T-Jump Studies

The existence of dimeric and polymeric species in aqueous solutions of indium(m) and thallium(iii) has an effect on kinetics of systems which include these reactants. A T-jump study of indium(iii) perchlorate solution has yielded a value for the rate constant for dimerisation of [InOH] +. Due to ion-pairing complications, it has not proved possible to determine unequivocally, by comparison of rate constants of this and of the indium(m)-sulphate system, whether the rate-determining step in dimerisation of [InOH] + is loss of a solvating water molecule from the indium. The situation is entirely similar for gallium(iii) in perchlorate solution. ... 

Rates of formation, and of dissociation, of dimeric iron(m) complexes of cydta, edta, and hedta have been determined as a function of pH. This represents a contribution to the knowledge of the kinetic behaviour associated with M-O-M and M-OH-M systems, to complement the long-known thermodynamic properties of such complexes. T-Jump studies of the dimerisation of iron(m)-edta show one relaxation, ascribed to the equilibrium... 

We also include some T-jump studies specifically performed on systems of giant micelles. 

Lp—> L transition was found to be completed within 37 s with a nonexponential course, while the L —> Lp< transition was complete in less than 13 s. These times are much longer than those measured in T-jump studies and according to the authors the difference probably arose from a disparate experimental protocol. Cheng et al. ° reexamined the kinetics of the Lp-->L and L ->Lp-transitions by p-jump coupled to TR-SAXS. They reported still shorter times for the transitions, less than 50 ms and about 1 s, respectively, and concluded that the transitions were of the two-state type. Note that the perturbation of the system in the T-jump studies was of much larger amplitude than in the p-jump studies. This probably affected the absolute values of the reported transition times. The effect of the amplitude of the perturbation on the measured times is further discussed below. 

Naraghi, M. T-jump study of calcium binding kinetics of calcium chelators. Cell Calcium 1997, 22, 255-268. 

Molybdenum. The protonation of the [MoOJ" anion, determined by ultrasonic techniques, is about ten times slower than that of the [MovOaJ anion. This difference is ascribed to the necessity of changing the stereochemistry about the molybdenum from tetrahedral to octahedral on adding H+ to the [MoOJ" anion." T-Jump studies of molybdate solutions show two relaxations. 

Gross, H. and Geier, G. (1987) Kinetics and equilibria of mercury(II) complexes with phenanthroline, bipyridyl and OH in aqueous solution. T-jump study with a novel computational technique for multi-step relaxation processes. Inorg. Chem., 26, 3044-3050. 

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