RESUMO
Two copolymers, one containing a chiral center and another without any asymmetric site are studied regarding their chiro-optical properties. The pure polymers do not show any signal of chiro-optical activity, only a smooth line is observed in the circular dichroism spectra, even for the chiral material. However, blends containing the achiral one as a major component show striking chiro-optical activity, originating by stable supramolecular structures whose size and shape remain unchanged, regardless of the blend composition. Only the number of such structures (composed by the chiral one), vary with blend composition. The results suggest that working with supramolecular morphology can be an important strategy to attain chiro-optical active polymers.
Assuntos
Polímeros , Dicroísmo CircularRESUMO
4,5-Bis(phtalimidomethyl)acridine (L) was studied as a chemosensor for metal ions in alcoholic matrices and showed to be selective for Al3+, through a linear fluorescence enhancement of 230% in the concentration range of 10-70 µmol L-1. Benesi-Hildebrand and Job's formalisms indicated the formation of a 1:1 (Al3+:L) complex with a binding constant of 6.30 × 103 L mol-1. DFT/TDDFT calculations allowed access to the energies of frontier orbitals and could explain the fluorescence augmentation upon complex formation, due to the restraining of PET process. Limit of detection and limit of quantification (R2 = 0.998, least squares method) are 1.130 and 3.768 µmol L-1, respectively, and validation was verified based on the variation of several analytical conditions. Practical application in spiked Brazilian sugarcane spirit showed recovery of (84 ± 0.42)% with no effect of interfering ions.