The influence of native and methylated β-cyclodextrin on the electroreduction of nitrophenyl glycosides

• Cyclodextrins (CDs) affect electroreduction of nitrophenyl glycosides (R–NO2).
• Reduction of R–NO2 proceeds as one process in the presence of native β-CD.
• Reduction of R–NO2 is separated in the presence of methylated β-CD.
• Methylated β-CD stabilizes nitro radicals, whereas native β-CD destabilizes them.

The effect of native and methylated β-cyclodextrin on electrochemical processes of a series of nitrophenyl glycosides (o-, m-, and p-nitrophenyl β-d-galactopyranosides, as well as p-nitrophenyl α-d-galacto-, α-d-gluco-, α-d-manno-, α-l-fuco-, and β-l-fucopyranosides) in alkaline aqueous solutions on the mercury electrode was evaluated. The totally different influence of native and methylated β-cyclodextrin on electroreduction of nitrophenyl glycosides was discovered. According to electrochemical measurements (cyclic voltammetry and chronocoulometry) as well as theoretical method (molecular modelling) inclusion complexes are formed between both cyclodextrins and nitrophenyl glycosides. Although the inclusion processes took place for both cyclodextrins, the source of their different influence on the electrode processes is connected with their different abilities of nitro radical anion (de)stabilisation.

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