TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The transition metal ion is silver(I), copper(I), cobalt(II), iron(II) or zinc(II). The transition metal salt is salts of silver (Ag+), copper (Cu+), cobalt (Co2+), iron (Fe2+) and Zinc (Zn2+), in which the anion is acetate, trifluoromethanesulfonate, tetrafluoroborate, hexafluorophosphate, nitrate, or perchlorate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The organic solvent is tetrahydrofuran, chloroform, and/or dichloromethane. The subunit T is present at 30-38 (preferably 34) mol.% compared to the number of moles of G subunits present in the copolymer.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The membrane has a thickness of 300-600 mu m. The membrane comprises a polymer having repeating units (a), preferably substituted phenol unit of formula (a1) or pyridine unit of formula (a2), which forms a complex with at least one transition metal ion. Preferred Process: The reaction mixture prepared in step (a1) further contains at least one salt of transition metal. Preferred Definitions:    R1 = methyl, ethyl, n-propyl, n-butyl or tert-butyl (preferred) in para position with respect to Y1; and    R3-R5 = CH3.    EXAMPLE - Isophthalaldehyde (0.3 g), poly(tetrahydrofuran) bis(3-aminopropyl) unit of formula (H2N-(CH2)3-(-O-(CH2)3-)x-O-CH2-CH2-CH2-NH2) (1.624 g) and glycerol tris(poly(propylene glycol)) ether having amino terminal unit (H2N-(CH(CH3)-CH2-O)17-CH(CH2-(-O-CH2-CHCH3-)17-NH2)2) were dissolved in tetrahydrofuran (80 ml). After overnight under magnetic stirring at reflux, the reaction mixture was evaporated to half its original volume (40 ml). The reaction mixture (6.7 ml) was poured into a molded Teflon (RTM: Polytetrafluoroethylene) deposited on a plate upgrade. Then the device was covered with a filter paper to slow evaporation and thus limits the creation of air bubbles. After 4 to 5 days, when solvent evaporation was complete, the films were placed in a vacuum oven at 70 degrees C for two additional days of drying to obtain self-supported polymer membrane.