Stopped flow high pressure

S. Funahashi, K. Ishihara, S. Aizawa, T. Sugata, M. Ishii, Y. Inada, M. Tanaka 1993, (High-pressure stopped-flow nuclear magnetic resonance apparatus for the study of fast reactions in solution), Rev. Sci. Instrum. 64, 130. 

Other high-pressure stopped-flow/CL systems are based on special mixing modes, the main technical difference of which is that the CL observation cell... 

High pressure stopped-flow (hpsf) apparatus, 13 421-424 disadvantages of, 13 422 High pressure temperature-jump apparatus, 13 427... 

K. Ishihara, H. Miura, S. Funahashi and M. Tanaka, Inorg. Chem. 27, 1706 (1988), describe a high-pressure, stopped-flow arrangement with conductivity monitoring. 

FIGURE 7.4 TgK (High Tech) scientific high-pressure stopped-flow. 

There is a marked contrast between zinc and cadmium in the context of complexing of the 2+ ions with bipy, studied by high-pressure stopped-flow. There is a striking difference between the two elements, with Zn + reacting progressively more slowly with bipy as pressure increases, Cd + more rapidly. The Activation Volume (Ay ) for the zinc reaction is -1-7.1 cm mol whereas for cadmium the value is -5.5 cm mol . These values suggest that the substitutions are 7d and 4 in character respectively. AT values for the reverse, dissociation, reaction and A " values for formation and for dissociation, are all consistent with this assignment of mechanism. Positive activation volumes for a few other substitution reactions at Zn +aq also indicate h mechanisms, as proposed many years ago in discussions of ultrasonic data on complex formation from Zn +aq. 

The influence of temperature can be studied, and the activation parameters (e g. the activation enthalpies and entropies) can be calculated. If necessary, the high-pressure stopped-flow technique can be used to study the pressure dependence of reactions, and the corresponding volumes of activation may be calculated. 

Kissner, R., Nauser, T, Bugnon, P, Lye, PG, and Koppenol, WH. 1997. Formation and properties of peroxynitrite as studied by laser flash photolysis, high-pressure stopped-flow technique, and pulse radiolysis. Chem Res Toxicol 10 1285-1292. 

High pressure stopped-flow experiments upon the reaction of hexaaquairon(III) and promazine (R = CH3CH2CH2N(CH3)2, see reaction given below) yielded AV values of -6.3 and -12.5 cm mof for the forward and reverse reactions, respectively. [139] The derived reaction volume of 6.2 cm mof has been confirmed by calculation from the pressure dependence of the equilibrium constant obtained from the variation of the UV/Visible spectra as a function of pressure. The volume profile (see Figure 9) displays the fact of a compact transition state, and the positive reaction volume was suggested to arise from charge dilution in proceeding from the reactants to Fe(aq) and the promazine cation radical. 

A high-pressure stopped-flow technique [22] was applied to study the complex formation reactions between [Pt(L)(H20]+ and Nj" or tmtu, where L = C6H3(CH2NMe2)2-2,6 [23] or N,N-dimethylbenzylamine and pyridine-3-sulfonic acid [24], tmtu = N,N,N, N -tetramethylthiourea. The large negative activation volumes found for the forward and reverse reactions (AV values are between —10.1 and —12.4 cm3moN1) are evidence for the operation of an associative activation mode for the substitution. 

Procedures for filling the high-pressure stopped-flow instrument in Fig. 6.9 (the numbers in parentheses are the numbered parts in Fig. 6.9)... 

High-pressure stopped-flow spectrometer and spectrophotometer units to 2 kbar and 10 ms... 

The development of high pressure stopped-flow instruments opened up the possibility to study reactions in the millisecond and second time range as a function of pressure [21-27]. A stopped-flow instrument is designed to enable the rapid... 

Fig. 1.6. Schematic representation of a high pressure stopped-flow unit 1 - lid to overall unit 2 - outer vessel 3 - window holder 4 -quartz windows 5 - electric motor 6 - motor actuator 7 - stopped-flow unit positioning...

Fig. 1.7. Schematic representation of the commercially available Hi-Tech HPSF-56 high pressure stopped-flow unit [28].

Pressure effects on the reaction of NO with metmyoglobin (Eq. 6.45) has also been studied by laser flash photolysis and by high pressure stopped flow reactions [%]. 

High-pressure stopped-flow kinetic measurements were performed up to 200 MPa. The observed rate constants, ki,obs and k2,obs as a function of pressure and a-CD concentration, were fitted simultaneously according to the reaction scheme shown in Fig. 11.8 leading to the microscopic rate constants kij, k2,f, h,r and fe2,r-The results are summarized in the form of volume profiles in Fig. 11.10. 

The study of the dynamics of host-guest interaction can be subdivided into three aspects the kinetics of complexation, the flexibility of the host, and the dynamics of the guest. A method based on high-pressure stopped-flow kinetics/UV-Vis absorption spectroscopy has been described for the investigation of the kinetics and thermodynamics of the formation of inclusion complexes between phenylazo dyes and a-CyD [49]. Time-resolved measurements of excited-state evolution could be... 

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