dendrimers.5 Furthermore, important derivatives of cyanuric
chloride such as cyanuric or isocyanuric acids and melamines
acting as both hydrogen bond donors and acceptors are
important types of supramolecular building blocks able to
form stable aggreagates.6
as chemical sensors and redox-switchable ligands, molecular
shuttles, molecular switches and molecular rectifiers.17
Furthermore, it has also been confirmed that TTF can display
efficient nonlinear optic (NLO) responses in the second and
third harmonic generation,18 and as materials for photovoltaic
applications.19
In addition to the interest of s-triazines as biologically
active compounds,2,3,7 1,3,5-triazines have also found im-
portant applications in materials science. Thus, mesoporous
metal-organic frameworks have recently been prepared as
truncated-octahedral crystals by solvothermal reaction be-
tween triazine-1,3,5-tribenzoic acid and Tb(NO3)3.5H2O
forming pores of around 5 nm in diameter.8 Furthermore,
triazine-based materials for electroluminescence devices,9
donor-acceptor redox-active materials,10 nonlinear optics,11
two-photon absorption materials,12 magnetic properties,13 as
well as concave-convex supramolecular interactions between
electroactive highly phenylated triamino-s-triazines and
[60]fullerene14 are some remarkable examples which have
been reported along the last recent years.
Very recently, the synthesis and structural study of mono-
and bis(tetrathiafulvalene)-1,3,5-triazines as covalently linked
donor-acceptor systems has been reported.15 Again, the
synthesis of these compounds was carried out from cyanuric
chloride as starting material and the resulting compounds
showed a planar geometry with strong electronic interaction
between the electroactive donor and acceptor moieties.
Interestingly, these compounds were obtained in remarkably
low yields (3%) for those compounds bearing one or two
tetrathiafulvalene (TTF) units covalently linked to the
s-triazine ring. Furthermore, no data were given for the
preparation of the C3 symmetric compound endowed with
three TTF units.
In our group we have previously reported different TTF-
containing molecules built on the 1,3,5-benzene core with a
C3 symmetry.20 In this communication we report on the
preparation of a new and readily available C3 symmetry
building block (3) endowed with three phosphonate groups,
which easily undergoes further olefination reactions to afford
in a straightforward manner s-triazine derivatives. Since
aldehydes and ketones are widely spread in the toolbox of
organic chemistry, this approach represents a highly versatile
procedure for the synthesis of conjugated s-triazine deriva-
tives. The preparation of the intermediate building block was
carried out in two steps from readily available materials as
it is shown in Scheme 1. Thus, reaction of p-bromometh-
ylbenzonitrile (1) with triflic anhydride in refluxing dichlo-
romethane led to the new s-triazine 2 in 93% yield by
following a similar procedure to that reported in the literature
for related compounds.21 Further Arbuzov reaction by
refluxing 2 with trimethyl phosphite afforded the new
building block 3 bearing three phosphonate groups in 80%
yield. Compounds 2 and 3 were fully characterized by using
spectroscopic techniques (UV-vis, FT-IR, 1H and 13C NMR,
HR-MS). Thus, in addition to the aromatic protons, com-
pound 2 showed a singlet at 4.58 ppm for the methylene
groups whereas in 3, these methylene protons appear as a
doublet (3.31 ppm, J ) 22 Hz) due to the coupling with the
P atom of the phosphonate group. The methoxy groups of
the phosphonate, again coupled with the phosphorus, appear
as a doublet at 3.72 (J ) 11 Hz). HR-MS confirmed the
proposed structures, showing as the main fragmentation the
retro-cyclotrimerization process which leads to the corre-
sponding nitrile derivative (see Supporting Information).
Compound 3 is a very appealing building block for the
construction of more complex s-triazine derivatives by
Wittig-Horner olefination reactions with a variety of alde-
hydes. Thus, as a proof of the chemical reactivity of 3, we
have carried out the synthesis of two new 1,3,5-triazine
derivatives by reaction with formylferrocene (4) and formyl-
TTF (6).22 The reactions were conducted under the same
experimental conditions, n-butyllithium under argon atmo-
TTF and its derivatives are well-known strong electron
donor molecules which have been used extensively in the
preparation of salts and charge transfer complexes exhibiting
electrically conducting properties.16 More recently, TTFs
have found application in many other scientific areas such
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