Absolute chiral environments are rare in regular polyhedral and prismatic architectures, but are achievable from self-assembly of metal–organic cages/containers (MOCs), which endow us with a promising ability to imitate natural organization systems to accomplish stereochemical recognition, catalysis and separation. Here we report a general assembly approach to homochiral MOCs with robust chemical viability suitable for various practical applications. A stepwise process for assembly of enantiopure ΔΔΔΔΔΔΔΔ- and ΛΛΛΛΛΛΛΛ-Pd₆(RuL₃)₈ MOCs is accomplished by pre-resolution of the Δ/Λ-Ru-metalloligand precursors. The obtained Pd–Ru bimetallic MOCs feature in large D₄-symmetric chiral space imposed by the predetermined Ru(II)-octahedral stereoconfigurations, which are substitutionally inert, stable, water-soluble and are capable of encapsulating a dozen guests per cage. Chiral resolution tests reveal diverse host–guest stereoselectivity towards different chiral molecules, which demonstrate enantioseparation ability for atropisomeric compounds with C₂ symmetry. NMR studies indicate a distinctive resolution process depending on guest exchange dynamics, which is differentiable between host–guest diastereomers.

Photocatalytic water splitting is a natural but challenging chemical way of harnessing renewable solar power to generate clean hydrogen energy. Here we report a potential hydrogen-evolving photochemical molecular device based on a self-assembled ruthenium–palladium heterometallic coordination cage, incorporating multiple photo- and catalytic metal centres. The photophysical properties are investigated by absorption/emission spectroscopy, electrochemical measurements and preliminary DFT calculations and the stepwise electron transfer processes from ruthenium-photocentres to catalytic palladium-centres is probed by ultrafast transient absorption spectroscopy. The photocatalytic hydrogen production assessments reveal an initial reaction rate of 380 μmol h⁻¹ and a turnover number of 635 after 48 h. The efficient hydrogen production may derive from the directional electron transfers through multiple channels owing to proper organization of the photo- and catalytic multi-units within the octahedral cage, which may open a new door to design photochemical molecular devices with well-organized metallosupramolecules for homogenous photocatalytic applications.

In this paper, we report the design and synthesis of two pyridyl-substituted tripodal ligands, 3-TPyMNTB (tris(((pyridin-3-ylmethyl)benzimidazol-2-yl)methyl)amine) and 4-TPyMNTB (tris(((pyridin-4-ylmethyl)benzimidazol-2-yl)methyl)amine). Reaction of these two ligands with Eu(III)/Tb(III) picrate salts gives mononuclear complexes [Eu(3-TPyMNTB)(pic)₃]·2H₂O (1) and [Tb(3-TPyMNTB)(pic)₃]·2H₂O (2), respectively. While reaction with Eu(III)/Tb(III) nitrate salts leads to cocrystallization of a coordinative motif and an inorganic salt in one single-crystal, namely, [Eu(3-TPyMNTB)(NO₃)₃]·0.5[Eu(NO₃)₃(H₂O)₄]·3CH₃CN (3), [Tb(3-TPyMNTB)(NO₃)₃]·0.5[Tb(NO₃)₃(H₂O)₄]·3CH₃CN·1.5C₂H₅OH (4), [Eu(4-TPyMNTB)(NO₃)₃]·[Eu(NO₃)₃(H₂O)₃]·3CH₃CN·0.5H₂O (5) and [Tb(4-TPyMNTB)(NO₃)₃]·[Tb(NO₃)₃(H₂O)₃]·3CH₃CN·0.5H₂O (6). In these cocrystals, the organic ligand-coordinated motif [Ln(3(4)-TPyMNTB)(NO₃)₃] and the nitrate anion-bonded motif [Ln(NO₃)₃(H₂O)_n] (Ln = Eu(III) or Tb(III), n = 3 or 4) provide two Eu(III)/Tb(III) centers which coexist in the same crystal lattice. Of most interest, both coordinative and inorganic centers can be excited by the absorption of the organic ligand, that is, the double luminescent centers in the cocrystalline systems can be sensitized by the same antenna source. Therefore, both Dexter and Förster mechanisms are proposed to be involved in the emission process, in which the energy transfer is conducted either through direct bond linkages or through space from unlinked organic antennae.