Investigating structure dynamics of small molecular systems using time-resolved x-ray solution scattering

Abstract

This thesis deals with the structural dynamics of photolysis of iodoform (CHI3) using time-resolved x-ray solution scattering. Iodoform has been attracted much of attention as it is used as a precursor to an iodopropantion reaction in which photodecomposition under ultraviolet light reacts with an olefin functional group to form a stereoselective cyclic product. In particular, studies have been reported that the stereoselectivity of cyclic compounds produced during the iodopropanation reaction may be due to the unique structure of iso-iodoform, which is one of the photolysis intermediates of iodoform. However in previous studies, the structure of iso-iodoform was solely dependent on theoretical calculations, and the structure of iso-iodoform was not revealed directly. In this thesis, x-rays were used to identify the three-dimensional structure of all intermediates produced during photolysis of iodoform including iso-iodoform, and to propose a new reaction mechanism by capturing the CHI2 radical, which is hard to detect by spectroscopy. Furthermore, by using the x-ray pulses provided by the x-ray free electron laser (XFEL), a time-resolved x-ray solution scattering method based on improved temporal resolution (~ 200 fs) could be attempted, and through this, the process of iso-iodoform formation can also be identified.