Aromatic cis-capping ligands reconfigure a coordination cage system for allosterically controlled BODIPY uptake and release
Year: 2026
Type: preprint
Abstract: Biological allostery enables precise molecular recognition and complex function, yet emulating this phenomenon in aqueous synthetic systems remains a significant challenge. Here, we demonstrate that remote cis-capping ligand (L C ) effects can reconfigure a dynamic metal-organic cage (MOC) system for pronounced allosteric guest uptake and release in water. Incorporation of bipyridine (bpy) as L C into a (Pd-L C ) 6 TImB 4 MOC (TImB = 1,3,5-tri(1H-imidazol-1-yl)benzene) shifts the isomer preference from a tube, favored when L C = tetramethylethylenediamine (tmeda), to a capsule-dominated ensemble, while also inducing axial elongation of the minor tube isomer. DFT calculations reveal two remote effects of bpy: (i) TImB planarization is more readily accommodated – a conformation required for capsule isomer; (ii) a broader range of Pd-imidazole rotations are permittable, enabling the minor tube isomer to elongate. A consequence of these effects is a capsule dominated state that hinders the encapsulation of linear aromatic guests, including a water-insoluble BODIPY fluorophore. We show that SO 4 2‒ acts as an exohedral allosteric effector, triggering upregulation of a BODIPY-binding tube state and a pronounced increase in emission. Removal of the effector anion regenerates the non-binding state, promoting slow release of the BODIPY cargo; a process which operates for other linear guests. This work establishes a general strategy based on remote ligand effects and an allosteric anion effector to control molecular catch-and-release in water.
Source: ChemRxiv
Institution: Flinders University
Language: English
Subfield: Organic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7221809546