| Popis: |
The outer-sphere complex formation constants between adenosine 5′-triphosphate (ATP) and the pendant arm macrocycles trans -6,13-dimethyl-1,4,8,11-tetraazacyclotetradecane-6,13-diamine ( 1 ) and 10-(3′-aminobenzyl)-1,4,8,12-tetraazacyclopentadec-10-ylamine ( 2 ) as well as the linear polyamine pentaethylenehexamine ( 4 ) are reported. For a given polyamine, the strength of the interaction with the ATP 4− anion increases with increasing degree of protonation and conversely the complex stability decreases as the charge on the anion decreases, as anticipated. The kinetics of ATP hydrolysis alone and in the presence of 1,2,4 and tetraethylenepentamine ( 3 ) have been followed by a recently-established attenuated total reflectance infrared (ATR-IR) method, illustrated here with complex systems for the first time. Results obtained for spontaneous hydrolysis and catalysis by protonated 3 and 4 agree well with determinations employing other techniques, indicating the general applicability of the new method. The presence of pendant protonated amine groups on macrocycles do not enhance catalysis compared with unsubstitutes macrocycles. Catalytic effects from the protonated acyclic polyamines are larger than those induced by the macrocycles. The dexibility of the polyammonium compound plays an important role towards optimising interaction with ATP in the precursor outer-sphere complex. |
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