Boosting purely organic room-temperature phosphorescence performance through a host–guest strategy

The host–guest doping system has aroused great attention due to its promising advantage in stimulating bright and persistent room-temperature phosphorescence (RTP). Currently, exploration of the explicit structure–property relationship of bicomponent systems has encountered obstacles. In this work, two sets of heterocyclic isomers showing promising RTP emissions in the solid state were designed and synthesized. By encapsulating these phosphors into a robust phosphorus-containing host, several host–guest cocrystalline systems were further developed, achieving highly efficient RTP performance with a phosphorescence quantum efficiency (ϕ_P) of ∼26% and lifetime (τ_P) of ∼32 ms. Detailed photophysical characterization and molecular dynamics (MD) simulation were conducted to reveal the structure–property relationships in such bicomponent systems. It was verified that other than restricting the molecular configuration, the host matrix could also dilute the guest to avoid concentration quenching and provide an external heavy atom effect for the population of triplet excitons, thus boosting the RTP performance of the guest.

Several host–guest cocrystal systems with bright and persistent room-temperature phosphorescence were developed by utilizing a phosphorus-containing material as a robust host and newly developed isomeric organic phosphors as guests.     

Chiroptical Sensing of Amino Acid Derivatives by Host–Guest Complexation with Cyclo[6]aramide

A hydrogen-bonded (H-bonded) amide macrocycle was found to serve as an effective component in the host–guest assembly for a supramolecular chirality transfer process. Circular dichroism (CD) spectroscopy studies showed that the near-planar macrocycle could produce a CD response when combined with three of the twelve L-α-amino acid esters (all cryptochiral molecules) tested as possible guests. The host–guest complexation between the macrocycle and cationic guests was explored using NMR, revealing the presence of a strong affinity involving the multi-point recognition of guests. This was further corroborated by density functional theory (DFT) calculations. The present work proposes a new strategy for amplifying the CD signals of cryptochiral molecules by means of H-bonded macrocycle-based host–guest association, and is expected to be useful in designing supramolecular chiroptical sensing materials.     

Elucidating dissociation activation energies in host–guest assemblies featuring fast exchange dynamics

The ability to mediate the kinetic properties and dissociation activation energies (E_a) of bound guests by controlling the characteristics of “supramolecular lids” in host–guest molecular systems is essential for both their design and performance. While the synthesis of such systems is well advanced, the experimental quantification of their kinetic parameters, particularly in systems experiencing fast association and dissociation dynamics, has been very difficult or impossible with the established methods at hand. Here, we demonstrate the utility of the NMR-based guest exchange saturation transfer (GEST) approach for quantifying the dissociation exchange rates (k_out) and activation energy (E_a,out) in host–guest systems featuring fast dissociation dynamics. Our assessment of the effect of different monovalent cations on the extracted E_a,out in cucurbit[7]uril:guest systems with very fast k_out highlights their role as “supramolecular lids” in mediating a guest''s dissociation E_a. We envision that GEST could be further extended to study kinetic parameters in other supramolecular systems characterized by fast kinetic properties and to design novel switchable host–guest assemblies.

GEST-NMR is utilized for quantifying the dissociation activation energy (E_a,out) in host-guest systems featuring fast dissociation dynamics.     

Backbonding contributions to small molecule chemisorption in a metal–organic framework with open copper(i) centers

Metal–organic frameworks are promising materials for applications such as gas capture, separation, and storage, due to their ability to selectively adsorb small molecules. The metal–organic framework Cu^I-MFU-4l, which contains coordinatively unsaturated copper(i) centers, can engage in backbonding interactions with various small molecule guests, motivating the design of frameworks that engage in backbonding and other electronic interactions for highly efficient and selective adsorption. Here, we examine several gases expected to bind to the open copper(i) sites in Cu^I-MFU-4l via different electronic interactions, including σ-donation, π-backbonding, and formal electron transfer. We show that in situ Cu L-edge near edge X-ray absorption fine structure (NEXAFS) spectroscopy can elucidate π-backbonding by directly probing excitations to unoccupied backbonding orbitals with Cu d-character, even for gases that participate in other dominant interactions, such as ligand-to-metal σ-donation. First-principles calculations based on density functional theory and time-dependent density functional theory additionally reveal the backbonding molecular orbitals associated with these spectroscopic transitions. The energies of the transitions correlate with the energy levels of the isolated small molecule adsorbates, and the transition intensities are proportional to the binding energies of the guest molecules within Cu^I-MFU-4l. By elucidating the molecular and electronic structure origins of backbonding interactions between electron rich metal centers in metal–organic frameworks and small molecule guests, it is possible to develop guidelines for further molecular-level design of solid-state adsorbents for energy-efficient separations of relevance to industry.

In situ near edge X-ray absorption fine structure spectroscopy directly probes unoccupied states associated with backbonding interactions between the open metal site in a metal–organic framework and various small molecule guests.     

Reconstructing reactivity in dynamic host–guest systems at atomistic resolution: amide hydrolysis under confinement in the cavity of a coordination cage

Spatial confinement is widely employed by nature to attain unique efficiency in controlling chemical reactions. Notable examples are enzymes, which selectively bind reactants and exquisitely regulate their conversion into products. In an attempt to mimic natural catalytic systems, supramolecular metal–organic cages capable of encapsulating guests in their cavity and of controlling/accelerating chemical reactions under confinement are attracting increasing interest. However, the complex nature of these systems, where reactants/products continuously exchange in-and-out of the host, makes it often difficult to elucidate the factors controlling the reactivity in dynamic regimes. As a case study, here we focus on a coordination cage that can encapsulate amide guests and enhance their hydrolysis by favoring their mechanical twisting towards reactive molecular configurations under confinement. We designed an advanced multiscale simulation approach that allows us to reconstruct the reactivity in such host–guest systems in dynamic regimes. In this way, we can characterize amide encapsulation/expulsion in/out of the cage cavity (thermodynamics and kinetics), coupling such host–guest dynamic equilibrium with characteristic hydrolysis reaction constants. All computed kinetic/thermodynamic data are then combined, obtaining a statistical estimation of reaction acceleration in the host–guest system that is found in optimal agreement with the available experimental trends. This shows how, to understand the key factors controlling accelerations/variations in the reaction under confinement, it is necessary to take into account all dynamic processes that occur as intimately entangled in such host–guest systems. This also provides us with a flexible computational framework, useful to build structure–dynamics–property relationships for a variety of reactive host–guest systems.

Encapsulation of guests in metal–organic cages allows control over chemical reactivity. Focusing on the hydrolysis of amides, here we show an effective molecular simulation approach to reconstruct reactivity in host–guest systems in dynamic regimes.     

Docking rings in a solid: reversible assembling of pseudorotaxanes inside a zirconium metal–organic framework

An unprecedented zirconium metal–organic framework featuring a T-shaped benzimidazole strut was constructed and employed as a sponge-like material for selective absorption of macrocyclic guests. The neutral benzimidazole domain of the as-synthesized framework can be readily protonated and fully converted to benzimidazolium. Mechanical threading of [24]crown-8 ether wheels onto recognition sites to form pseudorotaxanes was evidenced by solution nuclear magnetic resonance, solid-state fluorescence, and infrared spectroscopy. Selective absorption of [24]crown-8 ether rather than its dibenzo counterpart was also observed. Further study reveals that this binding process is reversible and acid–base switchable. The success of docking macrocyclic guests in crystals via host–guest interactions provides an alternative route to complex functional materials with interpenetrated structures.

A T-shaped ligand was designed as struts for building a zirconium metal–organic framework. Acid–base switchable docking and releasing a 24-membered crown ether inside crystals was successfully accomplished via post-synthetic modification.     

Tunable Phosphorescence/Fluorescence Dual Emissions of Organic Isoquinoline-Benzophenone Doped Systems by Alkoxy Engineering

Dual/multi-component organic doped systems with room-temperature phosphorescence (RTP) properties have been developed. However, the unknown luminescence mechanism still greatly limits the development of the doped materials. Herein, a new doped system exhibiting phosphorescence/fluorescence dual emission (Φ_phos=4–24 % and τ_phos=101–343 ms) is successfully constructed through prediction and design. A series of isoquinoline derivatives with different alkoxy chains were selected as the guests. Benzophenone was chosen as the host owing to the characteristics of low melting point and good crystallinity. The alkoxy chain lengths of the guests are first reported to be used to control the fluorescence and phosphorescence intensities of the doped materials, which results in different prompt emission colors. Additionally, the doped ratio of the guest and host can also control the luminous intensities of the materials. In particular, the doped materials still exhibit phosphorescent properties even if the ratio of the guest/host is as low as 1:100 000.     

Lanthanide MOFs for inducing molecular chirality of achiral stilbazolium with strong circularly polarized luminescence and efficient energy transfer for color tuning

We present herein an innovative host–guest method to achieve induced molecular chirality from an achiral stilbazolium dye (DSM). The host–guest system is exquisitely designed by encapsulating the dye molecule in the molecule-sized chiral channel of homochiral lanthanide metal–organic frameworks (P-(+)/M-(−)-TbBTC), in which the P- or M-configuration of the dye is unidirectionally generated via a spatial confinement effect of the MOF and solidified by the dangling water molecules in the channel. Induced chirality of DSM is characterized by solid-state circularly polarized luminescence (CPL) and micro-area polarized emission of DSM@TbTBC, both excited with 514 nm light. A luminescence dissymmetry factor of 10⁻³ is obtained and the photoluminescence quantum yield (PLQY) of the encapsulated DSM in DSM@TbTBC is ∼10%, which is close to the PLQY value of DSM in dilute dichloromethane. Color-tuning from green to red is achieved, owing to efficient energy transfer (up to 56%) from Ln³⁺ to the dye. Therefore, this study for the first time exhibits an elegant host–guest system that shows induced strong CPL emission and enables efficient energy transfer from the host chiral Ln-MOF to the achiral guest DSM with the emission color tuned from green to red.

Homochiral Ln-MOFs are synthesized to encapsulate achiral dyes to induce strong circularly polarized luminescence with a luminescence dissymmetry factor of 10⁻³.     

Red aqueous room-temperature phosphorescence modulated by anion–π and intermolecular electronic coupling interactions

Aqueous room temperature phosphorescence (aRTP) from purely organic materials has been intriguing but challenging. In this article, we demonstrated that the red aRTP emission of 2Br–NDI, a water-soluble 4,9-dibromonaphthalene diimide derivative as a chloride salt, could be modulated by anion–π and intermolecular electronic coupling interactions in water. Specifically, the rarely reported stabilization of anion–π interactions in water between Cl⁻ and the 2Br–NDI core was experimentally evidenced by an anion–π induced long-lived emission (λ_Anion–π) of 2Br–NDI, acting as a competitive decay pathway against the intrinsic red aRTP emission (λ_Phos) of 2Br–NDI. In the initial expectation of enhancing the aRTP of 2Br–NDI by inclusion complexation with macrocyclic cucurbit[n]urils (CB[n]s, n = 7, 8, 10), we surprisingly found that the exclusion complexation between CB[8] and 2Br–NDI unconventionally endowed the complex with the strongest and longest-lived aRTP due to the strong intermolecular electronic coupling between the nπ* orbit on the carbonyl rims of CB[8] and the ππ* orbit on 2Br–NDI in water. It is anticipated that these intriguing findings may inspire and expand the exploration of aqueous anion–π recognition and CB[n]-based aRTP materials.

The aqueous room temperature phosphorescence of 2Br–NDI is modulated by long-lived-emitting anion–π interactions and tremendously enhanced by intermolecular electronic coupling interactions with the ISC-boosting carbonyl rims of CB[8] host.     

Binding site exchange kinetics revealed through efficient spin–spin dephasing of hyperpolarized 129Xe

Spin exchange between different chemical environments is an important observable for characterizing chemical exchange kinetics in various contexts, including protein folding, chelation chemistry, and host–guest interactions. Such spins experience effective spin–spin relaxation rate, R_2,eff, that typically shows a dispersive behavior which requires detailed analysis. Here, we describe a class of highly simplified R_2,eff behavior by relying on hyperpolarized ¹²⁹Xe as a freely exchanging ligand reporter. It provides large chemical shift separations that yield reduced expressions of both the Swift–Connick and the Carver–Richards treatment of exchange-induced relaxation. Despite observing a diamagnetic system, R_2,eff is dominated by large Larmor frequency jumps and thus allows detection of otherwise inaccessible analyte concentrations with a single spin echo train (only 0.01% of the overall hyperpolarized spins need to be transiently bound to the molecule). The two Xe hosts cryptophane-A monoacid (CrA-ma) and cucurbit[6]uril (CB6) represent two exemplary families of container molecules (the latter one also serving as drug delivery vehicles) that act as highly efficient phase shifters for which we observed unprecedented exchange-induced relaxivity r₂ (up to 866 s⁻¹ mM⁻¹). By including methods of spatial encoding, multiple data points can be collected simultaneously to isolate the exchange contribution and determine the effective exchange rate in partially occupied binding sites with a single delivery of hyperpolarized nuclei. The relaxivity is directly related to the guest turnover in these systems and temperature-dependent measurements yield an activation energy of E_A = 41 kJ mol⁻¹ for Xe@CrA-ma from simple relaxometry analysis. The concept is transferable to many applications where Xe is known to exhibit large chemical shifts.

Localized detection of hyperpolarized, exchanging Xe spins enables quantitative insights at unprecedented sensitivity for characterizing chemical exchange kinetics in various contexts such as host–guest interactions and displacement assays.     

Redox-responsive supramolecular polymeric networks having double-threaded inclusion complexes

Stimuli-responsive hydrogels have attracted attention as soft actuators that act similarly to muscles. In this work, hydrogel actuators controlled by host–guest interactions have been developed. The introduction of a 1:1 inclusion complex into a hydrogel is a popular design for achieving a change in cross-linking density. To realize faster and larger deformation properties, the introduction of a 1:2 inclusion complex is effective because the alteration in cross-linking density in a hydrogel with 1:2 complexes is larger than that in a hydrogel with 1:1 complexes. A redox-responsive hydrogel actuator cross-linked with 1:2 inclusion complexes is designed, where γ-cyclodextrin (γCD) and viologens modified with an alkyl chain derivative (VC11) were employed as the host and guest units, respectively. γCD includes two VC11 molecules in its cavity. The obtained γCD–VC11 hydrogel cross-linked with the 1:2 complex showed faster and larger deformation behaviour than the αCD–VC11 and the βCD–VC11 hydrogels cross-linked with a 1:1 complex. The deformation ratio and response speed of the γCD–VC11 hydrogel, which forms a supramolecular cross-linking structure by stimuli, are 3 and 11 times larger, respectively, than those of our previous hydrogel consisting of a βCD/ferrocene 1:1 inclusion complex.

A hydrogel actuator with a 1:2 host–guest complex controlled by redox stimuli has been developed to realize faster and larger deformation.     

Donor–acceptor–acceptor-type near-infrared fluorophores that contain dithienophosphole oxide and boryl groups: effect of the boryl group on the nonradiative decay

The use of donor–π–acceptor (D–π–A) skeletons is an effective strategy for the design of fluorophores with red-shifted emission. In particular, the use of amino and boryl moieties as the electron-donating and -accepting groups, respectively, can produce dyes that exhibit high fluorescence and solvatochromism. Herein, we introduce a dithienophosphole P-oxide scaffold as an acceptor–spacer to produce a boryl- and amino-substituted donor–acceptor–acceptor (D–A–A) π-system. The thus obtained fluorophores exhibit emission in the near-infrared (NIR) region, while maintaining high fluorescence quantum yields even in polar solvents (e.g. λ_em = 704 nm and Φ_F = 0.69 in CH₃CN). A comparison of these compounds with their formyl- or cyano-substituted counterparts demonstrated the importance of the boryl group for generating intense emission. The differences among these electron-accepting substituents were examined in detail using theoretical calculations, which revealed the crucial role of the boryl group in lowering the nonradiative decay rate constant by decreasing the non-adiabatic coupling in the internal conversion process. The D–A–A framework was further fine-tuned to improve the photostability. One of these D–A–A dyes was successfully used in bioimaging to visualize the blood vessels of Japanese medaka larvae and mouse brain.

Combination of electron-accepting diarylboryl terminal groups and dithienophosphole oxide spacers with electron-donating triarylamine moieties produces donor–acceptor–acceptor type π-systems, which exhibit emissions in the near-infrared region.     

Cucurbiturils brighten Au nanoclusters in water

Gold nanoclusters (AuNCs) with well-defined atomically precise structures present promising emissive prospects for excellent biocompatibility and optical properties. However, the relatively low luminescence efficiency in solutions for most AuNCs is still a perplexing issue to be resolved. In this study, a facile supramolecular strategy was developed to rigidify the surface of FGGC-AuNCs by modifying transition rates in excited states via host–guest self-assembly between cucurbiturils (CBs) and FGGC (Phe–Gly–Gly–Cys peptide). In aqueous solutions, CB/FGGC-AuNCs presented an extremely enhanced red phosphorescence emission with a quantum yield (QY) of 51% for CB[7] and 39% for CB[8], while simple FGGC-AuNCs only showed a weak emission with a QY of 7.5%. Furthermore, CB[7]/FGGC-AuNCs showed excellent results in live cell luminescence imaging for A549 cancer cells. Our study demonstrates that host–guest self-assembly assisted by macrocycles is a facile and effective tool to non-covalently modify and adjust optical properties of nanostructures on ultra-small scales.

A host–guest self-assembly approach was developed to brighten Au₂₂(FGGC)₁₈ nanoclusters between CB[n] (n = 7, 8) and FGGC peptide in aqueous solutions.     

Synthetic and computational assessment of a chiral metal–organic framework catalyst for predictive asymmetric transformation

Understanding and controlling molecular recognition mechanisms at a chiral solid interface is a continuously addressed challenge in heterogeneous catalysis. Here, the molecular recognition of a chiral peptide-functionalized metal–organic framework (MOF) catalyst towards a pro-chiral substrate is evaluated experimentally and in silico. The MIL-101 metal–organic framework is used as a macroligand for hosting a Noyori-type chiral ruthenium molecular catalyst, namely (benzene)Ru@MIL-101-NH-Gly-Pro. Its catalytic perfomance toward the asymmetric transfer hydrogenation (ATH) of acetophenone into R- and S-phenylethanol are assessed. The excellent match between the experimentally obtained enantiomeric excesses and the computational outcomes provides a robust atomic-level rationale for the observed product selectivities. The unprecedented role of the MOF in confining the molecular Ru-catalyst and in determining the access of the prochiral substrate to the active site is revealed in terms of highly face-specific host–guest interactions. The predicted surface-specific face differentiation of the prochiral substrate is experimentally corroborated since a three-fold increase in enantiomeric excess is obtained with the heterogeneous MOF-based catalyst when compared to its homogeneous molecular counterpart.

Understanding and controlling molecular recognition mechanisms at a chiral solid interface has been addressed in metal–organic framework catalysts for the asymmetric transfer hydrogenation reaction.     

Isomer recognition by dynamic guest-adaptive ligand rotation in a metal–organic framework with local flexibility

Local flexibility in a metal–organic framework is intriguing for reconstructing a microenvironment to distinguish different guest molecules by emphasizing their differences. Herein, guest-adaptive flexibility is observed in a metal–organic framework for efficiently discriminating aromatic isomers. Microcrystal electron diffraction directly reveals that the anthracene rings can rotate around the single bond with the adsorption of guest molecules. Disorder transformation of the ligand enables the preferential adsorption of ethylbenzene over other xylene isomers. Especially, a coated capillary column combining single/multi-component adsorption confirms a unique separation order of ethylbenzene > p-xylene > m-xylene > o-xylene with excellent selectivities, which has not been reported in other materials. Density functional theory calculations and the calculated Hirshfeld surface of guest molecules in the framework demonstrate that a guest-induced splint-like confinement structure makes the main contribution to such separation performance. This finding will provide a rational strategy for molecular recognition utilizing the local flexibility of metal–organic frameworks.

Local flexibility in a metal–organic framework is intriguing for reconstructing a microenvironment to distinguish different guest molecules by emphasizing their differences.     

Query-guided protein–protein interaction inhibitor discovery

Protein–protein interactions (PPIs) are central to biological mechanisms, and can serve as compelling targets for drug discovery. Yet, the discovery of small molecule inhibitors of PPIs remains challenging given the large and typically shallow topography of the interacting protein surfaces. Here, we describe a general approach to the discovery of orthosteric PPI inhibitors that mimic specific secondary protein structures. Initially, hot residues at protein–protein interfaces are identified in silico or from experimental data, and incorporated into secondary structure-based queries. Virtual libraries of small molecules are then shape-matched against the queries, and promising ligands docked to target proteins. The approach is exemplified experimentally using two unrelated PPIs that are mediated by an α-helix (p53/hDM2) and a β-strand (GKAP/SHANK1-PDZ). In each case, selective PPI inhibitors are discovered with low μM activity as determined by a combination of fluorescence anisotropy and ¹H–¹⁵N HSQC experiments. In addition, hit expansion yields a series of PPI inhibitors with defined structure–activity relationships. It is envisaged that the generality of the approach will enable discovery of inhibitors of a wide range of unrelated secondary structure-mediated PPIs.

Small-molecule protein–protein interaction inhibitors were prioritised on the basis of shape similarity to secondary structure-based queries incorporating hot-spot residues.     

A host–guest strategy for converting the photodynamic agents from a singlet oxygen generator to a superoxide radical generator

Type-I photosensitizers (PSs) generate cytotoxic oxygen radicals by electron transfer even in a hypoxic environment. Nevertheless, the preparation of type-I PSs remains a challenge due to the competition of triplet–triplet energy transfer with O₂ (type-II process). In this work, we report an effective strategy for converting the conventional type-II PS to a type-I PS by host–guest complexation. Electron-rich pillar[5]arenes are used as an electron donor and macrocyclic host to produce a host–guest complex with the traditional electron-deficient type-II PS, an iodide BODIPY-based guest. The host–guest complexation promotes intermolecular electron transfer from the pillar[5]arene moiety to BODIPY and then to O₂ by the type-I process upon light-irradiation, leading to efficient generation of the superoxide radical (O₂⁻˙). The results of anti-tumor studies indicate that this supramolecular PS demonstrates high photodynamic therapy efficacy even under hypoxic conditions. This work provides an efficient method to prepare type-I PSs from existing type-II PSs by using a supramolecular strategy.

A supramolecular strategy is reported for converting the conventional photodynamic agents from a singlet oxygen generator to a superoxide radical generator by the host–guest interaction enhanced electron transfer.     

Biphen[n]arenes

To design and exploit novel macrocyclic synthetic receptors is a permanent and challenging topic in supramolecular chemistry. Here we describe the one-pot synthesis, unique geometries and intriguing host–guest properties of a new class of supramolecular macrocycles – biphen[n]arenes (n = 3, 4), which are made up of 4,4′-biphenol or 4,4′-biphenol ether units linked by methylene bridges at the 3- and 3′- positions. The biphenarene macrocycles are conveniently accessible/modifiable and extremely guest-friendly. Particularly, biphen[4]arene is capable of forming inclusion complexes with not only organic cationic guests but also neutral π-electron deficient molecules. Compared with calixarenes, resorcinarenes, cyclotriveratrylenes and pillararenes with substituted mono-benzene units, the biphen[n]arenes reported here possess significantly different characteristics in both their topologic structures and their recognition properties, and thus can find broad applications in supramolecular chemistry and other areas.     

Modular synthesis,host–guest complexation and solvation-controlled relaxation of nanohoops with donor–acceptor structures

Carbon nanohoops with donor–acceptor (D–A) structures are attractive electronic materials and biological fluorophores, but their synthesis is usually challenging. Moreover, the preparation of D–A nanohoop fluorophores exhibiting high fluorescence quantum yields beyond 500 nm remains a key challenge. This study presents a modular synthetic approach based on an efficient metal-free cyclocondensation reaction that readily produced nine congeners with D–A or donor–acceptor–donor′ (D–A–D′) structures, one of which is water-soluble. The tailored molecular design of nanohoops enabled a systematic and detailed study of their host–guest complexation with fullerene, optical properties, and charge transfer (CT) dynamics using X-ray crystallography, fluorescence titration, steady and ultrafast transient absorption spectroscopy, and theoretical calculations. The findings revealed intriguing physical properties associated with D–A motifs, such as tight binding with fullerene, moderate fluorescence quantum yields (37–67%) beyond 540 nm, and unique solvation-controlled CT relaxation of D–A–D′ nanohoops, where two CT states (D–A and A–D′) can be effectively tuned by solvation, resulting in dramatically changed relaxation pathways in different solvents.

A modular synthetic approach based on cyclocondensation reaction is introduced to produce nine nanohoops with tunable donor–acceptor structures.     

Controlling the alignment of 1D nanochannel arrays in oriented metal–organic framework films for host–guest materials design

Controlling the direction of molecular-scale pores enables the accommodation of guest molecular-scale species with alignment in the desired direction, allowing for the development of high-performance mechanical, thermal, electronic, photonic and biomedical organic devices (host–guest approach). Regularly ordered 1D nanochannels of metal–organic frameworks (MOFs) have been demonstrated as superior hosts for aligning functional molecules and polymers. However, controlling the orientation of MOF films with 1D nanochannels at commercially relevant scales remains a significant challenge. Here, we report the fabrication of macroscopically oriented films of Cu-based pillar-layered MOFs having regularly ordered 1D nanochannels. The direction of 1D nanochannels is controllable by optimizing the crystal growth process; 1D nanochannels align either perpendicular or parallel to substrates, offering molecular-scale pore arrays for a macroscopic alignment of functional guest molecules in the desired direction. Due to the fundamental interest and widespread technological importance of controlling the alignment of functional molecules and polymers in a particular direction, orientation-controllable MOF films will open up the possibility of realising the potential of MOFs in advanced technologies.

Orientation-controlled Cu₂(Linker)₂DABCO MOF films on macroscopic scales are fabricated for the development of high-performance devices; the direction of 1D nanochannels is controllable either perpendicular or parallel to substrates.