Design protocols in triarylamine cored dendrimer-based explosive sensors

Abstract

The preparation, photophysical characterisation and explosive sensing of two first-generation triarylamine-based dendrimers are reported. The dendrimers are constructed of a triphenylamine core, dendrons comprised of a phenyl branching unit with thiophene (Dendrimer 1) or bithiophene (Dendrimer 2) moieties, and dodecyl surface groups. By simply changing the number of thiophene units within the dendrons, it was found that the emissive chromophore could be switched from the centre (Dendrimer 1) to the dendrons (Dendrimer 2). Both Dendrimer 1 and 2 detected nitro-aromatic and -aliphatic analytes by fluorescence quenching, with the former showing a much greater response. In particular, Dendrimer 1 showed a particularly high affinity for the difficult-to-detect nitroaliphatic taggant 2,3-dinitro-2,3-dimethylbutane (DMNB). A combination of steady-state and time-resolved Stern–Volmer measurements revealed that the high affinity for DMNB was due to a combination of long luminescence lifetime and dominant static quenching.