The sensing scheme the authors have designed for the detection of ethylene is based on a fluorescence turn-on mechanism and mimics nature by using a copper(I) complex to bind to ethylene. The fluorescence of the conjugated polymer is partially quenched by the presence of copper(I) moieties that can coordinate to the polymer. Upon exposure to ethylene gas, the copper complexes bind to the ethylene mols. and no longer quench the polymer fluorescence. The advantage of this fluorescence turn-on over a turn-off mechanism is that it requires a specific binding event to the copper to create a new signal, whereas fluorescence quenching can occur in multiple ways. Furthermore, if a completely dark background (completely quenched) state can be achieved, even a weak turn-on signal can be readily measured and thereby can allow trace detection. [on SciFinder(R)]