Application Of Self-Assembled Monolayers Of Porphyrin In Electroanalytical Chemistry

An organized monolayer is a kind of single molecular layer which deposited in the surface of the electrodes. The specific property of the monolayer is that the molecules in the monolayer have a common direction, that is, the molecules are well organized and oriented. The molecules are aligned in the surface of the electrode. Their head and tail groups can be clearly identified. There are two common methods that we could employ to obtain the monolayer. One is the Langmuir-Blodgett method and often called LB method for simplicity; the other is self-assembly method. Self-assembly method is more popular and common than the LB method recently. The monolayer will form immediately on the substrate when it was exposed to a solution or a vapor containing the molecules. Thus, it requires that there should be a strong interaction between the molecules and the substrate and a lateral interaction between the molecules themselves when they are presented on the substrate(metal electrodes). These strong interactions will prevent the monolayer from being removed from the substrate. SAMs are not as popular as the LB monolayers because of the restrict requirements before the 1980's. After that time, SAMs become popular method with the discovery of the well-organized, stable monolayers formed by long-chain thiols on gold electrodes. From then on, SAMs have become a great interest among the analysts and many scientific papers are concentrated on this field.SAMs can be formed on many common electrodes, such as gold, silver, platinum, and mercury except carbon. The molecules contained in the SAMs are mostly sulfur compounds having alkane chains of different lengths, especially thiols, disulfides, and sulfides. And the most important is that these sulfur compounds contribute to the advantages of the SAMs. Since the sulfur compounds have strong affinity for the gold and other metal electrodes, the monolayer will deposit on the electrode within seconds to minutes. And the formation of monolayer has no special requirement for the solvents. Even the feature of the metal surface is not a strong point here because of the strong affinity of the sulfur for the metal. The size of the metal electrodes can range from macroscopic to submicroscopic. And their surfaces could be smooth or porous.Many scientists concentrated on the utilization of SAMs in the field of electrochemistry, especially employing those metal electrodes coated with thiol group and other relative sulfur compounds. The reason may ascribe to the specific properties of the sulfur atom. It can survive through the process of oxidation, reduction and desorption when undergoing the electrochemical experiments. Besides, the SAMs remain stable over a wide range of potential and allow the electrode to be coated with a variety of molecules bearing different functional groups and structures. SAMs have many potential applications in technology. Some applications are in the field of wetting, lubrication, adhesion, corrosion, biocompatibility, catalysis, chemical sensor, and nanoscale lithography etc. The most important and special applications of SAMs are the development of electrochemical sensors. The purpose of this effort is to explore more selective and sensitive sensors, especially the biosensors.This paper is aimed at the temporarily frontier study area of electrochemistry ?self-assembled monolayer, chemical sensor and electrocatalytic of metalloporphyrin. On the basis of careful study of most recent investigations and analysis of the development trends of the above area, we have designed and synthesized thiol-derivatized porphyrin and metalloporphyrin. Some meaningful conclusions have been drown on the basis of experimental results and theoretical analysis. All of these researchs and relevant results are reported in the followings:Chapter I Application of self-assembled monolayers of porphyrin in electroanalytical chemistryIn a bioreaction, porphyrin pigments play an important role in energy transfer, electro-transfer reaction and electro-transfer of photosynthesi...