Kinetics temperature jump

Markwalder B, Gozel P and van den Berg H 1992 Temperature-jump measurements on the kinetics of association and dissociation in weakly bound systems N2O4 + M = NO2 + NO2 + M J. Chem. Phys. 

A large programme utilizing temperature-jump relaxation methods for the study of tautomerism in aqueous solution has led the Dubois group to determine the kinetic and thermodynamic parameters of the equilibrium (130a) (130b) (78T2259). The tautomeric... 

Temperature-jump experiments showed an evident increase of the rate of transition by using methanol as solvent instead of water. According to Fig. 31, this is mainly caused by the increase of the fast kinetic phase at the expense of the following slow phase. 

Temperature-jump kinetics. The kinetics of complexation of lutetium(III) with anthrani-late ion was studied by the use of a temperature-jump method.25 The principal reaction is... 

Taft equation, 229-230 Temperature, effect on rate, 156-160 Temperature-jump method, 256 Termination reaction, 182 Thermodynamic products, 59 Three-halves-order kinetics, 29... 

Desorption Rates. Using the above model for the temperature jump associated with pulsed laser heating, the rate of desorption versus time and the total number of molecules desorbed from a finite surface area heated by the laser can be calculated. For the particular case of first-order desorption kinetics, the desorption rate is ... 

The physical reason for the velocity slip is the fact that close to the wall the gas is not in thermal equilibrium. For the same reason, a temperature jump is induced, and a more detailed investigation based on the kinetic theory of gases shows that heat transfer and momentum transfer are coupled. Expressions for velocity slip and temperature jump valid in the case of non-isothermal conditions are given by... 

Ferrone FA, Hofrichter J, Eaton WA. Kinetics of sickle hemoglobin polymerization. I Studies using temperature jump and laser photolysis techniques. J Mol Biol 1985 183 591-610. 

Polyether complexation. The kinetics of formation of polyether crown, cryptand and related complexes have received considerable attention. Since formation rates are often quite fast, techniques such as temperature-jump, ultrasonic resonance, and nmr have typically been used for such studies. 

The first experimental data for a reaction involving proton transfer from a hydrogen-bonded acid to a series of bases which were chosen to give ApK-values each side of ApK=0 are given in Fig. 15 (Hibbert and Awwal, 1976, 1978 Hibbert, 1981). The results were obtained for proton transfer from 4-(3-nitrophenylazo)salicylate ion to a series of tertiary aliphatic amines in aqueous solution, as in (64) with R = 3-nitrophenylazo. Kinetic measurements were made using the temperature-jump technique with spectrophoto-metric detection to follow reactions with half-lives down to 5 x 10"6s. The reciprocal relaxation time (t ), which is the time constant of the exponential... 

The kinetics of proton transfer from protonated 1,8-bis(dimethyl-amino)-2,7-dimethoxynaphthalene to substituted phenolate ions (69) were studied in 70% (v/v) Me2SO—H20 using the temperature-jump technique with spectrophotometric detection to follow reactions with half-lives in the range 1-100 ms (Hibbert and Robbins, 1978). A limited... 

Results which have an important bearing on the mechanism of proton removal from intramolecular hydrogen bonds have been obtained quite recently for the second ionisation of phenylazoresorcinols (73). Kinetic measurements were made using the temperature-jump technique (Perlmutter-Hayman and Shinar, 1975 Perlmutter-Hayman et al., 1976). 

At low hydroxide-ion concentrations, the rate of approach to equilibrium after a temperature jump decreases as the hydroxide-ion concentration increases. At higher concentrations the reaction becomes first order in hydroxide ion. The value of the kinetic solvent deuterium isotope effect on the reaction shows little variation over the range of hydroxide-ion concentrations studied as shown in Fig. 19. The ratio t-1(H20)/t 1(D20) at a particular concentration of OL (L = H or D) remains within the range 2.0 to 3.0 for OL" concentrations of 0.001 to 0.100 mol dm - 3 and provides little mechanistic information. Similar results were obtained in the original work (Perlmutter-Hayman and Shinar, 1978). 

The most common methodology for measuring fast kinetics in real time is to perturb a system at equilibrium for a time duration that is much shorter than the relaxation kinetics that follow perturbation. This perturbation can be achieved by changing the concentration of chemicals through fast mixing (stopped-flow), changing the temperature of the solution (temperature jump), simultaneously changing the... 

Temperature jump studies were performed in combination with stopped-flow experiments94 in response to criticism as to the reliability of temperature jump experiments26,142 and divergent interpretation of the kinetics. In particular, the suggestion from pressure jump experiments that the association step is diffusive in nature... 

The values for k+ and k were compared for temperature jump and stopped-flow conditions for DNA concentrations where the decay followed a mono-exponential function and no migration between DNA molecules occurred (see below).94 This report shows the importance of detecting fluorescence signals at the magic angle, which eliminated the fast components in the kinetics due to artifacts. The values for the association and dissociation rate constants obtained by both techniques are similar. 

The complexity of the binding dynamics of 1 with DNA became apparent in subsequent temperature jump experiments, where three relaxation processes were observed.112 The fastest relaxation process had a small amplitude (< 14%) and its kinetics were uncoupled from the second and third relaxation processes. This fast process was assigned to the binding of 1 to a minor site with a k+ value of 1.5x10 M s and a value of 6.9 x 10 s. This assignment was problematic because of the possible interference of artifacts for temperature jump experiments when the fluorescence detection is not performed at the magic angle,29 and this kinetic component was not observed in later studies.94,120... 

Finally, no dependence on the temperature, DNA concentration and salt concentration was observed for a temperature jump study using ct-DNA that was not sonicated.27 Based on these results the authors concluded that only large-scale dynamics of the DNA were responsible for the binding kinetics of 1 to DNA, and they suggested that studies with short length DNA may not be relevant for in vivo situations. 

Temperature jump studies on the binding dynamics of 5 with ct-DNA and T2 Bacteriophage DNA showed two lifetimes in the relaxation kinetics.117 The observed... 

The non-linear dependence of the relaxation process on the DNA concentration was also observed in stopped-flow experiments and the same mechanism, i.e. fast pre-equilibrium followed by a slow intercalation step, was proposed." This latter study did not report values for the individual rate constants. The mechanism proposed in Scheme 4 was employed in subsequent studies despite the criticism on the accuracy for the data related to the fast kinetic component (see below). The original temperature jump study also showed that the relaxation kinetics depend on the structure of the DNA.117 The slower intercalation rate for 5 with T2 Bacteriophage DNA when compared to ct-DNA was ascribed to the glucosylation of the former DNA (Table 3). 

The kinetics of a series of guests that form 2 1 (guest CD) complexes were studied using temperature jump methods.179 183,210 The formation of the 1 1 complex was determined to be fast and to occur within the time resolution of the equipment, while... 

DR. THOMAS The kinetic parameters of micelles are very well known, having been determined by temperature-jump relaxation methods and various other techniques. There are several kinetic events which can be described. First of all, the fastest event is the exchange of the counter ion (e.g., the sodium counter ion, in sodium lauryl sulfate). These ions exchange... 

Fig. 9. Average values of the kinetic energy for LIF-LID studies of NO/Pt(foil) as a function of temperature jump (T, , = 200 K). The lower set of data correspond to the thermal channel the upper to the non-Boltzmann channel.

In recent years, evidence has been found that both mechanisms of proton transfer can occur for certain intramolecularly hydrogen-bonded acids. Also, new kinetic behaviour has been obtained which allows a much more detailed examination of the reaction steps in (22). Kinetic data for the second ionization of substituted phenylazoresorcinols in the presence of hydroxide ions (25) were some of the first to be obtained for an intramolecularly hydrogen-bonded acid. The reciprocal relaxation time (t ) for the approach to equilibrium in a temperature-jump experiment was measured at different hydroxide-ion concentrations. A linear dependence of x on [OH] was obtained of the form of (26) (Eigen and Kruse, 1963 Inskeep et al., 1968 Rose and Stuehr, 1971). However, careful measurements at lower hydroxide-ion concentrations (Perlmutter-Hayman and Shinar, 1975 Perl-mutter-Hayman et al., 1976 Yoshida and Fujimoto, 1977) revealed that the... 

---