Unusual 'Turn-on' Ratiometric Response of Fluorescent Porphyrin-Pyrene Dyads to the Nitroaromatic Compounds

Detection of nitroaromatic compounds (NAC) is an important task since these substances are hazardous to both the biosphere and the society. Fluorescent sensors developed for NAC detection usually demonstrate a 'turn-off' response to the analyte, while 'turn-on' sensors are rarely reported. Here, we present a showcase report on new pyrene-imidazoporphyrin dyads that demonstrate an unusual analytic response to NAC with clear 'turn-on' behavior followed by an unexpected appearance of a new band, which can be ascribed to exciplex emission. The porphyrin backbone of the dyad also allows registration of its own fluorescence, providing an internal reference signal for ratiometric detection. The association constants in the order of 10(4) M-1 are reported.

Automated summary

Detection of nitroaromatic compounds (NAC) is important due to their hazardous nature. A new pyrene-imidazoporphyrin dyad is reported to exhibit an unusual 'turn-on' response to NAC with the appearance of a new band attributed to exciplex emission. The dyad's porphyrin backbone allows for ratiometric detection using its own fluorescence as an internal reference signal. Association constants of the dyad are reported to be in the order of 10(4) M-1.