Using Light to Control Molecules and Materials

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The proposed research program presents how `designer' molecules can be reversibly modulated with light to be used as detectors for environmental toxins, genes, and other important analytes, probes to monitor the progress of chemical reactions, drug-delivery vehicles, and agents to modify the structural integrity of biomedical devices. Our goal is to control the structure of small molecules, influencing how they behave and interact with their environment. This will be achieved by utilizing `molecular switches' - molecules that respond to different colours of light by reversibly changing their structures in a predictable manner. Traditionally, the emphasis in molecular photoswitching has been on how they absorb light, how they emit light, and how they bend light to advance optoelectronic materials and devices. A much less developed application for molecular photoswitches is how they can conveniently and visually provide information about the presence and the amount of an analyte of interest, how they can inform the user when chemical reactions are complete, and how they can trigger the breakdown of materials whenever the user desires. By utilizing a relatively simple molecule that can undergo a reversible reaction when exposed to two different colours of light and toggle between two unique shapes, we can access many unique properties for a wide range of applications. Since the shape of a molecule dictates how it reacts or interacts with others, the systems developed in this research program will be used to provide information about changes in the environment around them and to change the environment itself. Many of the projects in this program have a common theme - a spontaneous process must first occur before the molecular architecture can change its structure in the presence of light. We call this `chemically-gated' photochemistry and show many ways it can be applied to solve real-world problems such as revealing the presence of a toxic compound that leaks out of our tires, which has recently been shown to pollute waterways and kill resident fish. Another example targets oligonucleotides (DNA and RNA) with the potential to conveniently indicate the presence of specific genes. Similar molecular backbones can also be used to track how close chemical reactions are from being complete, which would simplify the analysis needed in routine synthetic processes. Finally, light will be used to release highly reactive pharmacological species from inactive forms `on-command', and release compounds from their 'delivery vehicles'. The broad real-world applications of this program will place Canadian research at the forefront for solving some of the most pressing health and environmental challenges facing today's society, while training the next generation of innovators and entrepreneurs.