Tailoring interfacial chemistry

Figure 2. By tailoring the interfacial chemistry of the monolayer, it is possible to selectively sequester a variety of environmentally problematic metal species.

When chemical specificity is called for, a highly selective thin film is one solution. For analytes of major concern— Hg, trichloroethylene, Cr and certain organophosphonates— it may be worthwhile to use a complex, multistep procedure to synthesize a material that responds to a single analyte or narrow chemical class. In a few instances, very simple materials are quite selective for particular analytes examples include gold films to detect mercury (if sulfur compounds are not present to interfere) and palladium films for the detection of hydrogen (unsaturated hydrocarbons can interfere in this case). When such simple, obvious interfaces are unavailable or inadequate, scrutiny of the literature of interfacial chemistry, bulk-phase coordination chemistry, and catalysis (16) may point the way for the development of a tailored interface. But to utilize the one-analyte/one-(new)-film approach for general-purpose chemical detection systems, which could be called upon to recognize tens or hundreds of analytes in the presence of many interferants, is impractical, so alternatives must be examined. 

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