, Volume 376, Issue 7, pp 1041-1052
Date: 05 Jul 2003

Determination of protonation constants of some fluorinated polyamines by means of 13C NMR data processed by the new computer program HypNMR2000. Protonation sequence in polyamines

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Abstract.

The pK a values of 6-fluoro-4,8-diazadodecane-1,12-diamine (6-fluorospermine) (1), 6,6-difluoro-4,8-diazadodecane-1,12-diamine (6,6-difluorospermine) (2), 6-fluoro-4-azaoctane-1,8-diamine (6-fluorospermidine) (3) and 6,6-difluoro-4-azaoctane-1,8-diamine (6,6-difluorospermidine) (4) in D2O solution have been determined at 40 °C from 13C NMR chemical shifts data using the new computer program HypNMR2000. The enthalpies of protonation of compounds 1–4 and the parent amines spermine (5) and spermidine (6) have been determined from microcalorimetric titration data. The values of ΔH° were used to derive basicity constants relative to 25 °C. The NMR data have been analysed by two different methods to obtain information on the protonation sequence in the polyamines 1–5. The protonation sequence for spermine is related to its biological activity.

Presented at the Spanish-Italian Congress on the Thermodynamics of Metal Complexes, Santiago de Compostela, Spain, June 2–6, 2002