Dobby Ttf Electron Donor Synthesis And Physical Studies

Since the first organic metal TTF-TCNQ was discovered in 1973, great progress has been achieved in the field of organic conductors and superconductors. Efforts are still been devoted to improving the interesting conductive properties of the charge-transfer salts or cation-radical salts by increasing the dimensionality of these materials which can suppress the Peierls-Frohlich distortion at low temperature. One of the most interesting approaches employed for increasing dimensionality is enhancing the intermolecular interactions in the cation radical salts by means of chemical modification of TTF molecule, which is essential for the realization of highly conducting metallic and supercondcuting organic charge transfer salts. Here, we would like to report the synthesis and electrochemical properties of one TTF dimmer(1) and two novel TTF trimers(2a,b) as well as two TTF tetramers(3a,b). The studies of their cation-radical salts ( and charge-transfer salts ) and conductive LB films will also be described. Main parts of the research work are listed as follows:(1) New electron donors 1-3b containing two to four TTF nuclei were synthesized and characterized by 1H-NMR, MS and FT-IR.(2) The redox potentials of the new electron donors were measured with cyclic voltammetry and the comparison with ET(bisethylenedithiotetrathiafulvalene) in this respect was made. The results indicated that all of the new electron donors possessed similar electron-donating properties as ET.(3) Both new electron donors 2a and 3a can form stable mono-layer on the air-water interface. The corresponding multi-layer LB films were deposited on various substrates. The room temperature conductivity of the LB films after I2 doping are ranged in 10-7~10-5 S.cm-1. And the absorption spectra, before I2 doping and after I2 doping, were also investigated.Single crystals of four cation radical salts based on an ethylenedisulfanyl linked tetrathiafulvanlene (bis(ethylenedithiotetrathiafulvalenylsulfanyl) -enthane, 4) 4([TCNQF4]2, 4(PF6(CH2Cl2)0.5, 4(AsF6(CH2Cl2)0.5 and 4(BF4 were prepared by chemical oxidation and electrocrystallization. The crystal structures of these salts along with their electrical conducting behaviors are described,. For comparison, the crystal structure of the neutral donor is also reported. In the crysrtal of 4([TCNQF4]2 salt the donor molecules adopt a(4) Z-shape conformation with two TTF moieties loacting at the different side of the bridge, which is similar as what were observed in its neutral crystals. Charges on each TTF moieties are +1, and no continuous (-( overlaps exist in this crystal. This has lead to a insulator behavior of this salt with (rt<10-7Scm-1. The two salts with PF6 and AsF6 are isostructural, in which the donor molecules adopt a U-shape conformation with two TTF moieties loacting at the same side of the bridge. The donor molecules pack into a two-dimensional layer structure with the TTF moieties from different donor molecules forming a dimeric structure, which serve as the conducting path. The stack pattern in the crystal of 4(BF4 is similar as that of 4(PF6(CH2Cl2)0.5 and 4(AsF6(CH2Cl2)0.5. 4(PF6(CH2Cl2)0.5, 4(AsF6(CH2Cl2)0.5 and 4(BF4 display semi-conducting properties from room temperature down to 60 K.