Cryptophanes are molecular capsules composed of cyclotriveratrylene (CTV) units. Hemicryptophanes, derived from cryptophanes, feature an alternative moiety in place of one CTV unit, expanding design possibilities. Our recent work highlights hemicryptophane L, which forms air-stable Cu(I) complexes capable of binding CO—an uncommon phenomenon.

To investigate the role of methoxy groups on the CTV unit of hemicryptophane L on Cu(I) binding, interactions with CO, and air stability, we designed hemicryptophane L2. Removing these methoxy groups from L's CTV cap might alter the accessibility of the capsule, influencing air-stability.

L2 was synthesized in four steps from 3-methoxybenzylalcohol. L2 synthesis faces challenges in step 1 which are marked by unwanted polymerization. Despite scaled-down, optimized conditions, yield improvement remains difficult. While step 2 shows better yields, step 4 involves large macrocycles and suffers from entropic challenges and polymer formation, restricting yield.

Once more pure L2 is obtained, our focus will shift to acquiring an x-ray crystal structure of L2 for structural comparison with L. 

Next, we aim to synthesize and purify a copper (I)-bound L2 complex for CO binding and air-stability comparison against L. Once pure Cu(I)-bound L2 is obtained, we will attempt crystallization to attain its x-ray crystal structure for direct comparison with Cu(I)-bound L.

Finally, we will explore CO binding with Cu(I)-bound L2, hypothesizing that methoxy group elimination will alter CO binding dynamics. This investigation will unveil the effects of structural modifications on guest interactions.

In conclusion, our research delves into hemicryptophane-based complexes, shedding light on their structure, Cu(I) binding, and guest interactions. Hemicryptophane L2's design offers a unique platform to probe how methoxy groups influence stability and accessibility.