Amphiphile compound sensor

Aqueous molecular assemblies such as micelles and bilayer membranes are formed by the self-assembly of amphiphihc compounds (Figure 11.la, b) [10]. Aqueous micelles have been utihzed for a variety of apphcations in surfactant industry, including emulsification, washing, and extraction processes [11]. BUayer membranes are basic structural components of biomembranes, and their structures are maintained even in dilute aqueous media. This is in contrast to micelles that show dynamic equihbrium between aggregates and monomeric species. Thus bilayers are more stable and sophisticated self-assemblies, and they require suitable molecular design of the constituent amphiphiles. BUayer membranes and vesicles have wide-ranging applications, as exemphfied by drug dehvery [12], sensors [13], and bilayer-templated material synthesis [14]. 

Stabilization of a lipid membrane onto a solid support by covalent attachment also provides the physical stability necessary for the development of practical sensors. An oriented membrane can be prepared by allowing self-assembly of individual amphiphilic molecules onto a solid surface through either the reaction of terminal silane moieties with a hydroxylated surface to form a silyl ether [33,34], or by the reaction of sulfur-terminated compounds (alkylthiols or disulfides) with gold surfaces [35,36]. A variety of species, both with and without polar head groups, have been deposited onto surfaces such as glass, quartz, silicon, and gold [37-39]. These include phospholipids, fatty acids, and fatty amines which were synthetically altered so as to contain either a silyl chloride or a thiol moiety at the terminus of the acyl chain [40]. Both monolayers... 

Reaction of 3.40, 3.41, 3.43 or 3.51 with 1-methylimidazole, pyridine, amine " and tributylphosphine afforded cationic pillar[5]- and pil-lar[6]arenes (3.52-3.56). A pillar[5]arene with 10 ionic liquids (imidazolium cations 3.53) was produced in the liquid state at 25 °C by choosing an appropriate counter anion. A pillar[5]arene with 10 phosphonium cations (3.56) is amphiphilic and acts as a substrate-selective phase-transfer catalyst. Oxidation of linear alkane 1-hexene to 1-pentanal by KMn04 vwis >99%, whereas that of the branched alkene, 4-methyl-l-hexene, was only 31%, even under ideal conditions. An etherification reaction between an allqrl-halide and phenolic compounds is a good method to synthesize functionalized pillar[5]arene. Etherification of pillar[5]arene containing 10 bromide with a coumarin derivative with a phenolie moiety gave a pillar[5]arene eanying 10 coumarin moieties (3.57) 3.57 aeted as a fluorescence sensor for methyl parathion. Pillar[5]- and pillar[6]arenes with 10 and 12 bromide moieties should be good key compounds for the synthesis of various functionalized pillar[5]- and pillar[6]arenes. 

A great variety of organic and organometallic compounds, such as organic ligands and catalysts as well as organometallic catalysts, but also organic polymers and amphiphilic/lipophilic compounds, has been incorporated into carbon paste electrodes for sensor applications. They are briefly presented hereafter. 

---