SOL-GEL HYBRID SILICA THIN-FILMS DOPED WITH ICYANO-2H-PYRROL-2-YLIDENE)-1,1,2-TRICYANOETHANIDE AS OPTICAL CHEMICAL SENSORS

The metal(II) coordinating anion icyano-2H-pyrrol-2-ylidene)-1,1,2-tri cyanoethanide (C11N7H2-, L', lambda(max) = 549 nm, epsilon(max) = 35 0 00 M(-1) cm(-1)) has been incorporated as dispersed monomer at a fairl y high concentration (c approximate to 0.06 NI) in a thin film (thickn ess < 1 mu m) of a two-component (poly(methyl methacrylate)/SiO2) glas s. L' in the film reacts specifically with Hg2+, as mercury(II) acetat e, in water, forming the corresponding monochelated pyrrolizinato comp lex, > HgL (lambda(max) = 670 nm). A color change from violet to blue occurs along with this transformation. The > HgL-doped film releases L ' in the matrix after interaction with small molecules, such as CN- in water or NH3 in the gas phase, generating the associated reversal col or change to violet. These systems have been investigated for future a daptation as optical chemical sensors.