XII Iberian Meeting of Electrochemistry XVI Meeting of the ...

XII Iberian Meeting of Electrochemistry & XVI Meeting of the Portuguese Electrochemical Society PE 15
Electrocrystallization of (D T-T T F) 2 [M(mnt) 2 ] on
microelectrodes
Rafaela A. L. Silva, 1 Mónica Afonso, 1 Manuel Matos 2,3 , Dulce Belo, 1
Manuel Almeida 1
1 Dept. Chemistry, ITN / CFMCUL Estrada Nacional 10, P-2686-953 Sacavém, Portugal
2
IT, Av. Rovisco Pais, P-1049-001 Lisboa, Portugal,
3 ISEL, Av. Emídio Navarro, P-1959-007 Lisboa, Portugal
rafaela@itn.pt
The charge transfer salts based on the organic donor dithiotetrathiafulvalene (DT-TTF)
and transition metal bis-maleonitrile-dithiolate M(mnt) 2 with M =Au, Ni, Cu, Pt and Pd,
are members of a general family of compounds with formula (DT-TTF) 2 [M(mnt) 2 ]
presenting strongly paired stacks of partially oxidized donor molecules (DT-TTF) + 2 [1].
The compounds of this family with diamagnetic anions (M=Cu, Au) have attracted
special interest because they were the first examples of organic spin ladder systems
[2,3].
The study of these materials requires both high quality large single crystals and
techniques able to characterize the electronic properties in rather small samples.
Crystals of these compounds can be obtained by electrocrystallization conditions typical
for charge transfer salts; the DT-TTF donor in a organic solvent is electrochemically
oxidized in the presence of [M(mnt) 2 ] - anions to form the compound as crystals
growing on the anode.
In order to obtain large single crystals of high quality we have performed a study aimed
at to optimize the electrocrystallization conditions. Using dichloromethane solutions and
Pt as electrodes we were able to obtain good single crystals as large as 5x1x0.1 mm 3 .
In order to make possible the measurement of electrical transport properties in smaller
crystals of these compounds it was developed a technique of electrocrystallization on
micropatterned electrodes. This technique using pulsed currents was able to provide
small crystals directly connected to microelectrodes which can be used directly to
electrical measurements.
Acknowledgments: Work supported by F CT under contract PTDC/QUI-QUI/101788/2008.
References
[1] Ribera, E.; Rovira, C.; Veciana, J.; Tarrés, J.; Canadell, E.; Rousseau, R.; Molins, E.; Mas, M.;
Schoefel, J-P.; Pouget, J.-P.; Morgado, J.; Henriques, R. T.; Almeida, M.; Chemistry an
European Journal, 1999, 5, (7) 2025-2039.
[2] Rovira, C.; Veciana, J.; Ribera, E.; Tarrés, J.; Canadell, E.; Rousseau, R.; Mas, M.; Molins, E.;
Almeida, M.; Henriques, R. T.; Morgado, J.; Schoefel, J-P.; Pouget, J.-P.; Angewandte Chemie,
International Edition in English, 1997, 36, 2324-2326.
[3] Ribas, X.; Mas-Torrent, M.; Pérez-Benítez, A.; Dias, J. C.; Alves, H.; Lopes, E. B.; Henriques, R.
T.; Molins, E.; Santos, I. C.; Wurst, K.; Foury-Leylekian, P.; Almeida, M.; Veciana, J.; Rovira,
C.; Organic spin-Advanced Functional Materials, 2005, 15, 1023-
1035.
September, 811, 2010. ISEL - Lisbon 106