Bioinspired Binding and Conversion of Linear Monoterpenes by Polyaromatic Coordination Capsules

Area of Science:

• Supramolecular Chemistry
• Organic Synthesis
• Catalysis

Background:

• Natural enzymes exhibit remarkable selectivity in converting linear monoterpenes to cyclic compounds.
• Synthetic systems often struggle to replicate this enzymatic efficiency and selectivity.
• Developing artificial systems to mimic terpene biosynthesis is a significant challenge.

Purpose of the Study:

• To design and synthesize polyaromatic coordination capsules capable of binding and transforming linear monoterpenes.
• To demonstrate the selective binding and catalytic activity of these capsules in both solution and solid states.
• To explore the potential of these synthetic cavities in mimicking terpene biosynthesis.

Main Methods:

• Formation of polyaromatic coordination capsules via self-assembly of Pt(II) ions and bent bispyridine ligands.
• Selective binding studies of citronellal from mixtures and preferential vapor binding.
• Catalytic cyclization-dimerization of citronellal within the capsule using an acid catalyst.
• Characterization of products and assessment of reaction yield and stereoselectivity.

Main Results:

• The synthetic capsules selectively bind citronellal from mixtures and show preferential binding in the vapor phase.
• The capsules efficiently extract p-menthane-3,8-diol from reaction mixtures with high product and stereoselectivity.
• Catalytic cyclization-dimerization of vaporized citronellal within the acid-loaded capsule yields p-menthane-3,8-diol citronellal acetal with high yield (>330%).
• The capsule reactor demonstrates reusability for at least 5 cycles with enhanced conversion.

Conclusions:

• Bioinspired synthetic polyaromatic cavities can effectively mimic natural enzymes in binding and transforming linear monoterpenes.
• These capsules offer a novel platform for selective synthesis and mimicry of terpene biosynthesis.
• The developed system provides an efficient and reusable catalytic reactor for valuable chemical transformations.