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Autonomous laboratories can accelerate discoveries in chemical synthesis, but this requires automated measurements coupled with reliable decision-making 1 , 2 . Most autonomous laboratories involve bespoke automated equipment 3 – 6 , and reaction outcomes are often assessed using a single, hard-wired characterization technique 7 . Any decision-making algorithms 8 must then operate using this narrow range of characterization data 9 , 10 . By contrast, manual experiments tend to draw on a wider range of instruments to characterize reaction products, and decisions are rarely taken based on one measurement alone. Here we show that a synthesis laboratory can be integrated into an autonomous laboratory by using mobile robots 11 – 13 that operate equipment and make decisions in a human-like way. Our modular workflow combines mobile robots, an automated synthesis platform, a liquid chromatography–mass spectrometer and a benchtop nuclear magnetic resonance spectrometer. This allows robots to share existing laboratory equipment with human researchers without monopolizing it or requiring extensive redesign. A heuristic decision-maker processes the orthogonal measurement data, selecting successful reactions to take forward and automatically checking the reproducibility of any screening hits. We exemplify this approach in the three areas of structural diversification chemistry, supramolecular host–guest chemistry and photochemical synthesis. This strategy is particularly suited to exploratory chemistry that can yield multiple potential products, as for supramolecular assemblies, where we also extend the method to an autonomous function assay by evaluating host–guest binding properties. A modular autonomous platform for general exploratory synthetic chemistry uses mobile robots to integrate an automated synthesis platform and two analysis platforms.

Pure organic phosphorescence resonance energy transfer is a research hotspot. Herein, a single-molecule phosphorescence resonance energy transfer system with a large Stokes shift of 367 nm and near-infrared emission is constructed by guest molecule alkyl-bridged methoxy-tetraphenylethylene-phenylpyridines derivative, cucurbit[n]uril ( n  = 7, 8) and β -cyclodextrin modified hyaluronic acid. The high binding affinity of cucurbituril to guest molecules in various stoichiometric ratios not only regulates the topological morphology of supramolecular assembly but also induces different phosphorescence emissions. Varying from the spherical nanoparticles and nanorods for binary assemblies, three-dimensional nanoplate is obtained by the ternary co-assembly of guest with cucurbit[7]uril/cucurbit[8]uril, accompanying enhanced phosphorescence at 540 nm. Uncommonly, the secondary assembly of β -cyclodextrin modified hyaluronic acid and ternary assembly activates a single intramolecular phosphorescence resonance energy transfer process derived from phenyl pyridines unit to methoxy-tetraphenylethylene function group, enabling a near-infrared delayed fluorescence at 700 nm, which ultimately applied to mitochondrial targeted imaging for cancer cells. Phosphorescence resonance energy transfer systems have potential in light-harvesting and bioimaging, but host-guest systems are rarely explored. Here, the authors report the development of a macrocyclic host-guest system for targeted cell imaging.

Flexible hydrogen-bonded organic frameworks (FHOFs) are quite rare but promising for applications in separation, sensing and host-guest chemistry. They are difficult to stabilize, making their constructions a major challenge. Here, a flexible HOF (named 8PN) with permanent porosity has been successfully constructed. Nine single crystals of 8PN with different pore structures are obtained, achieving a large-scale void regulation from 4.4% to 33.2% of total cell volume. In response to external stimuli, multimode reversible structural transformations of 8PN accompanied by changes in luminescence properties have been realized. Furthermore, a series of high-quality co-crystals containing guests of varying shapes, sizes, aggregation states and even amounts are obtained, showing that 8PN can adapt to different guests by regulating the molecular conformations and assembling forms of its building blocks. The unexpected flexibility of 8PN makes it a promising material for enriching the applications of existing porous materials. Flexible hydrogen-bonded organic frameworks (FHOFs) are challenging in fabrication but promising materials for applications in separation and sensing. Here, the authors report a stimuli responsive and flexible HOF which can adapt to different guests by regulating the molecular conformation.

Rational design of robust photocatalytic systems to direct capture and in-situ convert diluted CO 2 from flue gas is a promising but challenging way to achieve carbon neutrality. Here, we report a new type of host-guest photocatalysts by integrating CO 2 -enriching ionic liquids and photoactive metal-organic frameworks PCN-250-Fe 2 M (M = Fe, Co, Ni, Zn, Mn) for artificial photosynthetic diluted CO 2 reduction in gas-solid phase. As a result, [Emim]BF 4 (39.3 wt%)@PCN-250-Fe 2 Co exhibits a record high CO 2 -to-CO reduction rate of 313.34 μmol g −1 h −1 under pure CO 2 atmosphere and 153.42 μmol g −1 h −1 under diluted CO 2 (15%) with about 100% selectivity. In scaled-up experiments with 1.0 g catalyst and natural sunlight irradiation, the concentration of pure and diluted CO 2 (15%) could be significantly decreased to below 85% and 10%, respectively, indicating its industrial application potential. Further experiments and theoretical calculations reveal that ionic liquids not only benefit CO 2 enrichment, but also form synergistic effect with Co 2+ sites in PCN-250-Fe 2 Co, resulting in a significant reduction in Gibbs energy barrier during the rate-determining step of CO 2 -to-CO conversion. Artificial photosynthetic diluted CO 2 reduction from fuel gas is promising but challenging for carbon neutrality. Here, the authors report a host-guest system by integrating CO 2 -enriching ionic liquids and photoactive metal-organic frameworks, greatly enhancing CO 2 -to-CO conversion efficiency.

Mono- or few-layer sheets of covalent organic frameworks (COFs) represent an attractive platform of two-dimensional materials that hold promise for tailor-made functionality and pores, through judicious design of the COF building blocks. But although a wide variety of layered COFs have been synthesized, cleaving their interlayer stacking to obtain COF sheets of uniform thickness has remained challenging. Here, we have partitioned the interlayer space in COFs by incorporating pseudorotaxane units into their backbones. Macrocyclic hosts based on crown ethers were embedded into either a ditopic or a tetratopic acylhydrazide building block. Reaction with a tritopic aldehyde linker led to the formation of acylhydrazone-based layered COFs in which one basal plane is composed of either one layer, in the case of the ditopic macrocyclic component, or two adjacent layers covalently held together by its tetratopic counterpart. When a viologen threading unit is introduced, the formation of a host–guest complex facilitates the self-exfoliation of the COFs into crystalline monolayers or bilayers, respectively.Layered COFs are attractive precursors for two-dimensional materials but they are difficult to cleave into mono- or few-layer sheets. Pseudorotaxane moieties have now been embedded into layered COFs to facilitate their cleavage into sheets of uniform thickness. Crown-ether macrocycles within the COF backbone bind to ionic viologen guests, leading to electrostatic repulsion between layers.

Size matching molecular design utilizing host-guest chemistry is a general, promising strategy for seeking new functional materials. With the growing trend of multidisciplinary investigations, taming the metastable high-energy guest moiety in well-matched frameworks is a new pathway leading to innovative energetic materials. Presented is a selective encapsulation in hydrogen-bonded hydroxylammonium frameworks (HHF) by screening different sized nitrogen-rich azoles. The size-match between a sensitive high-energy guest and an HHF not only gives rise to higher energetic performance by dense packing, but also reinforces the layer-by-layer structure which can stabilize the resulting materials towards external mechanic stimuli. Preliminary assessment based on calculated detonation properties and mechanical sensitivity indicates that HHF competed well with the energetic performance and molecular stability (detonation velocity = 9286 m s −1 , impact sensitivity = 50 J). This work highlights the size-matched phenomenon of HHF and may serve as an alternative strategy for exploring next generation advanced energetic materials. Size matching molecular design utilizing host-guest chemistry is a general and promising strategy for seeking new functional materials. Here the authors screen different sized nitrogen rich azoles for selective encapsulation into a hydroxylammonium framework to achieve a dense packing and higher energetic performance.

Paraquat, as one of the most widely used herbicides globally, is highly toxic to humans, and chronic exposure and acute ingestion leads to high morbidity and mortality rates. Here, we report user-friendly, photo-responsive paraquat-loaded supramolecular vesicles, prepared via one-pot self-assembly of amphiphilic, ternary host-guest complexes between cucurbit[8]uril, paraquat, and an azobenzene derivative. In this vesicle formulation, paraquat is only released upon UV or sunlight irradiation that converts the azobenzene derivative from its trans - to its  cis - form, which in turn dissociates the ternary host-guest complexations and the vesicles. The cytotoxicity evaluation of this vesicle formulation of paraquat on in vitro cell models, in vivo zebrafish models, and mouse models demonstrates an enhanced safety profile. Additionally, the PQ-loaded vesicles’ herbicidal activity against a model of invasive weed is nearly identical to that of free paraquat under natural sunlight. This study provides a safe yet effective herbicide formulation. Paraquat is a widely used herbicide that is highly toxic to humans upon acute ingestion or chronic exposure. Here, the authors generate a photosensitive formulation that releases paraquat upon exposure to UV light or sunlight, which shows an improved safety profile in zebrafish and mouse models, while maintaining substantial herbicidal activity.

Anti-Kasha’s process in organic luminogens has attracted many attentions since its discovery. However, only limited examples of anti-Kasha’s rule have been reported and anti-Kasha triplet energy transfer (ET) is even less-touched. Benefiting from anti-Kasha’s rule, this work provided an efficient strategy to realize excitation wavelength dependent (Ex-De) afterglow in a host-guest system. The host has almost imperceptible RTP upon 365 nm excitation and guest is totally RTP inactive, while the doping host-guest system exhibits Ex-De afterglow with improved quantum yields. Anti-Kasha triplet ET process is realized from the higher excited triplet state T 2 of host to the lowest excited singlet state S 1 of the aggregated/unimolecular guest . ET efficiency in the doping system could be tuned by simply changing its processing methods to guide host and guest to adopt denser or looser intermolecular packing. The strategy of anti-Kasha triplet ET endows the host-guest doping system with multiple stimuli-responsive properties, including Ex-De afterglow, mechano-, and thermal-triggered afterglow behaviors. The corresponding applications of these properties are also realized in multiple information anti-counterfeiting and display. Anti-Kasha processes have potential in organic luminogens, but design of materials with these characteristics is challenging. Here, the authors report the development of a host-guest system with anti-Kasha behaviour and triplet energy transfer.

Developing more extensive methods to understand the underlying structure-property relationship of mechanochromic luminescent molecules is demanding but remains challenging. Herein, the effect of host-guest interaction on the mechanochromic properties of organic molecules is illustrated. A series of pyridinium-functionalized triphenylamine derivatives show bathochromic-shifted emission upon mechanical stimulation. These derivatives bind to cucurbit[8]uril to form homoternary host-guest inclusion complexes through host-stabilized intermolecular charge transfer interactions. Remarkably, the homoternary complexes exhibit longer emission than that of free guests in the solid state (even longer than ground guests), and a further bathochromic-shifted emission is observed upon grinding. Additionally, a heteroternary complex constructed through the encapsulation of pyrene (donor) and pyridinium (acceptor) guest pair in cucurbit[8]uril also displays the mechanochromic luminescent property. This work not only discloses the effect of host-guest inclusion on the mechanochromic property of organic molecules, but also provides a principle and a facile way to design the sequentially red-shifted mechanochromic materials. The understanding of the structure-property relationship of mechanochromic luminescent molecules remains challenging. Here, the authors elucidate the effect of host-guest interactions on the mechanochromic properties of organic molecules.

Polycyclic aromatic hydrocarbons (PAHs) show promise for applications in functional devices such as organic photovoltaics and field-effect transistors, but, although nanometre-sized PAHs—often referred to as nanographenes—have been well investigated as single-layer molecules, their multilayer counterparts remain rather unexplored. Here we show the assembly of a C 64 nanographene derivative (comprising a planar core decorated with four meta -terphenyl–imide moieties at its periphery) into multilayer stacks with smaller PAHs ranging from naphthalene to ovalene and hexabenzocoronene. The functionalized C 64 nanographene serves as a ditopic host that can accommodate a smaller PAH on either side of its planar core, in cavities delimited by its bulky imide substituents. Bilayers and trilayers (that is, complexes with 1:1 and 1:2 host:guest ratios, respectively) were observed in solution, and dimers of these complexes as well as multilayer compounds were isolated in the solid state. Quantum-chemical calculations indicate that dispersion forces are the main stabilizing factor for these complexes. Nanometre-sized polyaromatic hydrocarbons (nanographenes) have been largely explored as single-layer systems. Now a C 64 nanographene comprising a planar core decorated with four terphenyl–imide moieties at its periphery has been shown to assemble with coronene to form bi- and trilayer host–guest complexes in solution, as well as tetra-, hexa- and multilayer stacks in the crystalline state.