This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A research team has designed and synthesized a molecular cage with an internal cavity by connecting two curved π-conjugated molecules face-to-face at three points. The cage takes up a range of π-conjugated guest molecules through three orifices in its sides and sandwiches them between two π-conjugated panels.
Guests small enough to pass through the orifices can enter and leave reversibly, and bind more strongly as their shapes better match the cavity. Larger guests that cannot pass through the orifices are instead incorporated as the cage is assembled, forming carceplexes from which the guests cannot escape even upon heating under reduced pressure. A distinctive achievement of this study is the permanent encapsulation of planar π-conjugated molecules through molecular shape complementarity, irrespective of the guests' electronic properties—a longstanding challenge.
Because the two π-conjugated panels enclose the guest like armor, the researchers named this molecule "π-Armor." The approach may enable the design of molecular capsules with diverse functions, including the protection of unstable molecules and the development of new molecular materials. The research findings were published online in the journal Journal of the American Chemical Society on Oct. 13, 2026. The field that studies molecules that capture other molecules (hosts) and the molecules they capture (guests) is known as host-guest chemistry.
The ability of one molecule to recognize and bind a particular partner is being studied worldwide because of its potential applications in sensing, separation, catalysis, medicine and many other areas. Hosts capture guests in two principal ways. One is reversible encapsulation, in which a guest repeatedly binds to and dissociates from a host.
The other is permanent encapsulation, in which the guest is incorporated while the host is being assembled and cannot escape afterward. Permanent encapsulation was first reported by Dr. A pioneer of host-guest chemistry, Cram received the Nobel Prize in Chemistry in 1987.
The resulting complexes, known as carceplexes, can perform distinctive functions, such as stably retaining molecules that would otherwise be unstable. Many hosts capable of reversibly capturing planar π-conjugated molecules have been developed using various types of noncovalent interactions. However, very few carceplexes that permanently encapsulate planar π-conjugated molecules have been reported.
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