Sol−Gel Hybrid Silica Thin Films Doped with 2-(5-Amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide as Optical Chemical Sensors

• Published in: Chemistry of materials 1996-06, Vol.8 (6), p.1202-1209
• Main Authors: Panusa, Alessia, Flamini, Alberto, Poli, Nicola
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-gas interface; Surface physical chemistry
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm9504706

The metal(II) coordinating anion 2-(5-amino-3,4-dicyano-2H-pyrrol-2-ylidene)-1,1,2-tricyanoethanide (C11N7H2 -, L‘, λmax = 549 nm, εmax = 35 000 M-1 cm-1) has been incorporated as dispersed monomer at a fairly high concentration (c ≈ 0.06 M) in a thin film (thickness < 1 μm) of a two-component (poly(methyl methacrylate)/SiO2) glass. L‘ in the film reacts specifically with Hg2+, as mercury(II) acetate, in water, forming the corresponding monochelated pyrrolizinato complex, >HgL (λmax = 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 color change to violet. These systems have been investigated for future adaptation as optical chemical sensors.