Executive Summary : | Novel designs of azoheteroarene-based photoswitches are proposed to use them as photoswitchable catalysts. Designing molecular systems mimicking enzymes and enabling stimuli responsiveness to them are some of the critical challenges in catalysis. Light is one of the most profoundly used stimuli, mainly for its fast and real-time responsiveness, non-destructive nature, and remote assistance. Such light-modulated artificial catalysts allow precision control in the reactivity temporally (reaction rates) and spatially (regio- and stereo aspects) through the exploitation of different states of the photoswitchable catalysts. Despite reasonable progress in this thrust area, enormous insights are still in demand for better spatial- and temporal control. Particularly the recent advancement and versatility in the utility of azoheteroarene photoswitches permit improved designs and better photoswitchable catalysts. Besides that, the heterocycle part of those photoswitches renders additional handles in making them ionic and coordinated to metal centers, which are lesser known. Utilizing the concepts learned and the properties observed during the recent investigations on azoheteroarene photoswitchable molecular systems in the PIs lab, diverse approaches in bringing phototunability of catalysis are envisioned. The designs include catalysis through non-covalent interactions such as hydrogen bonding, anion binding, and metal-based activation. Along the line, attempts will also be made to introduce specific functional groups as a part of photoswitch to enable bifunctionality. All these catalysts are expected to show varied effects ranging between ON-OFF modulation, reaction rate control, and stereo control of the reactions and products by light. The photoswitchable catalysis will be tested for standard reactions and further explored for new reactions developed in the Co-PI's lab, which are unproven in this domain. Based on the explorations using the preliminary designs of the catalysts, improvement in the catalytic activity and light control in selectivity will iteratively be achieved by redesigning. In addition, a recent finding on light-modulated dissolution/precipitation will be used to recover and recycle the catalyst. All the mechanistic investigations will be appropriately studied using spectroscopy and computations. The project's primary goal is to design an ideal photoswitchable catalyst (either through organocatalysis or by metal catalysis) to improve the on/off ratio and tune the product selectivity by light. The culmination of all significant outcomes of the project is expected to overcome the traditional drawbacks of H-bond donor and anion binding catalysis and newer perspectives to metal-based catalysis. |