Showing papers by "Southwest University published in 1989"
TL;DR: In this paper, the authors showed that the rate of 2,4-dinitrophenylphosphate (DNPP) hydrolysis can be accelerated in the presence of excess tn 2 Co(H 2 O) 2 3+ or trpnCo( H 2 O ) 2 3 + at rates which maximize at pHs close to those at which the hydroxoaquatetraaminecobalt(III) complex concentrations peak.
Abstract: The hydrolysis of 2,4-dinitrophenylphosphate (DNPP) to orthophosphate and 2,4-dinitrophenolate (DNP) is accelerated in the presence of excess tn 2 Co(H 2 O) 2 3+ or trpnCo(H 2 O) 2 3+ at rates which maximize at pHs close to those at which the hydroxoaquatetraaminecobalt(III) complex concentrations peak (tn 2 , pH ∼6.4; trpn, pH ∼6.0; tn = trimethylenediamine; trpn = 3,3′,3″-triaminotripropylamine). For dilute DNPP solutions (∼10 −4 M) the hydrolysis rates (25°C, 0.50 M NaClO 4 ) increase with increasing Co/DNPP ratio in ways that are qualitatively as well as quantitatively different for the two systems (trpn: steady increase moving toward rate saturation, higher rates; tn 2 : ‘S’-shaped curve with very low rates at low ratios, lower rates compared to trpn for comparable ratios). For the trpn system the results are interpreted on the basis of pre-equilibrium formation of the 1:1 monodentate-DNPP cobalt complex by substitution of the labile water on cobalt, and rate-determining attack by the cis -coordinated hydroxide on the phosphorus center to affect hydrolysis. For the tn 2 system the main path to hydrolysis is through a 2:1 cobalt to DNPP complex in which attack by a cis -coordinated hydroxide is again involved. The more complex rate behavior and the slower hydrolysis rates observed for tn 2 system result from the formation of cis and trans isomers in which trans arrangements of coordinated DNPP and hydroxide leave the latter unavailable to participate in intramolecular hydrolysis. Computer fitting of the observed rate data provides values of equilibrium and rate constants for the two systems. Detailed mechanistic schemes are proposed. For the trpn system at pH 6.0 and a 25:1 cobalt to DNPP ratio (5 × 10 −5 M DNPP) the observed acceleration over hydrolysis in the absence of the cobalt complex is ∼3 × 10 3 ; the calculated specific rate constant for hydrolysis in the reactive 1:1 complex ( k ∼0.2 s −1 ) represents an acceleration over the unpromoted rate of ∼3 × 10 4 .
TL;DR: In this paper, it was shown that by enlarging the number of anticommuting coordinates in Parisi-Sourlas type of supersymmetry, one naturally obtains dimensional reduction from a D to a D -2 M theory (M integer) to all orders of perturbation theory.