3-(3-indoyl)-propyl methacrylate (IPM) was prepared and subsequently c
opolymerized with methylmethacrylate (MMA) in order to obtain a poly-(
methyl methacrylate) containing fluorescent indolic groups (PMMI). 3-(
3-indoyl)-propyl isobutyrate (IPI), was also synthetized as a model co
mpound. Characterization of the polymer gave a molecular weight of 200
,000 and a mean average number of 2.5 indolic units per chain. The mod
el compound and the polymer showed the same absorption spectra, with a
maximum at 280 nm. The emission spectra for both compounds were stron
gly dependent on the solvent, with a shift of the emission wavelengths
towards the red in polar solvents. In a given solvent, both polymer a
nd model emit at the same wavelength, the only exception for this was
observed when 1-propanol was employed as solvent. This was attributed
to a ''chain effect'' exerted by the strongly folded macromolecule, sh
ifting the emission wavelength toward values corresponding to polariti
es lower than the bulk solution. In solvent mixtures, the maximum emis
sion wavelength shifts can be considered as indicative of the probe en
vironment, reflecting a sort of preferential adsorption of the compone
nt with the highest thermodynamic power onto the macromolecular chains
. Finally, a number of quenching experiments were performed in pure so
lvents and solvent mixtures, showing that the deactivation process is
diffusion-controlled. The lower values found for the polymer could ind
icate that the quencher finds a certain resistance to penetrate the po
lymer coil, which might be due to steric effects or a higher local vis
cosity within the macromolecular coil.