Qi Yuan

Project: The development and application of quantum chemistry based tools to predict the photochemical stability and photoproducts of herbicides

The ability to predict the photochemical stability of herbicides, and the potential photoproducts that they can produce is of significant interest to the agrochemical industry. The current mechanism for assessing the photochemical stability of potential herbicides is to deposit the material as a thin film upon a glass slide and to measure its stability upon irradiation by sun lamp. Whilst this experimental technique affords a degree of standardisation, in the form of a defined surface and solvent, it is far from the environment that the herbicide would encounter when deposited on the waxy surface of a leaf. The residency time of the herbicide on the leaf is of importance, as is its stability to exposure to UV and visible light. The photochemical stability of all molecules is inherently a function of their electronic ground and excited states, which are in turn determined by quantum mechanics.

This innovative project will determine whether commonly available quantum chemical methods for calculating ground and excited states of molecules can be utilised to determine physicochemical descriptors that can be used in a predictive manner to determine the photochemical stability of potential herbicides