Synthesis and monolayer study of a new amphiphilic photochromic crown-ether

The ionoselective and photosensitive properties of the new amphiphilic crow n-ether dye {perchlorate of 2-[(E)-2-(2,3,5,6,8,9,11,12-octahydro- 1,4,7,10 ,13-benzopentaoxacyclopentadecin-15-yl)]-5-octadecanoylamino-3-ethyl-1,3-be nzothiazolium} in monolayers have been studied. The collapse pressure of th e dye monolayers is about 53 mN/m on distilled water, slightly increases up to 57-59 mN/m in the presence of Na+, Ca2+, Mg2+ cations and significantly decreases up to 43-44 mN/m in the presence of K+ cations in the aqueous su bphases. The area per dye molecule in monolayer is the smallest on water an d increases with increasing of the salt concentration in the aqueous subpha se. These are evidences for the existence of the dye-cation complexes in mo nolayers. The reversible changes of the reflection intensity (irans-cis-tra ns isomerization) by dye photoactivation can be observed only for the dye-c ation complexes at very low surface pressure in the liquid-expanded state o f monolayers. The changes of the reflection intensity by photoactivation in the Liquid-condensed state of the dye monolayers on KCl solution are found irreversible that may be due to the photodimerization of the dye to cyclob utane. (C) 1999 Elsevier Science S.A. All rights reserved.