Diphenylanthrylene and diphenylfluorene-based segmentedconjugated polymer films as fluorescent chemosensors for nitroaromatics in aqueous solutionsolution

PABLO G. DEL ROSSO; MARÍA J. ROMAGNOLI; MARCELA F. ALMASSIO; CESAR BARBERO; RAÚL O. GARAY

SENSORS AND ACTUATORS B-CHEMICAL

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2014 vol. 203 p. 612 - 620

0925-4005

A new regularly segmented conjugated polymer with diphenylanthryl chromophores bearing oxyethy-lene side chains was synthesized. The amorphous polymer was solution-processable. The formation ofaggregated species in solid phase was hindered by the bent microstructure while fluorescence depolar-ization measurements showed high exciton mobilities among the short chromophores. The fluorescencequenching of films of PA toward nitroaromatics in aqueous solution was evaluated and compared withthe behavior of PF; a diphenylfluorenylene-based segmented CP bearing non-polar aliphatic side chains.Films of both polymers exhibit remarkable sensing abilities in the micromolar range thus showingthat hydrated films have porosity at the molecular level. The fluorene-based PF had higher overallquenching responses to NACs than the anthryl-based PA while nitrophenols were more effective thannitrotoluenes in quenching the fluorescence of both PA and PF. Such differences are rationalized in termsof polymer?analyte interactions. The binding strengths between analytes and sensing materials wereevaluated by their Hansen solubility parameters. We concluded that strong analyte cohesive interactionswith the polymer could drag analyte diffusion and impair polymer sensing ability and should be avoidedin the design of responsive polymers to be used in the present sensing configuration.