UV-light-induced hydrogen transfer in guanosine-guanosine aggregates.

Aggregates of a lipophilic guanine (G) derivative have been studied in n-hexane by femtosecond-to-microsecond UV-visible broadband transient absorption, stationary infrared and UV-visible spectroscopy and by quantum chemical calculations. We report the first time-resolved spectroscopic detection of hydrogen transfer in GG aggregates, which leads to (G-H)(·) radicals by means of G(+)G(-) charge transfer followed by proton transfer. These radicals show a characteristic electronic spectrum in the range 300-550 nm.

Characterization of maleimide dimers in photo-cross-linked copolyimide films.

Copolyimide membranes are established materials for the separation of gaseous and liquid mixtures. Cross-linking of the polymer strands improves the physical and chemical stability. The photo-cross-linking of a 6FDA-ODA/6FDA-DABA 4 : 1 copolyimide membrane containing maleimide side groups as linker was investigated by FTIR spectroscopy.

Investigation of cross-linked and additive containing polymer materials for membranes with improved performance in pervaporation and gas separation.

Pervaporation and gas separation performances of polymer membranes can be improved by crosslinking or addition of metal-organic frameworks (MOFs). Crosslinked copolyimide membranes show higher plasticization resistance and no significant loss in selectivity compared to non-crosslinked membranes when exposed to mixtures of CO2/CH4 or toluene/cyclohexane. Covalently crosslinked membranes reveal better separation performances than ionically crosslinked systems.