, 0.1 M) in dry acetonitrile and 1,2,2-trichloroethane, as
supporting electrolyte. A scan rate of 100 mVs-1 was used. The results are reported in Table 1.
All TTFs showed two pairs of reversible waves. These results indicate that the presence of the
acetoxy CH3CO- and hydroxy -OH functions relatively far away from the TTF core on the side C6H4-
chain, has only a very weak influence on the redox potential values of the compounds 5a-d and 6a-d.
It is also noteworthy that the benzo -C6H4- (buta-1,3-dien-1,4-diyl) grouping exerts withdrawing
effects, as indicated by the observed E ox1 and E11/2 values in acetonitrile solution for 5d (0.48, 0.45 V)

Molecules 2006, 11
779
and 6d (0.46, 0.43 V), respectively. Similar observations can be made about the other series of
compounds 5a-c and 6a-c.
Table 1. Redox potentials and KSEM data of 5a-d and 6a-d.
Acetonitrile
Eox1 Eox2 ∆E ox E1 E2
1,1,2-Trichloroethane
E2
Donor
∆E1/2 a∆E1/2 KSEM Eox1 E ox2 ∆E ox E1
∆E1/2
1/2
1/2
1/2
1/2
5a
0.30 0.64 0.34 0.28 0.62 0.34
0.32 0.80 0.48 0.28 0.67 0.39
0.32 0.66 0.34 0.29 0.64 0.35
0.48 0.82 0.34 0.45 0.77 0.32
0.30 0.64 0.34 0.26 0.62 0.36
0.30 0.64 0.34 0.28 0.61 0.33
0.34 0.70 0.36 0.31 0.65 0.34
0.46 0.80 0.34 0.43 0.78 0.35
0.37 0.74 0.37 0.32 0.69 0.37
0.08
0.08
0.09
0.25
0.06
0.08
0.11
0.23
0.12
0.04
5.8·105 0.42 0.86 0.44
39·105 0.46 0.90 0.44
8.5·105 0.46 0.92 0.46
2.6·105 0.62 1.08 0.46
13·105 0.36 0.82 0.46
3.9·105 0.38 0.84 0.46
5.7·105 0.36 0.82 0.46
8.5·105 0.54 1.00 0.46
1.9·105 0.82 1.08 0.26
0.34 0.78 0.44
0.38 0.81 0.43
0.33 0.79 0.46
0.53 0.98 0.45
0.29 0.73 0.44
0.32 0.74 0.42
0.31 0.75 0.44
0.49 0.92 0.43
5b
5c
5d
6a
6b
6c
6d
TTF
0.58 1.0
0.42
-
TMTTF 0.29 0.65 0.36 0.24 0.60 0.36
13·105
-
-
-
-
-
*
a∆E1/2 = E1 -*E11/2; E1 = E1 ½ red (TCNQ) = 0.2 V ; E2 ½ red (TCNQ) = - 0.36 V.
½
½
Due to the well known donating effect exerted by the methyl, propane-1,3-diyl and butane-1,4-
diyl substituents these TTF derivatives are better electron donors than the parent TTF taken as a
reference. On the other hand, the ∆E 1/2 values, in ACN, of the majority of TTFs are smaller than those
of the unsubstituted parent compound TTF (0.37 V), which suggests a decrease in the onsite
coulombic repulsion in the dication by delocalisation of two positive charges over the whole molecule.
In TCE as the solvent, the π- ability of all compounds appears exceptionally strong, since for all of
them, the ∆ EOX is markedly higher than of the parent TTF (0.28 V). Those complexes have |E1
-
1/2(D)
E11/2(A)| values and favor the partial charge transfer. These results compare well with those of Wheland
[17] and Torrance [18].
The thermodynamic stability of radical cations was determined from the difference in potentials of
the corresponding radical cation and dication using the equation ∆E = E1 – E2 = 0.059 log KSEM
1/2
1/2
(Table 1) where KSEM is the equilibrium constant in equation: D + D2+
2 D.+ . For electron donor
TTF compounds, the thermodynamic stability of the cation radical diminishes in the following order:
5b > 6a > 5c = 6d > 5a = 6c > 6b > 5d, due to a decrease in intermolecular coulombic repulsion.
Electrical conductivity and activation energies of charge transfer complexes
Complexation of the donors 5a-d and 6a-d with 7,7,8,8-tetracyanoquinodimethane in hot
acetonitrile solution gave the corresponding complexes. Most of the solids were isolated in
polycrystalline or powder forms. Electrical conductivity was only measured on compressed pellets at
room temperature using a two probe technique. The results are reported in Table 2. All TCNQ
complexes exhibited a conductivity higher than 0.5 Scm-1; the 5d-TCNQ sample displayed
semiconducting behavior, with conductivity less than 10-6 Scm-1. The 6-TCNQ salts (0.5-5.5 Scm-1)
exhibits higher conductivity than that of the other 5-TCNQ salts (0.5 – 3.5 10-6 Scm-1).

Molecules 2006, 11
780
A p-hydroxyphenyl group attached to a TTF framework seems to increase the conductivity,
compared with the corresponding p-acetoxyphenyl group. For the TCNQ complexes with
comparatively higher electrical conductivities the Ea values were small (0.09-0.15 eV). On the other
hand, an insulating salt such as 5d-TCNQ had considerably higher activation energy (0.46 eV).
Table 2. Electrical conductivity and activation energies of charge transfer complexes.
Complex
5a-TCNQ
5b-TCNQ
5c-TCNQ
5d-TCNQ
σRT (Scm-1) Ea(eV)
Complex
6a-TCNQ
6b-TCNQ
6c-TCNQ
6d-TCNQ
σRT (Scm-1) Ea(eV)
2
0.5
0.116
0.152
0.122
0.462
3.5
2.0
5.5
0.5
0.100
0.116
0.090
0.152
1.5
3.5 10-6
IR Spectroscopic studies
It is established that the complexes of type TTF-TCNQ have to satisfy two conditions to give a
conductor. The first requires the presence of a crystal structure composed of regular segregated stacks
…DDD-AAA… of donors and acceptors [19]; while the second is a partial electron transfer (0<ρ<1)
between these two species. Any of mixed stack "sandwich" structures …DAD-DAD… of the salt or
the absence of a charge transfer (molecular complex) or a complete charge transfer (ionic complex)
lead to an insulating material [20, 21].
Figure 1. The correlation between the νCN and ρ.
1
0.8
0.6
0.4
0.2
0
2180
2190
2200
2210
2220
2230
Frequency of vibration of the CNgroup / cm-1
Due to the lack of monocrystals, various authors were able to estimate the rate of charge transfer of
this type of complex from different techniques [22] and in particular from the IR spectra [23, 24].
Based on the relation between the frequency of vibration of the CN group and the degree of charge
transfer for reference compounds such as TCNQ0 (νCN = 2227 cm-1, ρ = 0 e-/molecule), TCNQ-K+
(2183 cm-1, 1), TTF-TCNQ (2204 cm-1, 0.59), HMTTF-TCNQ (2195 cm-1, 0.72), TMTTF-TCNQ
(2200 cm-1, 0.65), TMTSF-TCNQ (red) (2217 cm-1, 0.23), etc. We were able to draw a ρ = f (νCN)
straight line, which corresponds to the correlation between the vibration frequencies of the CN group
and the degree of charge transfer for different TTFs. The curve equation is y = -0.0228x + 50.71. The
coefficient of determination is R2 = 0.9933 (Figure 1).

Molecules 2006, 11
781
We recorded the IR spectra of all complexes prepared in the 2100 and 2250 cm-1 range and we
obtained the vibration frequency of the CN group for each complex. The νCN frequency was then used
on the calibration ρ = f (νCN) curve to determine the approximate value of the degree of charge transfer
(ρ). The results are reported in Table 3.
Table 3. Degree of charge transfer of TCNQ complexes.
Complex
5a-TCNQ
5b-TCNQ
5c-TCNQ
5d-TCNQ
νCN (cm-1)
2198
ρ (e-/mole)
0.69
Complex
6a-TCNQ
6b-TCNQ
6c-TCNQ
6d-TCNQ
νCN (cm-1)
2211
ρ (e-/mole)
0.37
2200
0.63
2214
0.30
2196
0.74
2210
0.40
2208
0.45
2194
0.79
It appears that the conducting materials: 5a-c-TCNQ, and 6a-d-TCNQ, present a partial degree of
charge transfer in the 0.30 to 0.79 e-/molecule range. These values are comparable to those of known
conductors, such as Cu(PC)I (0.33), TTF-TCNQ (0.59) and HMTTF-TCNQ (0.72) [24]. Considering
these results, it is reasonable to propose that the conducting charge transfer complexes studied here
possess a segregated stacking structure.
As for the nonconducting 5d-TCNQ, the value of the degree of charge transfer is about 0.43 e-/
molecule. This value is in a range that would favor a metallic behavior for this salt. Since it is
semiconducting, we are lead to believe that the requirement regarding the stacking of the molecules is
not met. Several explanations for this behavior might be a mixed stack (sandwich) structure, a large
separation between stacked donors, the presence of structural disorder [19], etc. When a comparison
was made between the E11/2 values of the hydroxy donors 6a-d and ρ values of the TCNQ complexes,
it was found that the degree of electron transfer from the donor to TCNQ decreases in the TCNQ
complex, as the E11/2 value of the donor becomes smaller.
The electrical results are consistent with those of the electronic spectra of the complexes in KBr
pellets. The high conductivity of the conducting complexes was expected from both the black shiny
crystals and the broad band observed in the FTIR spectrum at about 2500 cm-1. This band is generally
present in all the conducting charge transfer complexes of TTF-TCNQ [19]. The other complex, which
is insulator, is slightly colored and the band at 2500 cm-1 is not observed in the IR spectrum. The CT
band is probably shifted to higher frequencies as it is typical in such semiconducting complexes [19].
Conclusions
Although the Wittig-type synthetic strategy described in this paper affords low overall yields we
have prepared two series of new asymmetric TTF derivatives containing p-acetoxyphenyl and
p-hydroxyphenyl groups. The side chains that we introduced preserve the electron donating character
of these TTFs, as shown by cyclic votammetry. Several salts showing comparatively high room
temperature conductivity were obtained. We have discussed the origin of the semiconducting behavior
of some of the TTF derivatives and indicated that the semiconducting salts exhibited a charge transfer
band at higher energy, suggesting stronger coulombic repulsions. The possibility of producing new
cation-radical salts in these series and the X- ray structural details [12], are under investigation.

Molecules 2006, 11
Experimental
General
782
NMR spectra were recorded on a Bruker AC 250 instrument. FAB mass spectra were recorded on
a JOEL JMS-DX 300 spectrometer. IR spectra were recorded at 0.5 cm-1 resolution on an Equinox 55
instrument. Melting points were measured on a Buchi apparatus. Cyclic voltammetry measurements
were carried out on a PAR-273 potentiostat/galvanostat. All reagents were of commercial quality and
solvents were dried, were necessary, using standard procedures. All reactions were performed under an
inert atmosphere of nitrogen. THF was distilled from sodium/benzophenone immediately prior to use
in pre-dried glassware.
5-(p-Acetoxyphenyl)-4-methyl-1,3-dithiole-2-selenone (2)
Black powdered selenium (2.8 g, 35.37 mmol) was added in one portion with magnetic stirring at 0
°C under argon to a solution of sodium borohydride (7.7 g, 70.74 mmol) in ethanol (40 mL). A
vigorous reaction with considerable foaming occurred immediately and the selenium was consumed in
less than 30 min. The virtually colorless solution of NaHSe which resulted was ready for use without
further treatment. After cooling of the solution acetic acid (2 mL, 35.37 mmol) and 5-p-acetoxyphenyl-
4-methyl-1,3-dithiole-2-ylidenepiperidinium tetrafluoroborate (1, 15 g, 35.37 mmol) were added and
the reaction mixture was allowed to stand at room temperature for ca. 2 h. The ethanol was diluted to
100% with deoxygenated ice water and the red solid filtered, washed with water, dried under vacuum
and chromatographed (silica gel, CHCl3). Recrystallization of the product from heptane gave 2 (11.14
1
g, 95% yield) as red orange crystals; mp 143-144 °C; H-NMR (CDCl3) δ 2.28 (s, 3H), 2.33 (s, 3H),
7.28 (m, 4H).
2-Methylseleno-5-(p-acetoxyphenyl)-4-methyl-1,3-dithiolium trifluoromethane sulfonate (3)
A suspension of 5-(p-acetoxyphenyl)-4-methyl-1,3-dithiole-2-selenone (11.06 g, 33.62 mmol) in
dry methylene chloride (50 mL) was treated with methyl triflate (4.8 mL, 38.4 mmol). The mixture
was stirred under nitrogen for 4 h. A layer of dry ether (150 mL) was added. The deep reddish-orange
salt 3 was filtered after 24 h, washed with more dry ether, and dried. Yield: 16 g (95 %); mp 148-149
°C; 1H-NMR (CDCl3): δ 2.65 (s, 3H), 3.03 (s, 3H), 3.39 (s, 3H), 7.23 (m, 4H).
2-(4-Acetoxyphenyl)-3-methyl-6,7-dialkyl tetrathiafulvalenes 5a-d
A solution of 2-methylseleno-5-(p-acetoxyphenyl)-4-methyl-1,3-dithiolium trifluoromethane-
sulfonate (3, 4g, 8 mmol) and 4,5-dialkyl-1,3-dithiole-2-triphenylphosphonium (8 mmol) in
tetrahydro-furan (80 mL) was treated with triethylamine (25 mL) at room temperature under nitrogen.
After the reaction mixture was stirred for 4h, the solvent was evaporated under vacuum. The residue
was purified by column chromatography on silica gel with benzene as the eluent. The product was
purified by recrystallization from heptane to afford 5a-d.

Molecules 2006, 11
783
1
p-Acetoxyphenyltrimethyltetrathiafulvalene (5a). Yield: 30 %; mp: 220-221 °C; H-NMR (CDCl3): δ
13
1.96 (s, 6H), 2.04 (s, 3H), 2.32 (s, 3H), 7.12 (d, J = 8.6 Hz, 2H), 7.39 (d, J = 8.6 Hz, 2H); C-NMR
(CDCl3): δ 14.5, 15.7, 21.9, 107.4, 109.8, 122.6, 123.6, 123.7, 126.4, 127.6, 130.9, 151.1, 170.0; IR
(KBr, cm-1): 3050, 2900, 1750, 1490, 1430, 1200, 690; MS (FAB) m/z: 380 [M]+; Anal. Calc. for
C17H16O2S4: C, 53.68; H, 4.21; S, 33.68. Found: C, 53.76; H, 4.24; S, 33.20.
2-(4-Acetoxyphenyl)-3-methyl-6,7-(propane-1,3-diyl)tetrathiafulvalene (5b). Yield: 15 %; mp: 165-
1
166 °C; H-NMR (CDCl3): δ 2.05 (m, 2H), 2.18 (s, 3H), 2.32 (s, 3H), 2.41 (m, 4H), 7.11 (d, J = 8.6
13
Hz, 2H), 7.38 (d, J = 8.6 Hz, 2H); C-NMR (CDCl3): δ 14.9, 21.1, 27.6, 30.1, 116.8, 121.8, 125.4,
126.5, 130.2, 133.1, 133.2, 150.4, 169.3; IR (KBr, cm-1): 3030, 2920, 1740, 1500, 1200, 650; MS
(FAB) m/z: 392 [M]+; Anal. Calc. for C18H16O2S4: C, 55.10; H, 4.0; S, 32.65. Found: C, 55.23; H,
4.02; S, 32.72.
2-(4-Acetoxyphenyl)-3-methyl-6,7-(butane-1,4-diyl)tetrathiafulvalene (5c). Yield: 33 %; mp: 180-181
°C; 1H-NMR (CDCl3): δ= 1.79 (m, 4H); 2.04 (m, 4H); 2.32 (s, 6H); 7.13 (d, J = 8.6 Hz, 2H), 7.37 (d,
J = 8.6 Hz, 2H); 13C-NMR (CDCl3): δ 14.9, 21.1, 22.5, 25.7, 107.3, 109.2, 121.8, 125.6, 125.9, 126.0,
126.8, 130.2, 130.3, 150.4, 169.2; IR (KBr, cm-1): 3040, 2900, 2890, 1760, 1430, 1200, 690; MS
(FAB) m/z: 406 [M]+; Anal. Calc. for C19H18O2S4: C, 56.15; H, 4.43; S, 31.52. Found: C, 55.85; H,
4.31; S, 31.47.
2-(4-Acetoxyphenyl)-3-methyl-6,7-(buta-1,3-dien-1,4-diyl)tetrathiafulvalene (5d). Yield: 31 %; mp:
1
160-161 °C; H-NMR (CDCl3): δ 2.07 (s, 3H), 2.33 (s, 3H), 7.13 (m, 2H), 7.14 (d, J = 8.6 Hz, 2H).
13
7.27 (d, J = 8.6 Hz, 2H), 7.40 (m, 2H); C-NMR (CDCl3): δ 14.9, 21.1, 121.8, 121.9, 125.4, 125.8,
130.0, 130.2, 137.0, 137.1, 150.5, 169.2; IR (KBr, cm-1) 3010, 2900, 2890, 1730, 1500, 1200, 690; MS
(FAB) m/z: 402 [M]+; Anal. Calc. for C19H14O2S4: C, 56.71; H, 3.48; S, 31.84. Found: C, 56.40; H,
3.36; S, 32.34.
2-(4-hydroxyphenyl)-3-methyl-6,7-dialkyl tetrathiafulvalenes 6a-d
Hydrazine hydrate (3 mL) was added dropwise to a suspension of 5a-d (1.4 mmol) in methanol (30
mL) at room temperature. After the reaction mixture was stirred for 4 h, water was added. The
precipitate was collected by filtration and washed with water. The solid was collected and column
chromatographed on silica gel with dichlomethane as eluent to afford 6a-d.
p-Hydroxyphenyltrimethyltetrathiafulvalene (6a). Yield: 75 %; mp: 158 °C; 1H-NMR (CDCl3): δ 2.14
(s, 6H), 2.40 (s, 3H), 7.4 (m, 4H), 9.40 (s, 1H); IR (KBr, cm-1): 3640, 2919, 2850, 1503, 1433, 1168,
693; MS (FAB) m/z: 338 [M]+.
2-(4-Hydroxyphenyl)-3-methyl-6,7-(propane-1,3-diyl)tetrathiafulvalene (6b). Yield: 72 %; mp: 132
°C; 1H-NMR (CDCl3): δ 2.5 (m, 6H), 2.46 (s, 3H), 7.35 (m, 4H), 9.85 (s, 1H,); IR (KBr, cm-1): 3650,
2917, 2849, 1604, 1439, 1094, 701; MS (FAB) m/z: 350 [M]+.

Molecules 2006, 11
784
2-(4-Hydroxyphenyl)-3-methyl-6,7-(butane-1,4-diyl)tetrathiafulvalene (6c). Yield: 78 %; mp: 110 °C;
1H-NMR (CDCl3): δ 1.75 (s, 4H), 2.25 (s, 4H), 2.44 (m, 3H), 7.62 (m, 4H), 9.80 (s, 1H); IR (KBr,
cm-1): 3649, 3051, 2926, 1604, 1329, 1170, 747; MS (FAB) m/z: 364 [M]+.
2-(4-Hydroxyphenyl)-3-methyl-6,7-(buta-1,3-dien-1,4-diyl)tetrathiafulvalene (6d). Yield: 80 %; mp:
155 °C; 1H-NMR (CDCl3): δ 2.07 (s, 3H), 7.06 (m, 8H), 9.39 (s, 1H); IR (KBr, cm-1): 3417, 3037,
2903, 1358, 1123, 836, 693; MS (FAB) m/z: 360 [M]+.
Acknowledgements
We thank the Agence Nationale de Développement de la Recherche Universitaire (ANDRU)-
Algérie for financial support.
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Sample Availability: Samples of some of the compounds mentioned are available from the authors.
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