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  • 03월 02일 17시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제109회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Effect of Assisted-Waters in Rate Constant and Kinetic Isotope Effects of Tautomerization of Formic Acid and Formamidine: Direct ab initio Dynamics Study

2012년 2월 22일 17시 25분 58초
PHYS.P-504 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
4월 25일 (수요일) 18:00~21:00
저자 및
Mai Khanh Binh
경희대학교 Chemistry, Vietnam

The mechanism and dynamics of the double proton transfer in hydrated formic acid (FA) and formamidine (FM) complexes were performed by using direct ab initio dynamics approach with variational transition-state theory using multidimensional semiclassical tunneling approximation. Double proton transfer processes of hydrated FA complexes tend to occur in protolysis mechanism. Besides that, solvolysis fashion is the interested one of hydrated FM systems. The effect of assisted-waters, hydrogen bond accepting water - aW - and hydrogen bond donating water - dW - were also investigated. With hydrated FA complexes, aW has a positive effect. It means that aW reduces the barrier height, and the tautomerization process becomes faster. The same effect is also found with dW in hydrated FM cases. On the other hand, dW in hydrated FA and aW in hydrated FM have an opposite trend, increase activation energies and reduce rate constants. Kinetic isotope effects (KIEs) were also calculated. Primary KIEs agree well with experiment values and previous calculated result. Except monohydrated FM system, tunneling contribution to the primary KIE is not much large. It means that two deuteriums can also tunnel well. Solvent KIEs have small value, because of the hydrogen of assisted-water do not involve directly in proton transfer processes. The quasiclassical effect is the dominant contribution to the primary KIE and solvent KIE, the changing of entropic contribution mostly affect to the KIEs.