Polyaromatic nanocapsules as photoresponsive hosts in water

Visible Light [2 + 2] Cycloadditions of Thermoresponsive Dendronized Styryltriazines To Exhibit Tunable Microconfinement

Visible light-triggered photochemical reactions in aqueous media are highly valuable to tailor molecular structures and properties in an ecofriendly manner. Here we report visible light-induced catalyst-free [2 + 2] cycloadditions of thermoresponsive dendronized styryltriazines, which show tunable microconfinement to guest dyes in aqueous media. These dendronized styryltriazines are constituted of conjugated mono- or tristyryltriazines, which carry hydrophilic dendritic oligoethylene glycol (OEG) pendants. They underwent efficient [2 + 2] cycloadditions to form dendronized cyclobutane dimers or oligomers in water through irradiation with visible light of 400 nm, and their cycloaddition behavior was dominated by dendritic architectures and solvent conditions. Dendronization with dendritic OEGs also afforded them characteristic thermoresponsive properties with tunable phase transition temperatures in the range 36-65 °C, which can be further modulated through photocycloaddition of styryltriazine chromophores. Importantly, dendronized styryltriazines can form tunable microenvironments in aqueous media, which encapsulate hydrophobic solvatochromic Nile red to exhibit variable photophysical properties. The encapsulated guest dye can be simultaneously released through noninvasive visible light-induced [2 + 2] cycloaddition reactions.

Double-Wavelength-Switchable Molecular Self-Assembly of a Photoacid and Spirooxazine in an Aqueous Solution

Quadruple-switchable nanoscale assemblies are built by combining two types of water-soluble molecular photoswitches through dipole-dipole interaction. Uniting the wavelength-specific proton dissociation of a photoacid and ring-opening of an anionic spirooxazine results in an assembly that can be addressed by irradiation with two different wavelengths: pH and darkness.

Rigidification-Induced Emissive Metal-Carbene Complexes for Artificial Light Harvesting

A tetraphenylethylene (TPE)-based flexible imidazolium (L) salt was used to develop a di-nuclear silver(I)-tetracarbene (1) complex. Coordination-induced rigidity upon formation of 1 exhibited a 6-fold increase in emission intensity in acetonitrile compared to starting L. Despite TPE being a well-known aggregation-induced emissive moiety, Ag^I-N-heterocyclic carbene (NHC) complex 1 had a remarkably higher fluorescence emission (4-fold) in dilute solution when compared with L in its aggregated state. Finally, this enhanced emission was used to institute a new platform for an artificial light-harvesting system. 1 acted as an energy donor and efficiently transferred energy to Eosin Y (ESY) with a high saturation at a 67:1 (1/ESY) molar ratio. Use of rigidification-induced emission of the Ag^I-NHC complex to fabricate a light-harvesting scaffold is a new approach and can greatly impact the generation of smart materials.

Photocatalysis in Water-Soluble Supramolecular Metal Organic Complex

As an emerging subset of organic complexes, metal complexes have garnered considerable attention owing to their outstanding structures, properties, and applications. In this content, metal-organic cages (MOCs) with defined shapes and sizes provide internal spaces to isolate water for guest molecules, which can be selectively captured, isolated, and released to achieve control over chemical reactions. Complex supramolecules are constructed by simulating the self-assembly behavior of the molecules or structures in nature. For this purpose, massive amounts of cavity-containing supramolecules, such as metal-organic cages (MOCs), have been extensively explored for a large variety of reactions with a high degree of reactivity and selectivity. Because sunlight and water are necessary for the process of photosynthesis, water-soluble metal-organic cages (WSMOCs) are ideal platforms for photo-responsive stimulation and photo-mediated transformation by simulating photosynthesis due to their defined sizes, shapes, and high modularization of metal centers and ligands. Therefore, the design and synthesis of WSMOCs with uncommon geometries embedded with functional building units is of immense importance for artificial photo-responsive stimulation and photo-mediated transformation. In this review, we introduce the general synthetic strategies of WSMOCs and their applications in this sparking field.

Mechanochemical Activation of Anthracene [4+4] Cycloadducts

Controlled formation and breaking of weak chemical bonds is a versatile method for modifying the properties of materials. Anthracene [4+4] cycloadducts are a prime example that can be formed by light and opened by external forces. We address the theoretical description of mechanochemistry of these cycloadducts, where the standard constraint geometry simulates forces approach fails due to the lack of consideration of temperature. Explicit inclusion of external forces reveals the corresponding transition barriers that are clearly dominated by rupture of the [4+4] inter-anthracene bonds. Other bonds come into play at extremely large forces only, which cannot be expected to be reached under ambient conditions. The theoretical results are in line with the experimental rheology of [4+4]-linked anthracene polymers, which indicates reversible re-formation of [4+4] cycloaddition bonds with ultraviolet light after mechanochemical bond breaking due to applied shear stress.

Aromatic micelles: toward a third-generation of micelles

Micelles are useful and widely applied molecular assemblies, formed from amphiphilic molecules, in water. The majority of amphiphiles possess an alkyl chain as the hydrophobic part. Amphiphiles bearing hydrophilic and hydrophobic polymer chains generate so-called polymeric micelles in water. This review focuses on the recent progress of "aromatic micelles", formed from bent polyaromatic/aromatic amphiphiles, for the development of third-generation micelles. Thanks to multiple host-guest interactions, e.g., the hydrophobic effect and π-π/CH-π interactions, the present micelles display wide-ranging uptake abilities toward various hydrophobic compounds in water. In addition to such host functions, new stimuli-responsive aromatic micelles with pH, light, and redox switches, aromatic oligomer micelles, saccharide-coated aromatic micelles, and related cycloalkane-based micelles were recently developed by our group.

Morpholine-Functionalized Multicomponent Metallacage as a Vector for Lysosome-Targeted Cell Imaging

Metallacages with suitable cavities and specific functions are promising delivery vectors in biological systems. Herein, we report a morpholine-functionalized metallacage for lysosome-targeted cell imaging. The efficient host-guest interactions between the metallacage and dyes prevent them from aggregation, so their emission in aqueous solutions is well maintained. The fluorescence quantum yield of these host-guest complexes reaches 74.40%. Therefore, the metallacage is further employed as a vector to deliver dyes with different emission colors (blue, green, and red) into lysosomes for targeted imaging. This research affords a type of vector for the delivery of various cargos toward biological applications, which will enrich the usage of metallacages in biomedical engineering.

Switchable bifunctional molecular recognition in water using a pH-responsive Endo-functionalized cavity

The construction of water-soluble synthetic hosts with a stimuli-responsive endo-functionalized cavity is challenging. These hosts feature a switchable cavity and may bring new properties to the fields of self-assembly, molecular machines, and biomedical sciences. Herein, we report a pair of water-soluble naphthotubes with a pH-responsive endo-functionalized cavity. The inward-directing secondary amine group of the hosts can be protonated and deprotonated. Thus, the hosts have different cavity features at the two states and show drastically different binding preference and selectivity in water. We reveal that the binding difference of the two host states is originated from the differences in charge repulsion, hydrogen bonding and the hydrophobic effects. Moreover, the guest binding can be easily switched in a ternary mixture with two guest molecules by adjusting the pH value of the solution. These pH-responsive hosts may be used for the construction of smart self-assembly systems and water-soluble molecular machines.

Entropy Versus Enthalpy Controlled Temperature/Redox Dual-Triggered Cages for Selective Anion Encapsulation and Release

New C₃ -symmetric imidazole ligands were designed with phosphine and phosphine oxide linkers (L^P and L^PO , respectively) to demonstrate a dual-triggered dynamic closed coordination cage. Both L^P and L^PO form discrete Zn₄ L₄ -closed cages (1^P and 1^PO , respectively) with excellent selectively for BPh₄ ^- , whereas 1^P and 1^PO encapsulate neither a slightly larger size anion [B(C₆ H₄ CH₃ )₄ ^- ] nor smaller size anions (BF₄ ^- , PF₆ ^- , SbF₆ ^- , and OSO₂ CF₃ ^- ). 1^PO exhibits more negative enthalpy and entropy changes upon anion encapsulation, thus releasing almost all of the encapsulated anions at high temperature (343 K) (trigger 1: BPh₄ ^- ⊂1^PO ← → 1^PO +BPh₄ ^- ). In contrast 1^P has less negative enthalpy and entropy changes, thus preserving the captured anion over a wide range of temperatures (298 K to 343 K). The 1^P cage can be quantitatively oxidized to the 1^PO cage by a mild oxidant (Ox.=H₂ O₂ ), and therefore the captured anion can be released by a redox triggering event (trigger 2: BPh₄ ^- ⊂1^P +Ox.→1^PO +BPh₄ ^- ).

Hydrogen-Bonded Dimeric Capsules with Appended Spiropyran Units: Towards Controlled Cargo Release

We report the synthesis of unprecedented tetra-urea derivatives of calix[4]arene and calix[4]pyrrole containing four spiropyran (SP) units at their upper rim. We investigate the photo- and acid-induced isomerization of the monomeric and homo-dimeric tetra-ureas derivatives using UV-Vis and ¹ H NMR spectroscopies. At micromolar concentration, irradiation of the samples with 365 nm light induces changes in their absorption spectra that are consistent with SP→merocyanine (MC) isomerization. However, analogous experiments at millimolar concentration do not produce noticeable changes in the ¹ H NMR spectra. The addition of triflic acid to micromolar and millimolar solutions of the tetra-ureas produces the quantitative isomerization of the SP units to the protonated merocyanine form (E-MCH⁺ ) and the simultaneous disassembly of the capsular dimers to form ill-defined aggregates. The neutralization of the acid solutions resets the SP form. Under these acid/base treatment conditions, the controlled release of the included guest and the reassembly of the all-SP tetra-urea dimers occurs at different extents depending on its calix[4]arene or calix[4]pyrrole scaffold.

Supramolecular Singlet Fission of Pentacene Dimers within Polyaromatic Capsules

We herein report a new set of supramolecular nanotools for the generation and modulation of singlet fission (SF) of noncovalent/covalent pentacene dimers. Two molecules of a pentacene monomer with bulky substituents are facilely encapsulated by a polyaromatic capsule, composed of naphthalene-based bent amphiphiles, in water. The encapsulated noncovalent dimer converts to otherwise undetectable triplet pairs and an individual triplet in high quantum yields (179% and 53%, respectively) even under high dilution conditions. Within the capsule, a covalently linked pentacene dimer with bulky groups generates two triplet pair intermediates in parallel, which are hardly distinguished in bulk solution, in excellent total quantum yield (196%). The yield of the individual triplet is enhanced by 1.6 times upon encapsulation. For both types of pentacene dimers, the SF features can be readily tuned by changing the polyaromatic panels of the capsule (i.e., anthracene and phenanthrene).

Nanoformulations of Coumarins and the Hybrid Molecules of Coumarins with Potential Anticancer Effects

Coumarins are the secondary metabolites of some plants, fungi, and bacteria. Coumarins and the hybrid molecules of coumarins are the compounds which have been widely studied for their potential anticancer effects. They belong to benzopyrone chemical class, more precisely benzo-α-pyrones, where benzene ring is fused to pyrone ring. In nature, coumarins are found in higher plants like Rutaceae and Umbelliferae and some essential oils like cinnamon bark oil, cassia leaf oil and lavender oil are also rich in coumarins. The six main classes of coumarins are furanocoumarins, dihydrofuranocoumarins, pyrano coumarins, pyrone substituted coumarins, phenylcoumarins and bicoumarins. As well as their wide range of biological activities, coumarins and the hybrid molecules of coumarins are proven to have an important role in anticancer drug development due to the fact that many of its derivatives have shown an anticancer activity on various cell lines. Osthol, imperatorin, esculetin, scopoletin, umbelliprenin, angelicine, bergamottin, limettin, metoxhalen, aurapten and isopimpinellin are some of these coumarins. This review summarizes the anticancer effects of coumarins and their hybrid molecules including the novel pharmaceutical formulations adding further information on the topic for the last ten years and basically focusing on the structureactivity relationship of these compounds in cancer.

An Aromatic Micelle-Based Saccharide Cluster with Changeable Fluorescent Color and its Protein Interactions

To develop a new type of synthetic saccharide clusters with changeable fluorescent colors, we herein designed a multisaccharide-coated aromatic micelle. The new cluster forms in water through the quantitative assembly of bent polyaromatic amphiphiles bearing three mannose groups. The spherical assembly, with a 2 nm-sized polyaromatic core and ca. 18 saccharide pendants, is stable even under high dilution conditions (up to 0.02 mM). The emission intensity and color of the saccharide cluster can be altered from moderate blue (Φ_F =19 %) to strong red, orange, and green (Φ_F up to 67 %) upon encapsulation of hydrophobic fluorescent dyes in water. Moreover, the present fluorescent clusters, both with and without the dyes, display selective interactions with mannose-binding proteins in vitro.

Phase-Dependent Reactivity and Host-Guest Behaviors of a Metallo-Macrocycle in Liquid and Solid-State Photosensitized Oxygenation Reactions

The photochemical oxygenation reactions of a host-guest complex, pCp⊂[Ag₂L0](SbF₆)₂ (pCp = [2.2]paracyclophane) have been investigated in solution and in the solid state, using the macrocyclic ligand L0 having four anthracene moieties in the framework. As a result, it was found that the reactivity and host-guest functions show remarkable phase dependence. In solution, the photosensitized oxygenation of all the anthracene moieties of L0 resulted in a fully oxygenated macrocycle [Ag₂L4](SbF₆)₂ as the final product, while simultaneously the guest molecule was dissociated from the macrocyclic cavity. On the other hand, in an amorphous solid of pCp⊂[Ag₂L0](SbF₆)₂ prepared by decomposing single crystals through the removal of the crystalline solvent, the oxygenated site of L0 was significantly controlled to provide a site-selectively oxygenated inclusion complex, pCp⊂[Ag₂L1](SbF₆)₂, possessing a mono-oxygenated C_s-symmetrical macrocyclic skeleton.

Self-assembled metallasupramolecular cages towards light harvesting systems for oxidative cyclization

Designing artificial light harvesting systems with the ability to utilize the output energy for fruitful application in aqueous medium is an intriguing topic for the development of clean and sustainable energy. We report here facile synthesis of three prismatic molecular cages as imminent supramolecular optoelectronic materials via two-component coordination-driven self-assembly of a new tetra-imidazole donor (L) in combination with 180°/120° di-platinum(ii) acceptors. Self-assembly of 180° trans-Pt(ii) acceptors A1 and A2 with L leads to the formation of cages Pt4 L 2(1a) and Pt8 L 2(2a) respectively, while 120°-Pt(ii) acceptor A3 with L gives the Pt8 L 2(3a) metallacage. PF6 - analogues (1b, 2b and 3b) of the metallacages possess a high molar extinction coefficient and large Stokes shift. 1b-3b are weakly emissive in dilute solution but showed aggregation induced emission (AIE) in a water/MeCN mixture as well as in the solid state. AIE active 2b and 3b in aqueous (90% water/MeCN mixture) medium act as donors for fabricating artificial light harvesting systems via Förster resonance energy transfer (FRET) with organic dye rhodamine-B (RhB) with high energy efficiency and good antenna effect. The metallacages 2b and 3b represent an interesting platform to fabricate new generation supramolecular aqueous light harvesting systems with high antenna effect. Finally, the harvested energy of the LHSs (2b + RhB) and (3b + RhB) was utilized successfully for efficient visible light induced photo-oxidative cross coupling cyclization of N,N-dimethylaniline (4) with a series of N-alkyl/aryl maleimides (5) in aqueous acetonitrile with dramatic enhancement in yields compared to the reactions with RhB or cages alone.

Synthesis of Anthracene-Based Cyclic π-Clusters and Elucidation of their Properties Originating from Congested Aromatic Planes

Synthesis and properties of anthracene-based cyclic π-clusters which possess two and four anthracene units are discussed. The optimal cyclization conditions were determined based on a nickel(0)-mediated reaction that afforded a cyclic anthracene dimer as the major product. Bringing two anthracene planes in close proximity in a face-to-face manner resulted in red-shifted absorption owing to the narrowing of the HOMO-LUMO gap. The cyclic anthracene dimer exhibits multi-stimuli responsiveness due to high π-congestion. For example, photoirradiation on the anthracene dimer affords its photoisomer having C-C bonds that are longer than 1.65 Å, which can undergo thermal reversion under gentle heating. This enabled mechanochromism of the photoisomer (colorless) to the original anthracene dimer (red). Photoisomerization was also observed in the crystalline state, accompanied by crystal jumping or collapsing, that is, the photosalient effect.

Three host peculiarities of a cycloalkane-based micelle toward large metal-complex guests

Linear alkanes are essential building blocks for natural and artificial assemblies in water. As compared with typical, linear alkane-based micelles and recent aromatic micelles, we herein develop a cycloalkane-based micelle, consisting of bent amphiphiles with two cyclohexyl frameworks. This uncommon type of micelle, with a spherical core diameter of ~ 2 nm, forms in water in a spontaneous and quantitative manner. The cycloalkane-based, hydrophobic cavity displays peculiar host abilities as follows: (i) highly efficient uptake of sterically demanding Zn(II)-tetraphenylporphyrin and rubrene dyes, (ii) selective uptake of substituted Cu(II)-phthalocyanines and spherical nanocarbons, and (iii) uptake-induced solution-state emission of [Au(I)-dimethylpyrazolate]₃ in water. These host functions toward the large metal-complex and other guests studied herein remain unaccomplished by previously reported micelles and supramolecular containers.

Typical micelles are molecular assemblies composed of amphiphiles bearing linear alkyl chains. Herein, the authors present an uncommon type of cycloalkane-based bent amphiphile and its micelle which encapsulates large metal- complexes with high uptake efficiency, selectivity, and emissivity in water.

An aromatic micelle with bent pentacene-based panels: encapsulation of perylene bisimide dyes and graphene nanosheets

We herein report the quantitative formation of a new aromatic micelle from bent pentacene-based amphiphiles in water. Upon encapsulation, perylene bisimide dyes form a parallel stacked dimer and graphene nanosheets comprise few layer sheets with small lateral size.

For exploitation of a new class of aromatic micelles, we synthesized a bent pentacene-based amphiphilic molecule through Diels–Alder reaction. The amphiphiles bearing two trimethylammonium tethers assemble into a spherical aromatic micelle, with an average core diameter of 1.5 nm, in water at room temperature. The new aromatic micelle efficiently encapsulates perylene bisimide (PBI) dyes and graphene nanosheets (GNS) in water. The encapsulated PBI dyes form a parallel stacked dimer, exhibiting characteristic absorption and emission bands. In addition, the encapsulated GNS are composed of few-layer graphene sheets with an average lateral size of ∼7 nm, as confirmed by Raman spectroscopy. The resultant, aqueous host–guest complexes are stable even after three weeks in water under ambient conditions.

Controlled binding of organic guests by stimuli-responsive macrocycles

Synthetic supramolecular chemistry pursues not only the construction of new matter, but also control over its inherently dynamic behaviour.

Selective Separation of Polyaromatic Hydrocarbons by Phase Transfer of Coordination Cages

Here we report a new supramolecular strategy for the selective separation of specific polycyclic aromatic hydrocarbons (PAHs) from mixtures. The use of a triethylene glycol-functionalized formylpyridine subcomponent allowed the construction of an Fe^II₄L₄ tetrahedron 1 that was capable of transferring between water and nitromethane layers, driven by anion metathesis. Cage 1 selectively encapsulated coronene from among a mixture of eight different types of PAHs in nitromethane, bringing it into a new nitromethane phase by transiting through an intermediate water phase. The bound coronene was released from 1 upon addition of benzene, and both the cage and the purified coronene could be separated via further phase separation.

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 Pd₂ L₄ 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 Pd₂ L₄ 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^- ).

Photolysis of a calixpyridinium-based supramolecular amphiphilic assembly and its selective turn-on fluorescence recognition of lysine in water

A new calixpyridinium-based light-responsive host-guest recognition motif was found in this work. This host-guest recognition motif was further discovered to be applied as a selective turn-on fluorescent sensor for lysine over other natural amino acids.

Photoswitchable Förster resonance energy transfer (FRET) within a heterometallic Ir-Pt macrocycle

A new heterometallic macrocycle with photochromic properties was succesfully constructed through coordination-driven self-assembly, which features interesting photoswitchable Förster resonance energy transfer (FRET) behaviour.

Bent Anthracene Dimers as Versatile Building Blocks for Supramolecular Capsules

This Account provides a comprehensive summary of our 1-decade-long investigations into bent anthracene dimers as versatile building blocks for supramolecular capsules. The investigations initiated in 2008 with the design of an anthracene dimer with a meta-phenylene spacer bearing two substituents on the convex side. Using the bent polyaromatic building block, we began to develop novel supramolecular capsules from two different synthetic approaches. One is a coordination approach, which was pursued by converting the building block into a bent ligand with two pyridine units at the terminal positions. The ligands quantitatively assemble into an M₂L₄-type capsule through coordination bonding with metal ions. The other is a π-stacking approach, which was followed by utilizing the block as a bent amphiphilic molecule with two trimethylammonium groups at the spacer. In water, the amphiphiles spontaneously assemble into a micelle-type capsule through the hydrophobic effect and π-stacking interactions. Simple modification of the building block allowed us to prepare a wide variety of coordination capsules as well as π-stacking capsules, bearing different hydrophilic side-chains, terminal substitutions, connecting units, polyaromatic panels, or spacer units. The coordination capsule possesses a rigid cavity, with a diameter of ∼1 nm, surrounded by multiple anthracene panels. The spherical polyaromatic cavity binds various synthetic molecules (e.g., paracyclophanes, corannulene, BODIPY, and fullerene C₆₀) in aqueous solutions. With the aid of the polyaromatic shell, photochemically and thermally reactive radical initiators and oligosulfurs are greatly stabilized in the cavity. Biomolecules such as hydrophilic sucrose and oligo(lactic acid)s as well as hydrophobic androgenic hormones are bound by the capsule with high selectivity. In addition, long amphiphilic poly(ethylene oxide)s are threaded into the closed shell of the capsule(s) to generate unusual pseudorotaxane-shaped host-guest complexes in water. In contrast, the π-stacking capsule furnishes a flexible cavity, adaptable to the size and shape of guest molecules, encircled by multiple anthracene panels. In water, the capsule binds hydrophobic fluorescent dyes (e.g., Nile red and DCM) in the cavity. Simple grinding of the bent amphiphile with highly hydrophobic nanocarbons such as fullerenes, nanographenes, and carbon nanotubes (followed by sonication) as well as metal-complexes such as Cu(II)-phthalocyanines and Mn(III)-tetraphenylporphyrins leads to the efficient formation of water-soluble host-guest complexes upon encapsulation. Red emission from otherwise water-deactivated Eu(III)-complexes is largely enhanced in water through encapsulation. Moreover, the incorporation of pH- and photoswitches into the amphiphile affords stimuli-responsive π-stacking capsules, capable of releasing bound guests by the addition of acid and light irradiation, respectively, in water. The host functions of the coordination and π-stacking capsules are complementary to each other, which enables selection of the capsule-type depending on the envisioned target. We are convinced that continued investigation of the present supramolecular capsules featuring the bent anthracene dimer and its derivatives will further increase their value as advanced molecular tools for synthetic, analytical, material, biological, and/or medical applications.

Light triggered encapsulation and release of C60 with a photoswitchable TPE-based supramolecular tweezers

Stimuli responsive hosts for C₆₀ can control its binding and release on demand. A photoswitchable TPE based supramolecular host can encapsulate C₆₀ in the Z-form with a markedly different visual change in the colour. In addition, the Z-1 bound C₆₀ has been characterized by various spectroscopic methods and mass spectrometry. Upon exposure to visible light (>490 nm), the host switches to the E-form where the structural complementarity with the guest is destroyed as a result of which the C₆₀ is disassembled from the host. The results described herein reveals an actionable roadmap to pursue further advances in component self-assembly particularly light-induced association and dissociation of a guest molecule.