Conjugated polymers for the fluorescent detection of nitroaromatics: Influence of side-chain sterics and [pi]-system electronics

A series of eight poly(p-phenylene vinylene) (PPV) and poly(p-phenylene ethynylene) (PPE) (P1-P8) derivatives were tested for their ability to detect the nitroaromatic explosive 2,4,6-trinitrotoluene (TNT) and its model compound 2,6-dinitrotoluene (DNT). The polymers P1-P8 represent five structural classes that have not been examined for nitroaromatic sensing. These new motifs include PPE derivatives with a main-chain m-terphenyl unit (P1) or oxacyclophane canopy-like structure (P2) and PPV derivatives with 2,6-mesitylenephenylene repeats (P3 and P4), 9,9-dialkyl-1,4-fluorenylene repeats (P5 and P6), or m-phenylene units that periodically disrupt π-conjugation along the backbone of the polymer (P7 and P8). The time-dependent photoluminescent response of films to TNT and DNT and the solution-phase Stern-Volmer quenching constants for both TNT and DNT were determined. The results are rationalized in terms of side-chain sterics and π-system electronics and are discussed relative to known conjugated polymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 1487-1492 [PUBLICATION ABSTRACT]