Thiacalix-monocrown ethers with terminal functional groups at the lower rim: Synthesis and structure

Abstract

170 Nowadays, one of the intensively developed areas in organic chemistry focuses on design, synthesis, and studying the properties of nanoscale molecular sys tems containing several structural blocks capable of fulfilling different functions, for example, receptor and sensor functions. Such molecules can serve the basis for design of “smart” materials in various areas of nanoengineering and materials science. The most effi cient strategy of obtaining such nanosystems involves combination of appropriate structural fragments. In particular, combination of a calixarene and crown ether moieties in one molecule led to the appearance of a new class of receptors, calix crown ethers 1a, which exhibit extremely high alkali metal ion bind ing selectivities [1–9]. Polyether bridged calix[4]arenes 1b [1, 2] exhibit a high Cs+/Na+ selectivity (more than 30 000) in solution. They are widely used as iono phores and carriers in liquid membranes [3, 4]. However, no attempts to fix them onto a solid sub strate for creating ion selective electrodes and sen sors have been described so far, since no efficient ways of synthesis have been developed for calix crown ethers in which the acyclic substituent R contains functional groups capable of fixing the molecule onto a solid surface and forming regularly arranged nanolayers and films. In this context, it is of definite interest to introduce thiol groups into such structures, since they can be efficiently fixed on the gold and silver surface [10]. CHEMISTRY