COMPLEXATION OF TRANSITION-METAL IONS, SN-II, PB-II AND AL-III WITH NUCLEOBASE-SUBSTITUTED POLYETHERS AND DISSOCIATION OF ADDUCT IONS STUDIED BY FAST ATOM BOMBARDMENT-MASS SPECTROMETRY

Metal-ion-complexed dinucleotide analogues were studied by FAB mass sp ectrometry using tri- and bi-valent transition-metal ions (Cr to Zn), Sn-II, Pb-II and Al-III. Pairs of thymine nucleobases linked by (CH2)( 2)[O(CH2)(2)]O-n(CH2)(2) chains (n = 11, 22, 33 or 44) and of adenine nucleobases (n = 15 or 46) co-ordinate tb metal ions and form; signifi cant [M + M - H](+) and [M + MCl](+) ions. In addition, many transitio n-metal ions also give : [M + M(2)X - 2H](+) (X = Cl Or NO3) ions but Cr-III produces [M + CrCl2](+) ions. The effect of the spacer chain le ngth is reflected in the ease of formation of [M + M - H](+) and [M MX](+) ions. Fragmentation of [M + MX](+) and [M + M(2)X - 2H](+) ions give [M + M - H](+) ions, suggesting that metal chelation through the nucleobase is more favoured than through the polyether. Complexes of compounds 1-6 with Al-III-glycerol give abundant [M + 117](+) complex ions (117 = Al + glycerol - 2H). The intensities of these ions decreas e with increasing number of ethylene oxide units from 1-4. The same tr end is also observed in 5 and 6. Bimetallic ions with an unipositive c harge are also produced from 1-4. Dissociation of adduct ions labelled with deuterium confirms the substitution of amide protons with alumin ium(III) in the elimination of glycerol.