Visible‐Light Photocatalysis of Asymmetric [2+2] Cycloaddition in Cage‐Confined Nanospace Merging Chirality with Triplet‐State Photosensitization

Although the photodimerization of acenaphthylene (ACE) has been known for 100 years, the asymmetric cycloaddition of its 1‐substituted derivatives is unknown. Herein, we report a supramolecular photochirogenic approach in which a homochiral and photoactive Δ/Λ‐[Pd₆(RuL₃)₈]²⁸⁺ metal–organic cage (Δ/Λ‐MOC‐16) is used as a supramolecular reactor for the enantioselective exited‐state photocatalysis of 1‐Br‐ACE. Owing to preorganization of the substrates by the supramolecular cage, stereochemical control of the triplet state, and nanospace transfer of energy and chirality, the cycloaddition of ACE proceeded with high selectivity for the formation of anti over syn stereoisomers, whereas the regio‐, stereo‐, and enantioselective cycloaddition of unsymmetrical 1‐Br‐ACE showed effective enantiodifferentiation of a pair of anti head‐to‐head stereoisomers. The enzyme‐mimicking photocatalysis was verified by catalytic turnover, rate enhancement, and competing‐guest inhibition experiments.     

Host–Guest Recognition and Fluorescence of a Tetraphenylethene-Based Octacationic Cage

We report the synthesis and characterization of a three-dimensional tetraphenylethene-based octacationic cage that shows host–guest recognition of polycyclic aromatic hydrocarbons (e.g. coronene) in organic media and water-soluble dyes (e.g. sulforhodamine 101) in aqueous media through CH⋅⋅⋅π, π–π, and/or electrostatic interactions. The cage⊃coronene exhibits a cuboid internal cavity with a size of approximately 17.2×11.0×6.96 ų and a “hamburger”-type host–guest complex, which is hierarchically stacked into 1D nanotubes and a 3D supramolecular framework. The free cage possesses a similar cavity in the crystalline state. Furthermore, a host–guest complex formed between the octacationic cage and sulforhodamine 101 had a higher absolute quantum yield (Φ_F=28.5 %), larger excitation–emission gap (Δλ_ex-em=211 nm), and longer emission lifetime (τ=7.0 ns) as compared to the guest (Φ_F=10.5 %; Δλ_ex-em=11 nm; τ=4.9 ns), and purer emission (Δλ_FWHM=38 nm) as compared to the host (Δλ_FWHM=111 nm).     

Photoswitchable Sol–Gel Transitions and Catalysis Mediated by Polymer Networks with Coumarin-Decorated Cu24L24 Metal–Organic Cages as Junctions

Photoresponsive materials that change in response to light have been studied for a range of applications. These materials are often metastable during irradiation, returning to their pre-irradiated state after removal of the light source. Herein, we report a polymer gel comprising poly(ethylene glycol) star polymers linked by Cu₂₄L₂₄ metal–organic cages/polyhedra (MOCs) with coumarin ligands. In the presence of UV light, a photosensitizer, and a hydrogen donor, this “polyMOC” material can be reversibly switched between Cu^II, Cu^I, and Cu⁰. The instability of the MOC junctions in the Cu^I and Cu⁰ states leads to network disassembly, forming Cu^I/Cu⁰ solutions, respectively, that are stable until re-oxidation to Cu^II and supramolecular gelation. This reversible disassembly of the polyMOC network can occur in the presence of a fixed covalent second network generated in situ by copper-catalyzed azide-alkyne cycloaddition (CuAAC), providing interpenetrating supramolecular and covalent networks.     

Dynamic Stereochemistry of M8Pd6 Supramolecular Cages Based on Metal-Center Lability for Differential Chiral Induction,Resolution, and Recognition

A series of isostructural supramolecular cages with a rhombic dodecahedron shape have been assembled with distinct metal-coordination lability (M₈Pd₆-MOC-16, M=Ru²⁺, Fe²⁺, Ni²⁺, Zn²⁺). The chirality transfer between metal centers generally imposes homochirality on individual cages to enable solvent-dependent spontaneous resolution of Δ₈/Λ₈−M₈Pd₆ enantiomers; however, their distinguishable stereochemical dynamics manifests differential chiral phenomena governed by the cage stability following the order Ru₈Pd₆ > Ni₈Pd₆ > Fe₈Pd₆ > Zn₈Pd₆. The highly labile Zn centers endow the Zn₈Pd₆ cage with conformational flexibility and deformation, enabling intrigue chiral-Δ₈/Λ₈−Zn₈Pd₆ to meso-Δ₄Λ₄−Zn₈Pd₆ transition induced by anions. The cage stabilization effect differs from inert Ru²⁺, metastable Fe²⁺/Ni²⁺, and labile Zn²⁺, resulting in different chiral-guest induction. Strikingly, solvent-mediated host–guest interactions have been revealed for Δ₈/Λ₈−(Ru/Ni/Fe)₈Pd₆ cages to discriminate the chiral recognition of the guests with opposite chirality. These results demonstrate a versatile procedure to control the stereochemistry of metal-organic cages based on the dynamic metal centers, thus providing guidance to maneuver cage chirality at a supramolecular level by virtue of the solvent, anion, and guest to benefit practical applications.     

The Redox Coupling Effect in a Photocatalytic RuII-PdII Cage with TTF Guest as Electron Relay Mediator for Visible-Light Hydrogen-Evolving Promotion

A nanocage coupling effect from a redox Ru^II-Pd^II metal–organic cage (MOC-16) is demonstrated for efficient photochemical H₂ 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 relay mediator to improve the overall electron transfer efficiency in the host–guest system in a long-time scale, leading to significant promotion of visible-light driven H₂ 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 H₂ evolution. Such interaction provides an example to understand the interplay between the redox-active nanocage and guest for optimization of redox events and photocatalytic activities in a confined chemical nanoenvironment.     

A novel heterometallic dinuclear compound: rac‐pentaaqua‐1κ5O‐(μ‐2‐sulfidoacetato‐1:2κ3O:O′,S)bis(2‐sulfidoacetato‐2κ2O,S)manganese(II)tin(IV)

The title racemic heterometallic dinuclear compound, [MnSn(C₂H₂O₂S)₃(H₂O)₅], (I), contains one main group Sn^IV metal centre and one transition metal Mn^II centre, and, by design, links the Mn^II centre to the building unit of the (Δ/Λ) [SnL₃]²⁻ complex anion (L is the 2‐sulfidoacetate dianion). In this cluster, the Sn^IV centre of the (Δ/Λ) [SnL₃]²⁻ unit is coordinated by three O atoms and three S atoms from three L ligands to form an [SnO₃S₃] octahedral coordination environment. The Mn^II centre is in an [MnO₆] octahedral coordination environment, with five O atoms from five water molecules and the sixth from the μ₂‐L ligand of the (Δ/Λ) [SnL₃]²⁻ unit. Between adjacent dinuclear molecules, there are many hydrogen‐bond interactions of O—H...O, O—H...S, C—H...O and C—H...S types. Of these, eight pairs of O—H...O hydrogen bonds fuse all the dinuclear molecules into two‐dimensional supramolecular sheets along the bc plane. Adjacent supramolecular sheets are further connected through O—H...S hydrogen bonds to give a three‐dimensional supramolecular network.     

Self-Assembly of Coordination Polyhedra with Highly Entangled Faces Induced by Metal–Acetylene Interactions

The self-assembly of nanostructures is dominated by a limited number of strong coordination elements. Herein, we show that metal–acetylene π-coordination of a tripodal ligand (L) with acetylene spacers gave an M₃L₂ double-propeller motif (M=Cu^I or Ag^I), which dimerized into an M₆L₄ interlocked cage (M=Cu^I). Higher (M₃L₂)_n oligomers were also selectively obtained: an M₁₂L₈ truncated tetrahedron (M=Cu^I) and an M₁₈L₁₂ truncated trigonal prism (M=Ag^I), both of which contain the same double-propeller motif. The higher oligomers exhibit multiply entangled facial structures that are classified as a trefoil knot and a Solomon link. The inner cavities of the structures encapsulate counteranions, revealing a potential new strategy towards the synthesis of functional hollow structures that is powered by molecular entanglements.     

Host–Guest Recognition and Fluorescence of a Tetraphenylethene‐Based Octacationic Cage

We report the synthesis and characterization of a three‐dimensional tetraphenylethene‐based octacationic cage that shows host–guest recognition of polycyclic aromatic hydrocarbons (e.g. coronene) in organic media and water‐soluble dyes (e.g. sulforhodamine 101) in aqueous media through CH???π, π–π, and/or electrostatic interactions. The cage?coronene exhibits a cuboid internal cavity with a size of approximately 17.2×11.0×6.96 ų and a “hamburger”‐type host–guest complex, which is hierarchically stacked into 1D nanotubes and a 3D supramolecular framework. The free cage possesses a similar cavity in the crystalline state. Furthermore, a host–guest complex formed between the octacationic cage and sulforhodamine 101 had a higher absolute quantum yield (Φ_F=28.5 %), larger excitation–emission gap (Δλ_ex‐em=211 nm), and longer emission lifetime (τ=7.0 ns) as compared to the guest (Φ_F=10.5 %; Δλ_ex‐em=11 nm; τ=4.9 ns), and purer emission (Δλ_FWHM=38 nm) as compared to the host (Δλ_FWHM=111 nm).     

Embedding and Positioning of Two FeII4L4 Cages in Supramolecular Tripeptide Gels for Selective Chemical Segregation

An unreported d,l ‐tripeptide self‐assembled into gels that embedded Fe^II₄L₄ metal–organic cages to form materials that were characterized by TEM, EDX, Raman spectroscopy, rheometry, UV/Vis and NMR spectroscopy, and circular dichroism. The cage type and concentration modulated gel viscoelasticity, and thus the diffusion rate of molecular guests through the nanostructured matrix, as gauged by ¹⁹F and ¹H NMR spectroscopy. When two different cages were added to spatially separated gel layers, the gel–cage composite material enabled the spatial segregation of a mixture of guests that diffused into the gel. Each cage selectively encapsulated its preferred guest during diffusion. We thus present a new strategy for using nested supramolecular interactions to enable the separation of small molecules.     

Novel solid-state synthesis of dimeric 4-aryl-1,4-dihydropyridines

On irradiation in the solid state the 4-aryl-1,4-dihydroypridines 1 undergo [2+2] cycloadditon to centrosymmetric head-to-tail dimers 3 and 4a . The almost exclusive formation of the cage dimers 3 via the C₂-symmetric syn-dimers 2 takes place in nearly quantitative yields, in contrast with the cycloaddition reaction of the anti-dimer 4a , which is accompanied by photooxidation to pyridine 5a .     

Anti- and syn-Tricyclo [4.2.1.12,5]decane. Preliminary communication

The two novel tricyclic C₁₀H₁₆ compounds anti- and syn-tricyclo [4.2.1.1^2,5]- decane ( 16 and 17 , respectively) were synthesized starting either from the photodimer 2 (anti) or the two cycloaddition products 8 (anti) and 9 (syn).     

Binuclear trans‐Bis(β‐iminoaryloxy)palladium(II) Complexes Doubly Linked with Pentamethylene Spacers: Structure‐Dependent Flapping Motion and Heterochiral Association Behavior of the Clothespin‐Shaped Molecules

The synthesis, structure, and solution‐state behavior of clothespin‐shaped binuclear trans‐bis(β‐iminoaryloxy)palladium(II) complexes doubly linked with pentamethylene spacers are described. Achiral syn and racemic anti isomers of complexes 1 – 3 were prepared by treating Pd(OAc)₂ with the corresponding N,N′‐bis(β‐hydroxyarylmethylene)‐1,5‐pentanediamine and then subjecting the mixture to chromatographic separation. Optically pure (100 % ee) complexes, (+)‐anti‐ 1 , (+)‐anti‐ 2 , and (+)‐anti‐ 3 , were obtained from the racemic mixture by employing a preparative HPLC system with a chiral column. The trans coordination and clothespin‐shaped structures with syn and anti conformations of these complexes have been unequivocally established by X‐ray diffraction studies. ¹H NMR analysis showed that (±)‐anti‐ 1 , (±)‐anti‐ 2 , syn‐ 2 , and (±)‐anti‐ 3 display a flapping motion by consecutive stacking association/dissociation between cofacial coordination planes in [D₈]toluene, whereas syn‐ 1 and syn‐ 3 are static under the same conditions. The activation parameters for the flapping motion (ΔH^≠ and ΔS^≠) were determined from variable‐temperature NMR analyses as 50.4 kJ mol^?1 and 60.1 J mol^?1 K^?1 for (±)‐anti‐ 1 , 31.0 kJ mol^?1 and ?22.7 J mol^?1 K^?1 for (±)‐anti‐ 2 , 29.6 kJ mol^?1 and ?57.7 J mol^?1 K^?1 for syn‐ 2 , and 35.0 kJ mol^?1 and 0.5 J mol^?1 K^?1 for (±)‐anti‐ 3 , respectively. The molecular structure and kinetic parameters demonstrate that all of the anti complexes flap with a twisting motion in [D₈]toluene, although (±)‐anti‐ 1 bearing dilated Z‐shaped blades moves more dynamically than I‐shaped (±)‐anti‐ 2 or the smaller (±)‐anti‐ 3 . Highly symmetrical syn‐ 2 displays a much more static flapping motion, that is, in a see‐saw‐like manner. In CDCl₃, (±)‐anti‐ 1 exhibits an extraordinary upfield shift of the ¹H NMR signals with increasing concentration, whereas solutions of (+)‐anti‐ 1 and the other syn/anti analogues 2 and 3 exhibit negligible or slight changes in the chemical shifts under the same conditions, which indicates that anti‐ 1 undergoes a specific heterochiral association in the solution state. Equilibrium constants for the dimerizations of (±)‐ and (+)‐anti‐ 1 in CDCl₃ at 293 K were estimated by curve‐fitting analysis of the ¹H NMR chemical shift dependences on concentration as 26 M ^?1 [K_D(racemic)] and 3.2 M ^?1 [K_D(homo)], respectively. The heterochiral association constant [K_D(hetero)] was estimated as 98 M ^?1, based on the relationship K_D(racemic)=1/2 K_D(homo)+1/4 K_D(hetero). An inward stacking motif of interpenetrative dimer association is postulated as the mechanistic rationale for this rare case of heterochiral association.     

Dynamic Open Coordination Cage from Nonsymmetrical Imidazole–Pyridine Ditopic Ligands for Turn‐On/Off Anion Binding

This work demonstrates a new nonconventional ligand design, imidazole/pyridine‐based nonsymmetrical ditopic ligands ( 1 and 1 ^S ), to construct a dynamic open coordination cage from nonsymmetrical building blocks. Upon complex formation with Pd²⁺ at a 1:4 molar ratio, 1 and 1 ^S initially form mononuclear PdL₄ complexes (Pd²⁺( 1 )₄ and Pd²⁺( 1 ^S )₄) without formation of a cage. The PdL₄ complexes undergo a stoichiometrically controlled structural transition to Pd₂L₄ open cages ((Pd²⁺)₂( 1 )₄ and (Pd²⁺)₂( 1 ^S )₄) capable of anion binding, leading to turn‐on anion binding. The structural transitions between the Pd₂L₄ open cage and the PdL₄ complex are reversible. Thus, stoichiometric addition (2 equiv) of free 1 ^S to the (Pd²⁺)₂( 1 ^S )₄ open cage holding a guest anion ((Pd²⁺)₂( 1 ^S )₄?G^?) enables the structural transition to the Pd²⁺( 1 ^S )₄ complex, which does not have a cage and thus causes the release of the guest anion (Pd²⁺( 1 ^S )₄+G^?).     

Syntheses,spectroscopy, optical properties,and diastereoselectivity of copper(II)-complexes with chiral aminoalcohol based Schiff bases

Chiral aminoalcohol based Schiff bases (R or S)-2-{(E)-(2-hydroxy-1-phenylethylimino)methyl}phenol and (R/S)-2-{(E)-(2-hydroxy-2-phenylethylimino)methyl}phenol coordinate to copper(II)acetate to give enantiopure Λ/Δ- or Δ/Λ-bis[(R or S)-2-{(E)-(2-hydroxy-1-phenylethylimino)methyl}phenoxide-κ²N,O]copper(II), {Λ/Δ-Cu(R-L1)₂ (1) or Δ/Λ-Cu(S-L1)₂ (2)}, and racemic Δ/Λ- and Λ/Δ-bis[(R/S)-2-{(E)-(2-hydroxy-2-phenylethylimino)methyl}phenoxide-κ²N,O]copper(II), {Δ/Λ- and Λ/Δ-Cu(R/S-L2)₂ (3)}, respectively. The complexes are characterized by elemental analyzes, IR, UV–Vis, polarimetry, circular dichroism (CD), differential scanning calorimeter (DSC), and mass spectroscopy. Polarimetry shows the rotation to the left at ?113.6° (1) and to the right at +106.4^o (2). CD spectra show the expected mirror-image relationship with opposite sign of ellipticity maxima (Δε_max = +0.43 for 1 and ?0.42 M^?1 dm³ cm^?1 for 2 at 638 nm) due to the d-d transitions of the metal ion. CD spectral analyzes further reveal a diastereoselectivity or diastereomeric excess towards Λ-Cu(R-L1)₂ or Δ-Cu(S-L1)₂ configuration for 1 or 2 in solution. Similarly, the enantiomeric pair of Δ-Cu(R-L2)₂ and Λ-Cu(S-L2)₂ configurations (CD inactive) for 3 will be preferred in solution. Electronic spectra in different solvents reveal a negative solvatochromism by shifting absorption maxima of the MLCT band to higher energies in solvents of increasing polarity as well as acceptor number. DSC analyzes show an endothermic peak at 525.5 (1) or 528.7 K (2), corresponding to a thermally induced structural phase transformation from distorted square-planar to regular tetrahedral.     

Complexation of Ethanol by a Helical Tubuland Diol Host

The cage compound 4,7-dimethylpentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecane-anti-4,anti-7-diol 3 and its 4,7-bis(d ₃-methyl) derivative 4 form 1:1 cocrystalline complexes with ethanol instead of the expected helical tubulate inclusion compounds. The X-ray crystal structure of (4)·(ethanol) [(C₁₃H₁₂D₆O₂)·(C₂H₆O), Cmca, a 19.049(2), b 14.932(2), c 10.117(1) Å, Z 8, R 0.061] shows that the key supramolecular synthon is a hydrogen-bonded (O — H)₆ cycle of hydroxy groups constructed from two ethanols (in ring positions 1 and 4) and four diols. This uncommon centrosymmetric motif permits efficient lattice packing of ethanol and both diol enantiomers into layers without requiring the self-resolution that would be mandatory in forming the helical tubulate structure.     

Anti to syn isomerization of oxacalix[4]arene bearing two methyl groups at the intra-annular distal positions

The thermal isomerization of anti to syn stereoisomers of oxacalix[4]arene bearing two methyl groups at the intra-annular distal positions was investigated by temperature-dependent NMR spectroscopy. The conversion followed a first-order kinetics, and very slowly proceeded at 473 K in nitrobenzene-d₅ with a half-life of 7.2 h. The free energy of activation (ΔG^≠ 139 kJ mol⁻¹) is much higher than those for the ring inversion of related calix[4]arene derivatives.     

Improved Acid Resistance of a Metal–Organic Cage Enables Cargo Release and Exchange between Hosts

The use of di(2-pyridyl)ketone in subcomponent self-assembly is introduced. When combined with a flexible triamine and zinc bis(trifluoromethanesulfonyl)imide, this ketone formed a new Zn₄L₄ tetrahedron 1 bearing twelve uncoordinated pyridyl units around its metal-ion vertices. The acid stability of 1 was found to be greater than that of the analogous tetrahedron 2 built from 2-formylpyridine. Intriguingly, the peripheral presence of additional pyridine rings in 1 resulted in distinct guest binding behavior from that of 2 , affecting guest scope as well as binding affinities. The different stabilities and guest affinities of capsules 1 and 2 enabled the design of systems whereby different cargoes could be moved between cages using acid and base as chemical stimuli.     

Asymmetric 1,3‐Dipolar Cycloadditions of 2‐Diazocyclohexane‐1,3‐diones and Alkyl Diazopyruvates

The 1,3‐dipolar cycloaddition reactions of 2‐diazocyclohexane‐1,3‐dione ( 7a ; Table 1) and of alkyl diazopyruvates ( 11a – e ; Table 3) to 2,3‐dihydrofuran and other enol ethers have been investigated in the presence of chiral transition metal catalysts. With Rh^II catalysts, the cycloadditions were not enantioselective, but those catalyzed by [Ru^IICl₂( 1a )] and [Ru^IICl₂( 1b )] proceeded with enantioselectivities of up to 58% and 74% ee, respectively, when diazopyruvates 11 were used as substrates. The phenyliodonium ylide 7c yielded the adduct 8a in lower yield and poorer selectivity than the corresponding diazo precursor 7a (Table 2) upon decomposition with [Ru(pybox)] catalysts. This suggests that ylide decomposition by Ru^II catalysts, contrary to that of the corresponding diazo precursors, does not lead to Ru‐carbene complexes as reactive intermediates. Our method represents the first reproducible, enantioselective 1,3‐cycloaddition of these types of substrates.     

Transport,Electrochemical and Thermophysical Properties of Two N‐Donor‐Functionalised Ionic Liquids

Two N‐donor‐functionalised ionic liquids (ILs), 1‐ethyl‐1,4‐dimethylpiperazinium bis(trifluoromethylsulfonyl)amide ( 1 ) and 1‐(2‐dimethylaminoethyl)‐dimethylethylammonium bis(trifluoromethylsulfonyl)amide ( 2 ), were synthesised and their electrochemical and transport properties measured. The data were compared with the benchmark system, N‐butyl‐N‐methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ( 3 ). Marked differences in thermal and electrochemical stability were observed between the two tertiary‐amine‐functionalised salts and the non‐functionalised benchmark. The former are up to 170 K and 2 V less stable than the structural counterpart lacking a tertiary amine function. The ion self‐diffusion coefficients (D_i) and molar conductivities (Λ) are higher for the IL with an open‐chain cation ( 2 ) than that with a cyclic cation ( 1 ), but less than that with a non‐functionalised, heterocyclic cation ( 3 ). The viscosities (η) show the opposite behaviour. The Walden [Λ∝(1/η)^t] and Stokes–Einstein [D_i/T)∝(1/η)^t] exponents, t, are very similar for the three salts, 0.93–0.98 (±0.05); that is, the self‐diffusion coefficients and conductivity are set by η. The D_i for 1 and 2 are the same, within experimental error, at the same viscosity, whereas Λ for 1 is approximately 13 % higher than that of 2 . The diffusion and molar conductivity data are consistent, with a slope of 0.98±0.05 for a plot of ln(ΛT) against ln(D₊+D_?). The Nernst–Einstein deviation parameters (Δ) are such that the mean of the two like‐ion VCCs is greater than that of the unlike ions. The values of Δ are 0.31, 0.36 and 0.42 for 3 , 1 and 2 , respectively, as is typical for ILs, but there is some subtlety in the ion interactions given 2 has the largest value. The distinct diffusion coefficients (DDC) follow the order ${D{{{\rm d}\hfill \atop - - \hfill}}}$ <${D{{{\rm d}\hfill \atop ++\hfill}}}$ <${D{{{\rm d}\hfill \atop +- \hfill}}}$ , as is common for [Tf₂N]^? salts. The ion motions are not correlated as in an electrolyte solution: instead, there is greater anti‐correlation between the velocities of a given anion and the overall ensemble of anions in comparison to those for the cationic analogue, the anti‐correlation for the velocities of which is in turn greater than that for a given ion and the ensemble of oppositely charged ions, an observation that is due to the requirement for the conservation of momentum in the system. The DDC also show fractional SE behaviour with t～0.95.     

Supramolecular-induced regiocontrol over the photochemical [4 + 4] cyclodimerization of NHC- or azole-substituted anthracenes

Thanks to the impressive control that microenvironments within enzymes can have over substrates, many biological reactions occur with high regio- and stereoselectivity. However, comparable regio- and stereoselectivity is extremely difficult to achieve for many types of reactions, particularly photochemical cycloaddition reactions in homogeneous solutions. Here, we describe a supramolecular templating strategy that enables photochemical [4 + 4] cycloaddition of 2,6-difunctionalized anthracenes with unique regio- and stereoselectivity and reactivity using a concept known as the supramolecular approach. The reaction of 2,6-azolium substituted anthracenes H₄-L(PF₆)₂ (L = 1a–1c) with Ag₂O yielded complexes anti-[Ag₂L₂](PF₆)₄ featuring an antiparallel orientation of the anthracene groups. Irradiation of complexes anti-[Ag₂L₂](PF₆)₄ proceeded under [4 + 4] cycloaddition linking the two anthracene moieties to give cyclodimers anti-[Ag₂(2)](PF₆)₂. Reaction of 2,6-azole substituted anthracenes with a dinuclear complex [Cl-Au-NHC–NHC-Au-Cl] yields tetranuclear assemblies with the anthracene moieties oriented in syn-fashion. Irradiation and demetallation gives a [4 + 4] syn-photodimer of two anthracenes. The stereoselectivity of the [4 + 4] cycloaddition between two anthracene moieties is determined by their orientation in the metallosupramolecular assemblies.

A supramolecular templating strategy that enables the photochemical [4 + 4] cycloaddition of 2,6-difunctionalized anthracene derivatives with unique stereoselectivity has been developed based on metal-NHC units.