Poly(N-vinylcaprolactam) gel/organic dye complexes as sensors for metal ions in aqueous salt solutions

The complex formation of organogels based on poly(N-vinylcaprolactam) (PVCa ) and organic dyes [5-(4-dimethylaminobenzylidene) rhodanine, alpha -nitros o-beta -naftol, and dithizone] and the properties of the complexes in salt aqueous solutions were studied. PVCa gels absorbed these dyes in organic me dia (ethanol and chloroform). Our main focus was the behavior of the gel/dy e complex immersed in a salt aqueous solution if the dye was the chelating ligand for metal ions. The behavior of the PVCa/dithizone (Dz)/chloroform s ystem was studied in AgNO3 aqueous solutions. The absorption spectra of gel /dye and gel/dye/metal ion systems were investigated. The results obtained indicate that Ag+ ions penetrate the gel phase and that the Dz/silver compl exes are indeed formed inside the gel. The dependence of the optical densit y of the gel/dye/metal ion systems on the AgNO3 concentration was observed. (C) 2001 John Wiley & Sons, Inc.