V . d e Z e a B e r m u d e z S e c ção d e Q uím i c a , U n i ve r s i d a d e d e T r ás -o s -M o n t e s e A l t o D o u r o , A p a r t a d o 2 0 2 , Q u i n t a d e P r a d o s , 5 0 0 1 V i l a R e a l C o d e x , P o r t u g a l L . D . C a r l o s D e p a r t a m e n t o d e Fís i c a , U n iv e r s i d a d e d e Av e i r o , 3 8 0 0 Av e i r o , P o r t u g a l M . M . S i l v a and M . J . S m i t h D e p a r t a m e n t o d e Q uím i c a , U n iv e r s i d a d e d o M i n h o , 4 7

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... 1 9 B r a g a , P o r t u g a l A b s t r a c t Electrolytes formed with poly(oxyethylene), POE, and europium picrate [Eu(pic) 2 (OH 2 ) 6 ]pic.6H 2 O (where pic denotes the picrate anion) or simply Eu(pic) 3 xH 2 O, have been represented by POEnEu(pic) 3 xH 2 O (where n represents the molar ratio of (OCH 2 CH 2 ) units per Eu 3+ ion). Materials with n ranging from 133 to 11 have been examined. A tentative attribution of the absorption bands of the mid-infrared spectra is presented. The spectral changes detected in the mid-infrared region and the modifications in the XRD patterns at increasing salt content show that PEO n Eu(pic) 3 xH 2 O exerts an effective plasticizing role which leads to the complete supression of crystallinity at n = 11. The emission spectra of the complexes and their signature in the vC-O spectral region provide conclusive evidence that the Eu 3+ ions are coordinated to the oxygen atoms of the polyether chains over the whole range of compositions studied. The photoluminescence spectra of the PEO n Eu(pic) 3 xH 2 O electrolytes indicate that the Eu 3+ /ether oxygen complexation occurs with concomittant partial substitution of the water molecules from the cation coordination shell. The luminescence data obtained confirm that the latter aspect is quite advantageous from the standpoint of optical properties.