Background of the Author

In Indonesia, I studied chemistry, such as, Anlytical chemistry, organic chemistry, inorganic chemistry, and physical chemistry. In analytical chemistry, I was studied basic Analytical chemistry, separation, electrical analytical and spectrometry analytical methods, practical skill was include in this subject. I also was studied basic of organic chemistry, organic laboratory skill was include, too. And I also studied synthesis organic and physico, structure and identification organic compounds.

In inorganic chemistry subject, I was studied basic of inorganic chemistry subject. I studied basic of organic chemistry such as, nonmetal and metal and also I was studied about inorganic structure and reactivity, practical also include in this subject. About physical chemistry I studied about thermodynamic, kinetics, and dynamic, and also practical skill include in this subject. Beside that I was studied basic and advance biochemistry, also practical include in this subject. In the last year I studied about applied chemistry, such as, food biochemistry, industrial microbiology, analytical of life natural product and materials chemistry.

I interest to join with your laboratory, because I can research the applied chemistry, especially about material organic. The other reason is in my university there is organic research group which already extract lot of organic compound, such as, indonesianin, itebein, artoindonesian, etc. But so many organic chemistry which was not used by another researchers. So, If I can research and get skill in this field research, I can use those organic compounds for this compounds and this applicable.

Research Purpose

The aim of this research is Synthesis Superconductor Material Organic Dibenzotetraoxafulvalene salt (DB-TOF)2ClO4 Using of Electrocrystallization Method

Introduction

The first interest in organic superconductors was aroused in 1964 when W A Little proposed a model of a superconductor that could possibly superconduct at very high temperatures. Little's model comprised of a conducting chain with polarisable molecules attached to it. These polarisable molecules would have a similar effect on electron movement as atoms in a normal superconductor do, but because the effects are caused by the movement of electrons, not whole atoms, the effects would be noticed at much higher temperatures. Unfortunately, Little's model is a one dimensional system, and so any superconducting properties would be destroyed due to a Peierls transition, which would destroy the homogenousity of the material, and so cause the material to enter an insulating phase.

Most of the recent interest in organic superconductors has developed out of research into the properties of organic conductors. The first organic compound that was found to superconduct was (TMTSF)2PF6. The superconducting nature of this substance was discovered by K Bechgaard et al. in 1979 and since then a number of other salts of the form (TMTSF)2X have been found to have superconducting properties. Other organic compounds found to superconduct includes the family of salts (BEDT-TTF)2X. Recent research into buckminsterfullerene (C60) has found that fullerenes doped with alkali metals have superconducting properties. Although fullerenes are not generally considered to be organic molecules, the fullerene superconductors have a number of properties similar to those of the organic superconductors, primarily that the nature of the main conducting carriers is the same for the fullerenes and the other more typical Organic Superconductors, and so the fullerenes are generally considered in the same group as the organic superconductors. Nogami Takashi et al. was discovered the other molecule affording superconducting ion-radical salt. the molecule possessing oxygen atom in place of the chalcogen atoms. This molecule is Dibenzotetraoxafulvalene, the first derivative of tetraoxafulvalene. The following is the molecular structure of DB-TOF determined by an X-ray crystallography.

Electrocrystallization is an excellent technique to prepare high-quality conductive crystals. The process takes place by passing a current through a pair of platinum electrodes in an electrolyte solution containing electron donor molecules. Redox reactions occur near the electrode, and the radical cations generated are trapped by the anions from the electrolyte to form black and lustrous crystals on the anode. The procedure is a clean and self-purifying process. It is applicable to aqueous, organic, or molten salt solutions.

Methodology

Organic Superconductors, with the exception of the fullerenes, are crystals made up of a donor molecule, such as TMTSF or BEDT-TTF, and an anion. There are three main ways to make these crystals, electrocrystallization, direct reaction of donor molecule and anion, and precipitation by mixing solutions of the donor with another anion, and the anion with a different donor such that the desired crystal will form. The most practical method is electrocrystallization, which allows precise control of crystal growth and is generally quicker than the other methods. Electrocrystallization is carried out in a two chambered vessel, connected by a porous frit. The donor molecule is placed in one chamber and an electrolyte containing the desired anion is placed in the other. The chambers are then evacuated and filled with an inert gas. A solvent which has been distilled under an inert gas is then added, and the donor molecule and electrolyte are dissolved. Platinum electrodes are added and a constant current is passed through the system, with the anode being in the chamber with the donor molecule. The current used varies with the crystal being grown, and the amount of time for a crystal can grow ranges from a few seconds to 2-3 weeks, compared with a few months, and can be controlled somewhat by adjusting the current and temperature in which they are grown. Crystals of organic superconductors are usually only a few millimeters in each direction.

Relavant Research.

There are several different types of organic superconductors, with the major difference being the organic molecule on which each is based.

Bechgaard salts: Bechgaard salts are salts based on the molecule tetramethyltetraselenafulvalene (TMTSF). The salts are of the form (TMTSF)2X, where X is a singly charged anion. The first bechgaard salt found to superconduct was (TMTSF)2PF6, in 1979 by Bechgaard et al. A number of other salts based on the TMTSF molecule have been found to superconduct, including (TMTSF)2ClO4, which superconducts at ambient pressure.

The structure of the molecules within the salts is similar to that of several brick walls lying next to each other. Because of the distances between the molecules in this arrangement, the ability of the electrons in the system to move between molecules is different in each direction. The electrons are most free to travel up the columns of molecules, because of the significant amount of orbital overlap. Movement between parallel rows of molecules is much less than that up the columns, but is still significant. Motion along the rows of molecules is highly restricted, due to the presence of the anions. Because of these differences in conductivity, the Bechgaard salts show a quasi one-dimensional behavior. Superconductors have been created based on variants of the TMTSF molecule, such as tetramethyltetrathiofulvalene (TMTTF) in which the selenium atoms are replaced by sulfur atoms.

BEDT-TTF salts: These salts are based on the molecule bisethylenedithio-tetrathiofulvalene (BEDT-TTF). The salts are of the form (BEDT-TTF)2X, where X is a singly charged anion, like the Bechgaard salts. However, the BEDT-TTF salts differ from the bechgaard salts in a number of important ways. The arrangement of the molecules in the BEDT-TTF salts is planar, with a number of planes stacked on top of each other. The BEDT-TTF molecules form the planes, with the anions acting as filler between the planes. There are a number of different ways that the BEDT-TTF molecules can be arranged within the plane, each of which is designated by a Greek letter. Conductivity within the planes is much greater than that between planes, and the BEDT-TTF salts display two-dimensional behavior.

Fullerenes: Fullerene superconductors are crystals of fullerenes doped with alkali metals such as Potassium and Rubidium. Although not an organic compound, the fullerene superconductors have a number of properties similar to those of the organic superconductors, and are usually considered in the same group. The structure of a fullerene superconductor is a face centered cubic lattice, with fullerene molecules at the corners of the cube, and the alkali atoms in the center of each face. Because the directions in the fullerenes are symmetrical, the fullerene superconductors have none of the anisotropy observed in other organic superconductors. The image to the right shows a cell of a fullerene superconductor. The large yellow spheres represent molecules of buckminsterfullerene (C60). The smaller dark and light blue spheres represent an alkali metal.

Reference:

http://ttf.pc.uec.ac.jp/www.page/research/kenkyuushousai-E.html, take at February, 3th, 2003.

http://www.physics.uq.edu.au/people/brake/osc.html, take at February, 4th, 2003.

AtkinsPhysical Chemistry, McGraww Hill, London.