Organic Chemistry Seminar: Caging alkyl groups to study London dispersion

Abstract:

London dispersion (LD) can give rise to steric attraction, where “bulky” substituents are, counterintuitively, brought together. The scope and magnitude of this attraction are subject to intense debate, however, hindering its widespread application in molecular design.1 This controversy largely results from a lack of systems that probe and quantify LD experimentally, under well-defined conditions.

We employ self-assembled coordination cages2 that confine alkyl groups within their cavity as a platform to study the interactions between these simple groups. Our results show that steric attraction through LD dominates the behavior of these cages, even at the expense of multiple competing driving forces.3,4 Furthermore, by comparing the stability of cages encapsulating diIerent substituents, this system can be used to quantify LD interactions and uncover subtle substituent eIects. Finally, we use these internally alkylated cages to address a long-standing question: can reactions be catalyzed purely through London dispersion?

(1) Wagner, J. P.; Schreiner, P. R. London dispersion in molecular chemistry—reconsidering steric e@ects. Angew. Chem. Int. Ed. 2015, 54, 12274-12296.

(2) Zhang, D.; Ronson, T. K.; Nitschke, J. R. Functional capsules via subcomponent self-assembly. Acc. Chem. Res. 2018, 51, 2423-2436.

(3) Massad, I.; Dobson, J.; Teeuwen, P.; Ronson, T.; Nitschke, J. London dispersion governs stereochemistry, stability, and self-sorting in a system of M4L4 cages. ChemRxiv 2026, doi: 10.26434/chemrxiv-22026-klf26450.

(4) Massad, I.; Agarwal, A.; Lefebvre, C.; Teeuwen, P. C. P.; Ronson, T. K.; Gerbaux, P.; Duez, Q.; Nitschke, J. R. A Zn4L4 cage with guest-programmable stereochemistry. ChemRxiv 2026, doi:10.26434/chemrxiv.15000792/v15000791.

Event Organizer: Dr. Muhammad Jbara