Stepwise synthesis of nanosized Pd-Ru heteronuclear metal-organic cages from predesigned redox- and photo-active Ru(II)-metalloligand and naked Pd(II) ion is described. The resulting cage shows rhombododecahedral shape and contains a 5350 Å(3) cavity and 12 open windows, facilitating effective trapping of both polar and nonpolar guest molecules. Protection of photosensitive guests against UV radiation is studied.

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.

The photoinduced regio- and enantioselective coupling of naphthols and derivatives thereof is achieved in the confined chiral coordination space of a Ru metalloligand based cage. The racemic or enantiopure cages encapsulate naphthol guests, which then undergo a regiospecific 1,4-coupling, rather than the normal 1,1-coupling, to form 4-(2-hydroxy-1-naphthyl)-1,2-napthoquinones; moderate stereochemical control is achieved with homochiral cages. The photoreactions proceed under both aerobic and anaerobic conditions but through distinct pathways that nevertheless involve the same radical intermediates. This unusual dimerization constitutes a very rare example of asymmetric induction in biaryl coupling by making use of coordination cages with dual functionality-photoredox reactivity and stereoselectivity.

The stereochemistry of chiral-at-metal complexes is much more abundant, albeit complicated, than chiral-at-carbon compounds, but how to make use of stereolabile metal-centers remains a formidable challenge due to the highly versatile coordination geometry of metal ions and racemization/epimerization problem. We demonstrate herein a stepwise assembly of configurationally stable [Pd 6 (FeL 3 ) 8 ] 28+ (Δ/Λ-MOCs-42) homochiral octahedral cages from unstable D 3 -symmetry trischelate-Fe type metalloligands via strong face-directed stereochemical coupling and facile chiral-induced resolution processes based on stereodifferentiating host−guest dynamics. Kinetic studies reveal that the dissociation rate of MOC-42 cages is 100-fold slower than that of Femetalloligands and the racemization is effectively inhibited, making the cages retain their chirality over extended periods of time (>5 months) at room temperature. Recyclable enantioseparation of atropisomeric compounds has been successfully achieved, giving up to 88% ee.

A photochromic metal-organic gel with thermo-, photo-, and anion-responsive behavior is obtained. Unusually, heating of the Al-ligand solution leads to gel formation and cooling to room temperature reverses the process to reform the solution. The gel is sensitive to weakly coordinating anions. Additionally, reversible photochromic transformations take place both in the solution and gel states, accompanied by reversibly switched luminescence.

An anocage coupling effect from ar edoxR u II -Pd II metal-organic cage is demonstrated for efficient photochemical H 2 production by virtue of redox-guest modulation of the photo-induced electron transfer (PET) process. Through coupling with photoredox cycle of MOC-16, tetrathiafulvalene (TTF) guests act as electron relaym ediator to improve the overall electron transfer efficiency in the hostguest system in al ong-time scale,l eading to significant promotion of visible-light driven H 2 evolution. By contrast, the presence of larger TTF-derivatives in bulk solution without host-guest interactions results in interference with PET process of MOC-16, leading to inefficient H 2 evolution. Suchi nteraction provides an example to understand the interplay between the redox-active nanocage and guest for optimization of redox events and photocatalytic activities in ac onfined chemical nanoenvironment.

Multicolored photoluminescence tuning in a single-phase material has invaluable potential in display and security applications. By deliberate design of a multifunctional antenna ligand and precise control of mixed metal ionic compositions in lanthanide metal-organic frameworks (Ln-MOFs), we achieved dichromatic fine-tuning among red, green, or blue primary colors through growth of a series of isomorphous Ln-MOF crystals·solvents of formula [LnnLn'1-n(TTP)2·H2O]Cl3 (Ln = Ln' = Eu, Tb, and Gd, 1-3; Ln = Eu, Ln' = Tb, 4-8; Ln = Gd, Ln' = Eu, 9-11; Ln = Gd, Ln' = Tb, 12-14; 0 < n < 1; TTP = 1',1″-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tris(pyridine-4(1H)-one)). The linear dependence of the emissions were analyzed, and the mathematical matrix models were established, which are useful to control the synthetic conditions and to predict the color chromaticity coordinates under varied excitation wavelengths. The potential relevance of these multicolored photoluminescent Ln-MOFs to barcoded materials was demonstrated.

A new bifunctional NTB (tris(benzimidazol-2-ylmethyl)amine)-type ligand incorporating coordination discriminable tripodal benzimidazolyl and monodentate pyridyl groups, tris((pyridin-3-ylmethyl)benzoimidazol-2-ylmethyl)amine (3-TPyMNTB), has been prepared to assemble 4d–4f heterometallic three-dimensional metal–organic frameworks (MOFs) in a stepwise route: (1) direct reaction of 3-TPyMNTB with Ln(ClO4)3 affords monomeric complexes [Eu(3-TPyMNTB)2](ClO4)3·2.5MeCN (1-Eu) and [Gd(3-TPyMNTB)2](ClO4)3·2MeCN·2CHCl3 (1-Gd), and (2) assembly of the precursors 1-Eu and 1- Gd with AgClO4 gives rise to infinite MOFs [EuAg3(3-TPyMNTB)2(H2O)(MeCN)](ClO4)6·4MeCN (2-Eu-Ag) and [GdAg3(3-TPyMNTB)2(H2O)(MeCN)](ClO4)6·4MeCN (2-Gd-Ag), respectively. In monomer 1-Eu, the ligand shows an antenna effect to transfer absorbed energy to Eu3+ center to emit characteristic red luminescence, while in 4d–4f heterometallic MOF 2-Eu-Ag, the ligand centered emission is resensitized by Ag+ ions to generate dual emissions, coming up with the direct white-light emission from a single crystal. The detailed photoluminescent study has been carried out in both solid state and solution to elucidate the emission nature.