Chemistry Reference
In-Depth Information
Figure 3.2. (a) Single crystals and (b) wires of EDT-TTF-(CONHMe)
2
observed
with an optical microscope. The substrate is highly doped silicon with a 500 nm
thermally grown oxide on top and titanium-gold contacts. Reprinted from
Synthetic
Metals
, Vol. 146, C. Colin, C. R. Pasquier, P. Auban-Senzier, F. Restagno, S. Bau-
dron, P. Batail and J. Fraxedas,
Transport properties of monocrystalline microwires
of EDT-TTF(CONHMe)
2
and (TMTSF)
2
ClO
4
, 273-277, Copyright (2004), with
permission from Elsevier.
However, when the evaporation of the solvent occurs very fast (few minutes)
then the resulting surface of the grown microcrystals is usually quite imperfect and
sometimes really rough and peculiar, as for the case of the EDT-TTF-(CONHMe)
2
microcrystals discussed a few lines above. Figure 3.3 shows nanovolcanoes orig-
inating at the surface due to the eruption of the solvent. The amazing nanoworld
that keeps captivating us!
Some binary MOMs form very stable phases in solution, which translates into
rapid synthetic processes. TTF-TCNQ belongs to this class of materials and can
be prepared quite simply as a black powder. In fact when highly purified TTF and
TCNQ are combined in CH
3
CN, the 1:1 complex precipitates from the solution.
A second example is the synthesis of the TTF[M(dmit)
2
]
x
compounds, where
M
Ni, Pd or Pt. Metathesis reaction under inert atmosphere of CH
3
CN solutions
of (TTF)
3
(BF
4
)
2
and the appropriate metal salt TBA[M(dmit)
2
] immediately yields
insoluble, black, shiny microcrystalline powders. Because TTF[M(dmit)
2
]
x
is vir-
tually insoluble in common solvents, its recrystallization from solution is precluded.
Therefore, when single crystals are needed some alternative synthesis routes have
to be undertaken.
In the case of TTF-TCNQ, single crystals with typical dimensions of 2
=
×
.
×
0
2
02 mm
3
can be grown from solutions of multiply distilled CH
3
CN using a
U-tube diffusion technique in a glove box filled with argon. High quality crys-
tals are usually obtained after approximately 3 days.
0
.
