Development of New Technique to Probe Rapid ReactionsAfter Dissolution of Solids

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In this project, efforts have been made to develop a new instrument that enables the detection of an extremely rapid reaction that takes right after dissolution of a solid sample. The fundamental concept is very simple and is to develop a 'flash-solid-dissolution equipment' facilitating not only a prompt dissolution of a solid but also a prompt filtration for the removal of undissolved solid at the same time. To this end, experiments were carried out to find out an appropriate method offiltration. As a result, we found that a Teflon wool is a good candidate. We further endeavored to design to construct the main part of the above mentioned dissolution equipment. In our equipment, a solution is rapidly transferred into a solid-dissolution room equipped with a filtration facility. Injection is carried out by use of air pressure of about 3 atm. A freshly prepared filtrate is simultaneously transferred into an optical measurement cell. Finally, a rapid chemical reaction that takes place immediately after the dissolution event can be monitored by use of a multi-channel photodiode array spectrophotometer to analyze the kinetics of the reaction. In our new equipment, it is possible to minimize the dead time corresponding to the unobservable time domain into ca. 0.5 sec or so. With this methodology, we have succeeded in observing a very rapid reaction that takes place after dissolution of a mixed-valence tetranuclear platinum complex. We have been for a long time unaware of this reaction. Thus we have demonstrated that such an approach is indeed valid to better understand the chemical phenomena that are occurring right after dissolution of a certain chemical into a solution.