MAGNETIC-FIELD EFFECT AND MULTIPLICITY OF CONFORMATION IN A POLYMER-LINKED EXCIPLEX SYSTEM

The magnetic field sensitivity of the pyrene-dimethylaniline (Py-DMA) system, linked by a polystyrene (PS) spacer, was examined. It was foun d that isodielectric mixtures of tetrahydrofuran (THF) and dimethylfor mamide (DMF) and benzene and dimethylsulphoxide (DMSO) behave differen tly, the latter quenching the magnetic field effect more than the form er; this is opposite to that found for the unlinked Py-DMA system. The se studies demonstrate the importance of the solvent-dependent polymer backbone conformation. It was found that, in both of the above solven t mixtures, the normal luminescence (phi) and the magnetic-field-modul ated luminescence (Delta phi) exhibit a shift in wavelength, indicatin g conformers with different magnetic sensitivities. The spectra taken at different times after excitation also support this conclusion.