Fluorescent Amorphous Distyrylnaphthalene-Based Polymers: Synthesis, Characterization and Thin-Film Nanomolar Sensing of Nitroaromatics in Water

RAÚL O. GARAY; ANA B. SCHVVAL; MARCELA F. ALMASSIO; PABLO G. DEL ROSSO; MARIA J. ROMAGNOLI; ROSANA S. MONTANI

POLYMER

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2018

0032-3861

Two new fluorescent segmented conjugated polymers with either 1,4- or2,6-distyrylnaphthalene chromophores and their model compounds were synthesized and thechemosensing abilities of the polymeric thin films to detect nitroaromatics (NACs) in aqueous mediawere evaluated. The structural, thermal and optical properties of the polymers were correlatedwith those displayed by their corresponding model compounds. Changes in the connectivityof naphthylene units caused minor differences in optical properties, morphology and quenchingefficiencies. Molecular modeling highlighted the extremely bent character of polymer microstructuresthat explains their high solubility and amorphous character. Polymeric films are amorphous, stronglyfluorescent and showed remarkable quenching efficiencies in the nanomolar range with picricacid (PA) and trinitrotoluene (TNT). Quenching experiments using either different nitroaromaticquenchers, excitation wavelengths, excitation beam path-lengths, or time of exposure of the filmto the quenching solution evidenced the dominant role of inner filter effects (IFE) in the polymerresponse to NACs in the micromolar range. The sensing response towards PA, a quencher thatstrongly absorbs at the excitation wavelength, has an IFE contribution even at the nanomolar range,while the response towards the non-absorbing TNT depends only on the quenching occurring afterdiffusion of the analyte into the film.