There are already excellent examples of what conventional (non-porous) liquid solvents can achieve in industrial processes such as 'wet-scrubbing' for CO2 capture, which involves aqueous amine solutions to chemically absorb CO2. However, this typically requires large amounts of energy to regenerate the liquid. Porous liquids, on the other hand, might be adapted into existing infrastructure that uses conventional flow processes, while also lowering the energy penalty of solvent regeneration by exploiting physisorption rather than chemisorption. In addition, the incorporation of discrete molecules or frameworks into a liquid also adds the potential for shape and size specificity, allowing porous liquids to be tailored towards target separations and applications. To date, porous liquids have been mostly studied for their ability to absorb gas, and only a handful of materials have been explored for gas selectivity. So far, little research has gone into understanding the gas release mechanisms of porous liquids. Several methods for controlled gas release from porous liquids have been reported, each providing its own challenges. As for porous solids, the most common gas release mechanisms are pressure and temperature swings. This significantly limits the solvent choice in a porous liquid, restricting us to solvents that have a low or (ideally) near-zero vapour pressure. There is also a significant parasitic energy penalty with pressure and temperature swings. Moreover, some materials might not be stable to temperature swings; for example, it was reported that some porous liquids are unable to withstand temperature displacement over multiple cycles. An alternative method to release gases is based on guest exchange by chemical displacement, where the addition of a small molecule with a more favourable binding in the cavity is used to displace the gaseous guest from the pores. While effective in the laboratory, this method has very limited practical appeal because the displacing molecule is harder to remove than the gas. Lastly, sonication has been used to release gaseous guests from porous liquids. While this method is a non-invasive alternative to chemical displacement, the relative parasitic energy costs are as yet unclear and more problematically, sonication may be undesirable for large scale processes (e.g., cavitation can damage metal containment vessels). Here, we investigate the formation of photoresponsive type III porous liquids. We exploited well-known photochromic molecules, azobenzene and 1,2-bis(4-pyridyl)ethylene, both of which have been incorporated into a zinc-based MOF (Figure ) that is capable of efficient and reversible cis to trans photoisomerisation when exposed to UV or visible light (trans: max ≈ 370 nm, cis max ≈ 460 nm). This system was previously reported by Chen et al. and later studied by Lyndon et al. for its dynamic photoswitching in the solid state; specifically a change in CO2 uptake was reported upon photoswitching. By dispersing this photoresponsive MOF in an ionic liquid as the size-excluded solvent, we have developed a new Type III porous liquid, creating what we believe to be the first proof-of-concept photoresponsive porous liquid that is capable of selective gas uptake and UV light-triggered release (Figure ).