CONICET | Buscador de Institutos y Recursos Humanos

Two new fluorescent segmented conjugated polymers with either 1,4- or2,6-distyrylnaphthalene chromophores and their model compounds were synthesizedand the chemosensing abilities of the polymeric thin films to detect nitroaromatics (NACs) in aqueous media wereevaluated. The structural, thermal and optical properties of the polymers werecorrelated with those displayed by their corresponding model compounds. Changesin the connectivity of naphthylene units caused minor differences in opticalproperties, morphology and quenching efficiencies. Molecular modelinghighlighted the extremely bent character of polymermicrostructures that explains their high solubility and amorphous character. Polymericfilms are amorphous, strongly fluorescent and showed remarkable quenchingefficiencies in the nanomolar range with picric acid (PA) and trinitrotoluene (TNT).Quenching experiments using either different nitroaromatic quenchers,excitation wavelengths, excitation beam path-lengths, or time of exposure ofthe film to the quenching solution evidenced the dominant role of inner filtereffects (IFE) in the polymer response to NACs in the micromolar range. Thesensing response towards PA, a quencher that strongly absorbs at the excitationwavelength, has an IFE contribution even at the nanomolar range, while theresponse towards the non-absorbing TNT depends only on the quenching occurring afterdiffusion of the analyte into the film.