Enhancing the Catalytic Activity in the Solid State: Metal–Organic Frameworks to the Rescue

With a double life as an indispensible consumer commodity but also an environmental scourge, plastics are omnipresent in the modern age, produced at massive scales and a constant source of political and societal debate. Compared to the commonly used polypropylene-based plastics, polyester plastics using poly((R)-β-hydroxybutyrate) (PHB) are biodegradable and therefore have much less of a harmful environmental impact. Widespread use of PHB is, however, limited as the polyester is typically biosynthetically produced from the microorganism Alcaligenes eutrophus, resulting in a market cost ∼16× greater than that of polypropylene. As an alternative proposed pathway, the ring-opening polymerization of β-lactones offers many promising advantages over the biosynthetic route. Historically, β-lactones have been predominantly synthesized via either a [2 + 2] cycloaddition reaction or cyclization of β-halosalts. Because of low yields, these processes are not compatible with large-scale industrial practices consequently resigning β-lactones as niche reagents for natural product syntheses. However, the seminal works by Apler et al. and later Coates et al. demonstrated that by combining a Lewis acid with a cocatalyst Co(CO)4 –