Researchers at the University of Massachusetts Amherst have created complex molecules containing zinc for use in portable sensors that detect the presence of plastic explosives. Sensors containing the zinc complexes are the first devices that allow the user to identify which type of explosive is present, since each metal complex has a unique response to explosives and explosive mimics.

"This is a big improvement over existing sensors based on polymers, since the metal complexes can discriminate between closely related explosives compounds," says Michael Knapp, a professor of chemistry. The zinc complexes are naturally fluorescent, but they lose this ability when exposed to chemicals contained in plastic explosives - a phenomenon called quenching.

Since each of the complexes react by losing different amounts of their fluorescent ability, they can be used to create sensor arrays that produce a different visual display when exposed to different explosives. During testing, the sensors also responded quickly, since the zinc complexes are very efficient at changing energy states, making them suitable for hostile environments.

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