Active mechanisorption driven by pumping cassettes

A Multiresponsive Ferrocene-Based Chiral Overcrowded Alkene Twisting Liquid Crystals

The reversible modulation of chirality has gained significant attention not only for fundamental stereochemical studies but also for numerous applications ranging from liquid crystals (LCs) to molecular motors and machines. This requires the construction of switchable molecules with (multiple) chiral elements in a highly enantioselective manner, which is often a significant synthetic challenge. Here, we show that the dimerization of an easily accessible enantiopure planar chiral ferrocene-indanone building block affords a multi-stimuli-responsive dimer (FcD) with pre-determined double bond geometry, helical chirality, and relative orientation of the two ferrocene motifs in high yield. This intrinsically planar chiral switch can not only undergo thermal or photochemical E/Z isomerization but can also be reversibly and quantitatively oxidized to both a monocationic and a dicationic state which is associated with significant changes in its (chir)optical properties. Specifically, FcD acts as a chiral dopant for cholesteric LCs with a helical twisting power (HTP) of 13 μm-1 which, upon oxidation, drops to near zero, resulting in an unprecedently large redox-tuning of the LC reflection color by up to 84 nm. Due to the straightforward stereoselective synthesis, FcD, and related chiral switches, are envisioned to be powerful building blocks for multi-stimuli-responsive molecular machines and in LC-based materials.

Transducing chemical energy through catalysis by an artificial molecular motor

Cells display a range of mechanical activities generated by motor proteins powered through catalysis1. This raises the fundamental question of how the acceleration of a chemical reaction can enable the energy released from that reaction to be transduced (and, consequently, work to be done) by a molecular catalyst2-7. Here we demonstrate the molecular-level transduction of chemical energy to mechanical force8 in the form of the powered contraction and powered re-expansion of a cross-linked polymer gel driven by the directional rotation of artificial catalysis-driven9 molecular motors. Continuous 360° rotation of the rotor about the stator of the catalysis-driven motor-molecules incorporated in the polymeric framework of the gel twists the polymer chains of the cross-linked network around one another. This progressively increases writhe and tightens entanglements, causing a macroscopic contraction of the gel to approximately 70% of its original volume. The subsequent addition of the opposite enantiomer fuelling system powers the rotation of the motor-molecules in the reverse direction, unwinding the entanglements and causing the gel to re-expand. Continued powered twisting of the strands in the new direction causes the gel to re-contract. In addition to actuation, motor-molecule rotation in the gel produces other chemical and physical outcomes, including changes in the Young modulus and storage modulus-the latter is proportional to the increase in strand crossings resulting from motor rotation. The experimental demonstration of work against a load by a synthetic organocatalyst, and its mechanism of energy transduction6, informs both the debate3,5,7 surrounding the mechanism of force generation by biological motors and the design principles6,10-14 for artificial molecular nanotechnology.

Efficient removal of Cr (VI) by Bifunction zinc porphyrin COF: Coupling adsorption with Photocatalysis, performance Evaluation, and mechanism analysis

HYPOTHESIS

Hexavalent chromium, recognized as one of the most toxic heavy metals, demands the development of advanced materials capable of both adsorption and photocatalysis for effective Cr (VI) removal.

EXPERIMENTS

This study successfully synthesized a two-dimensional zinc porphyrin covalent organic framework (ZnPor-COF) via a solvent-based method. Performance evaluations have demonstrated that the ZnPor-COF possesses outstanding capabilities for the adsorptive and/or photocatalytic elimination of Cr (VI). Particularly noteworthy is the observation that when adsorption and photocatalysis are coupled, the ZnPor-COF attains an exceptional 99.7 % removal rate for a Cr (VI) concentration of 30 mg/L within just 60 min, with minimal susceptibility to coexisting ions. After five consecutive cycles, the material sustains a removal efficiency of 90 %, indicative of its robust cyclability.

FINDINGS

Theoretical calculations, as well as experimental validations, have indicated that the integration of Zn ions into the porphyrin COF not only results in an expanded specific surface area and an increased count of adsorption sites but also significantly improves the COF's photosensitivity and the capability for charge carrier separation. Furthermore, the core of the synergistic effect between adsorption and photocatalysis lies in the ability of photocatalysis to substantially augment the adsorption process.

Tailoring rhodium-based metal-organic layers for parahydrogen-induced polarization: achieving 20% polarization of 1H in liquid phase

Heterogeneous catalysts for parahydrogen-induced polarization (HET-PHIP) would be useful for producing highly sensitive contrasting agents for magnetic resonance imaging (MRI) in the liquid phase, as they can be removed by simple filtration. Although homogeneous hydrogenation catalysts are highly efficient for PHIP, their sensitivity decreases when anchored on porous supports due to slow substrate diffusion to the active sites and rapid depolarization within the channels. To address this challenge, we explored 2D metal-organic layers (MOLs) as supports for active Rh complexes with diverse phosphine ligands and tunable hydrogenation activities, taking advantage of the accessible active sites and chemical adaptability of the MOLs. By adjusting the electronic properties of phosphines, TPP-MOL-Rh-dppb (TPP = tris(4-carboxylphenyl)phosphine), featuring a κ 2-connected di(phosphine) ligand, generated hyperpolarized styrene achieving an over-2400-fold signal enhancement and a polarization level of 20% for 1H in methanol-d 4 solution. The TPP-MOL-Rh-dppb effectively inherited the high efficiency and pairwise addition of its homogenous catalyst while maintaining the heterogeneity of MOLs. This work demonstrates the potential of 2D phosphine-functionalized MOLs as heterogeneous solid support for HET-PHIP.

Allosteric release of cucurbit[6]uril from a rotaxane using a molecular signal

Rotaxanes can be regarded as storage systems for their wheel components, which broadens their application potential as a complement to the supramolecular systems that retain a mechanically interlocked structure. However, utilising rotaxanes in this way requires a method to release the wheel while preserving the integrity of all molecular constituents. Herein, we present simple rotaxanes based on cucurbit[6]uril (CB6), with an axis equipped with an additional binding motif that enables the binding of another macrocycle, cucurbit[7]uril (CB7). We demonstrate that the driving force behind the wheel dethreading originates from the binding of the signalling macrocycle to the allosteric site, leading to an increase in the system's strain. Consequently, the CB6 wheel leaves the rotaxane station overcoming the mechanical barrier. Portal-portal repulsive interactions between the two cucurbituril units play a crucial role in this process. Thus, the repulsive strength and the related rate of slipping off can be finely tuned by the length of the allosteric binding motif. Finally, we show that the CB6 wheel can be utilised within complexes with other guests in the mixture once released from the rotaxane.

Two-Periodic MoS2-Type Metal-Organic Frameworks with Intrinsic Intralayer Porosity for High-Capacity Water Sorption

2D metal-organic frameworks (2D-MOFs) are an important class of functional porous materials. However, the low porosity and surface area of 2D-MOFs have greatly limited their functionalities and applications. Herein, the rational synthesis of a class of mos-MOFs with molybdenum disulfide (mos) net based on the assembly of trinuclear metal clusters and 3-connected tripodal organic ligands is reported. The non-crystallographic (3,6)-connected mos net, different from the 3-connected hcb net of graphene, offers abundant intralayer voids courtesy of the split of one node into two. Indeed, mos-MOFs exhibit high apparent Brunauer-Emmett-Teller surface areas, significantly superior to those of other 2D-MOF analogs. Markedly, hydrolytically stable Cr-mos-MOF-1 displays an impressive water vapor uptake of 0.75 g g-1 at 298 K and P/P0 = 0.9, among the highest in 2D-MOFs. The combined water adsorption and X-ray diffraction study reveal the water adsorption mechanisms, suggesting the importance of intralayer porosities of mos-MOFs for high-performance water capture. This study paves the way for a reliable approach to synthesizing 2D-MOFs with high porosity and surface areas for diverse applications.

Coupling Rotary Motion to Helicene Inversion within a Molecular Motor

Towards complex coupled molecular motions, the remote handedness inversion of a helicene moiety was achieved by a rotary molecular motor. The use of a specifically engineered dynamic helicene stator in a novel overcrowded-alkene second-generation molecular motor based on a fluorinated dibenzofluorene fragment allows for an unprecedented control over helicity inversion. This is achieved by the mechanical coupling of the rotation of the rotor to the helicene inversion of the stator half via a remote chirality transmission process. Thus, the unidirectional rotary motion generated upon irradiation is used to invert the dynamic stereochemistry of a helicene, leading to a 6-step cycle with eight intermediates. In this cycle, both alternation between P and M configurations of the helicene stator and dynamic thermal interconversion (paddling motion) can be achieved. In-depth computational and spectroscopic studies were performed to support the associated mechanism. The control over coupled motion and dynamic helicity offers prospects for the development of complex responsive systems.

Molecular cylinders with donor-acceptor structure and swinging motion

The construction of three-dimensional nanocarbon structures with well-defined molecular dynamics is a challenging yet rewarding task in material science and supramolecular chemistry. Herein, we report the synthesis of two highly defective, nitrogen-doped molecular cylinders, namely MC1 and MC2, with a length of 1.4 nm and 2.7 nm, respectively. These molecular cylinders are constructed by connecting the cycloparaphenylene endcaps and fused aromatic pillars using a cyclocondensation reaction, affording a distinct donor-acceptor structure. An X-ray crystallographic analysis reveals a tilted cylindrical shape for MC1, and nuclear magnetic resonance spectroscopy and calculations indicate the occurrence of a dynamic swinging motion in solution. The elongation of conjugation in the cylinders attenuates the charge transfer character in the first excited state, resulting in remarkable length-dependent photophysical properties.

Concise and Efficient Synthesis of Sequentially Isomeric Hetero[3]rotaxanes

Stereoisomerism, stemming from the spatial orientation of components in molecular structures, plays a decisive role in nature. While the unconventional bonding found in mechanically interlocked molecules gives rise to unique expressions of stereochemistry, the exploration of their stereoisomers is still in its infancy. Sequence isomerism, characterized by variations in the ordering of mechanically interlocked components in catenanes and rotaxanes, mirrors the sequence variations found in biological macromolecules. Herein, we report the use of artificial molecular pumps for the precise and simple production of sequentially isomeric hetero[3]rotaxanes. Utilizing redox-driven pumping cassettes with different rings, we have synthesized two hetero[3]rotaxane isomers in high isolated yields from two [2]rotaxanes. This research represents a significant advance in sequential molecular assembly, paving the way for the development of sophisticated, functionalized, mechanically interlocked materials.

Harnessing Radicals: Advances in Self-Assembly and Molecular Machinery

Radicals, with their unpaired electrons, exhibit unique chemical and physical properties that have long intrigued chemists. Despite early skepticism about their stability, the discovery of persistent radicals has opened new possibilities for molecular interactions. This review examines the mechanisms and applications of radically driven self-assembly, focusing on key motifs such as naphthalene diimides, tetrathiafulvalenes, and viologens, which serve as models for radical assembly. The potential of radical interactions in the development of artificial molecular machines (AMMs) are also discussed. These AMMs, powered by radical-radical interactions, represent significant advancements in non-equilibrium chemistry, mimicking the functionalities of biological systems. From molecular switches to ratchets and pumps, the versatility and unique properties of radically powered AMMs are highlighted. Additionally, the applications of radical assembly in materials science are explored, particularly in creating smart materials with redox-responsive properties. The review concludes by comparing AMMs to biological molecular machines, offering insights into future directions. This overview underscores the impact of radical chemistry on molecular assembly and its promising applications in both synthetic and biological systems.

Mechanical Regulation of Polymer Gels

The mechanical properties of polymer gels devote to emerging devices and machines in fields such as biomedical engineering, flexible bioelectronics, biomimetic actuators, and energy harvesters. Coupling network architectures and interactions has been explored to regulate supportive mechanical characteristics of polymer gels; however, systematic reviews correlating mechanics to interaction forces at the molecular and structural levels remain absent in the field. This review highlights the molecular engineering and structural engineering of polymer gel mechanics and a comprehensive mechanistic understanding of mechanical regulation. Molecular engineering alters molecular architecture and manipulates functional groups/moieties at the molecular level, introducing various interactions and permanent or reversible dynamic bonds as the dissipative energy. Molecular engineering usually uses monomers, cross-linkers, chains, and other additives. Structural engineering utilizes casting methods, solvent phase regulation, mechanochemistry, macromolecule chemical reactions, and biomanufacturing technology to construct and tailor the topological network structures, or heterogeneous modulus compositions. We envision that the perfect combination of molecular and structural engineering may provide a fresh view to extend exciting new perspectives of this burgeoning field. This review also summarizes recent representative applications of polymer gels with excellent mechanical properties. Conclusions and perspectives are also provided from five aspects of concise summary, mechanical mechanism, biofabrication methods, upgraded applications, and synergistic methodology.

Two-Dimensional Metal-Organic Frameworks/Epoxy Composite Coatings with Superior O2/H2O Resistance for Anticorrosion Applications

Corrosion protection technology plays a crucial role in preserving infrastructure, ensuring safety and reliability, and promoting long-term sustainability. In this study, we combined experiments and various analyses to investigate the mechanism of corrosion occurring on the epoxy-based anticorrosive coating containing the additive of two-dimensional (2D) and water-stable zirconium-based metal-organic frameworks (Zr-MOFs). By using benzoic acid as the modulator for the growth of the MOF, a 2D MOF constructed from hexazirconium clusters and BTB linkers (BTB = 1,3,5-tri(4-carboxyphenyl)benzene) with coordinated benzoate (BA-ZrBTB) can be synthesized. By coating the BA-ZrBTB/epoxy composite film (BA-ZrBTB/EP) on the surface of cold-rolled steel (CRS), we found the lowest coating roughness (RMS) of BA-ZrBTB/EP is 2.83 nm with the highest water contact angle as 99.8°, which represents the hydrophobic coating surface. Notably, the corrosion rate of the BA-ZrBTB/EP coating is 2.28 × 10-3 mpy, which is 4 orders of magnitude lower than that of the CRS substrate. Moreover, the energy barrier for oxygen diffusion through BA-ZrBTB/EP coating is larger than that for epoxy coating (EP), indicating improved oxygen resistance for adding 2D Zr-MOFs as the additive. These results underscore the high efficiency and potential of BA-ZrBTB as a highly promising agent for corrosion prevention in various commercial applications. Furthermore, this study represents the first instance of applying 2D Zr-MOF materials in anticorrosion applications, opening up new possibilities for advanced corrosion-resistant coatings.

Self-Assembled Bis-Acridinium Tweezer Equilibria Controlled by Multi-Responsive Properties

Protonated and methylated bis-acridinium tweezers built around a 2,6-diphenylpyridyl and an electron enriched 2,6-di(p-anisyl)pyridyl spacer have been synthesized. These tweezers can self-assemble in their corresponding homodimers and the associated thermodynamic parameters have been probed in organic solvents. The switching properties of the tweezers have been exploited in biphasic transfer experiments showing the shift of the equilibria towards the homodimers. Moreover, the thermodynamic parameters of the formation of the reduced methylated homodimers investigated by electrochemical experiments revealed the dissociation of the dimers. Thus, in addition to solvent and temperature, the pH and redox responsiveness of the acridinium units of the tweezers make it possible to modulate to a larger extent the monomer-dimer equilibria.

A molecular anion pump

Pumping ions against a concentration gradient through protein-based transporters is a cornerstone of numerous biological processes. Mimicking this function by using artificial receptors remains a daunting challenge, mainly because of the difficulties in balancing between the requirement for high binding affinities and precise and on-demand ion capture and release properties. We report a trimeric hydrazone photoswitch-based receptor that converts light energy into work by actively transporting chloride anion against a gradient through a dichloromethane liquid membrane, functioning as a molecular pump. The system manifests ease of synthesis, bistability, excellent photoswitching properties, and superb ON-OFF binding properties (difference of up to six orders of magnitude).

Programmable Lanthanide Metal-Organic Framework for Ultra-Efficient Nucleic Acids Extraction and Interaction Analysis

Efficient, mild, and reversible adsorption of nucleic acids onto nanomaterials represents a promising analytical approach for medical diagnosis. However, there is a scarcity of efficient and reversible nucleic acid adsorption nanomaterials. Additionally, the lack of comprehension of the molecular mechanisms governing their interactions poses significant challenges. These issues hinder the rational design and analytical applications of the nanomaterials. Herein, we propose an ultra-efficient nucleic acid affinity nanomaterial based on programmable lanthanide metal-organic frameworks (Ln-MOFs). Through experiments and density functional theory calculations, a rational design guideline for nucleic acid affinity of Ln-MOF was proposed, and a modular and flexible preparation scheme was provided. Then, Er-TPA (terephthalic acid) MOF emerged as the optimal candidate due to its pore size-independent adsorption and desorption capabilities for nucleic acids, enabling ultra-efficient adsorption (about 150% mass ratio) within 1 min. Furthermore, we elucidate the molecular-level mechanisms underlying the Ln-MOF adsorption of single- and double-stranded DNA and G4 structures. The affinity nanomaterial based on Ln-MOF exhibits robust nucleic acid extraction capability (4-fold higher than commercial reagent kits) and enables mild and reversible CRISPR/Cas9 functional regulation. This method holds significant promise for broad application in DNA/RNA liquid biopsy and gene editing, facilitating breakthroughs in analytical chemistry, pharmacy, and medical research.

Immobilization of europium and terbium ions with tunable ratios on a dispersible two-dimensional metal-organic framework for ratiometric photoluminescence detection of D2O

A two-dimensional zirconium-based metal-organic framework (2D Zr-MOF), ZrBTB (BTB = 1,3,5-tri(4-carboxyphenyl)benzene), is used as a platform to simultaneously immobilize terbium ions and europium ions with tunable ratios on its hexa-zirconium nodes by a post-synthetic modification. The crystallinity, morphology, porosity and photoluminescence (PL) properties of the obtained 2D Zr-MOFs with various europium-to-terbium ratios are investigated. With the energy transfer from the excited BTB linker to the installed terbium ions and the energy transfer from terbium ions to europium ions, a low loading of immobilized europium ions and a high loading of surrounding terbium ions in the 2D Zr-MOF result in the optimal PL emission intensities of europium; this phenomenon is not observable for the physical mixture of both terbium-installed ZrBTB and europium-installed ZrBTB. The role of installed terbium ions as efficient mediators for the energy transfer from the excited BTB linker to the installed europium ion is confirmed by quantifying PL quantum yields. As a demonstration, these materials with modulable PL characteristics are applied for the ratiometric detection of D2O in water, with the use of the stable emission from the BTB linker as the reference. With the strong emission of immobilized europium ions and the good dispersity in aqueous solutions, the optimal bimetal-installed ZrBTB, Eu-Tb-ZrBTB(1 : 10), can achieve the sensing performance outperforming those of the terbium-installed ZrBTB, europium-installed ZrBTB and the physical mixture of both.

Ultrafine CuO/graphene oxide cellulose nanocomposites with complementary framework for polycyclic aromatic hydrocarbon pollutants removal

Efficient and sustainable methods for eliminating polycyclic aromatic hydrocarbon pollutants (PAHPs) are in highly desired. Proven technologies involve physical and chemical reactions that absorb PAHPs, however they encounter formidable challenges. Here, a bottom-up refining-grain strategy is proposed to rationally design ultrafine CuO/graphene oxide-cellulose nanocomposites (LCelCCu) with a mirror-like for tetracycline (TC) to substantially improve the efficient of the purification process by active integrated-sorption. The LCelCCu captures TC with a higher affinity and lower energy demand, as determined by sorption kinetic, isotherms, thermodynamics, and infrared and X-ray Photoelectron Spectroscopy. The resulting material could achieve ultra-high sorption capacity (2775.23 mg/g), kinetic (1.2499 L g-1 h-1) and high selectivity (up to 99.9 %) for TC, nearly surpassing all recent adsorbents. This study simultaneously unveils the pioneering role of simultaneous multi-site match sorption and subsequent advanced oxidation synergistically, fundamentally enhancing understanding of the structure-activity-selectivity relationship and inspires more sustainable water purification applications and broader material design considerations.

Mechanical bonding of rigid MORFs using a tetratopic rotaxane

The preparation of highly rigid cobalt(II)- and copper(II)-organic frameworks incorporating a tetralactam [2]rotaxane as a ligand is described. The interlocked ligand is functionalized with two pairs of carboxylate groups placed at each counterpart, thus limiting its dynamics within the crystal. The solid structure of the metal-organic rotaxane frameworks showed different, unprecedented polycatenation modes of grids, depending on the employed metal, providing great rigidity to the structures. This rigidity has been evaluated by using single crystal X-ray diffraction analyses of the cobalt(II)-organic frameworks embedded in different solvents, observing that the lattices remain unchanged. Thus, this research demonstrates that rigid and robust materials with permanent porosity can be achieved using dynamic ligands.

Reticular Ratchets for Directing Electrochemiluminescence

Electrochemiluminescence (ECL) involves charge transfer between electrochemical redox intermediates to produce an excited state for light emission. Ensuring precise control of charge transfer is essential for decoding ECL fundamentals, yet guidelines on how to achieve this for conventional emitters remain unexplored. Molecular ratchets offer a potential solution, as they enable the directional transfer of energy or chemicals while impeding the reverse movement. Herein, we designed 10 pairs of imine-based covalent organic frameworks as reticular ratchets to delicately manipulate the intrareticular charge transfer for directing ECL transduction from electric and chemical energies. Aligning the donor and acceptor (D-A) directions with the imine dipole effectively facilitates charge migration, whereas reversing the D-A direction impedes it. Notably, the ratchet effect of charge transfer directionality intensified with increasing D-A contrast, resulting in a remarkable 680-fold improvement in the ECL efficiency. Furthermore, dipole-controlled exciton binding energy, electron/hole decay kinetics, and femtosecond transient absorption spectra identified the electron transfer tendency from the N-end toward the C-end of reticular ratchets during ECL transduction. An exponential correlation between the ECL efficiency and the dipole difference was discovered. Our work provides a general approach to manipulate charge transfer and design next-generation electrochemical devices.

Molecular Ratchets and Kinetic Asymmetry: Giving Chemistry Direction

Over the last two decades ratchet mechanisms have transformed the understanding and design of stochastic molecular systems-biological, chemical and physical-in a move away from the mechanical macroscopic analogies that dominated thinking regarding molecular dynamics in the 1990s and early 2000s (e.g. pistons, springs, etc), to the more scale-relevant concepts that underpin out-of-equilibrium research in the molecular sciences today. Ratcheting has established molecular nanotechnology as a research frontier for energy transduction and metabolism, and has enabled the reverse engineering of biomolecular machinery, delivering insights into how molecules 'walk' and track-based synthesisers operate, how the acceleration of chemical reactions enables energy to be transduced by catalysts (both motor proteins and synthetic catalysts), and how dynamic systems can be driven away from equilibrium through catalysis. The recognition of molecular ratchet mechanisms in biology, and their invention in synthetic systems, is proving significant in areas as diverse as supramolecular chemistry, systems chemistry, dynamic covalent chemistry, DNA nanotechnology, polymer and materials science, molecular biology, heterogeneous catalysis, endergonic synthesis, the origin of life, and many other branches of chemical science. Put simply, ratchet mechanisms give chemistry direction. Kinetic asymmetry, the key feature of ratcheting, is the dynamic counterpart of structural asymmetry (i.e. chirality). Given the ubiquity of ratchet mechanisms in endergonic chemical processes in biology, and their significance for behaviour and function from systems to synthesis, it is surely just as fundamentally important. This Review charts the recognition, invention and development of molecular ratchets, focussing particularly on the role for which they were originally envisaged in chemistry, as design elements for molecular machinery. Different kinetically asymmetric systems are compared, and the consequences of their dynamic behaviour discussed. These archetypal examples demonstrate how chemical systems can be driven inexorably away from equilibrium, rather than relax towards it.

A Minimalistic Covalent Bond-Forming Chemical Reaction Cycle that Consumes Adenosine Diphosphate

The development of synthetic active matter requires the ability to design materials capable of harnessing energy from a source to carry out work. Nature achieves this using chemical reaction cycles in which energy released from an exergonic chemical reaction is used to drive biochemical processes. Although many chemically fuelled synthetic reaction cycles that control transient responses, such as self-assembly, have been reported, the generally high complexity of the reported systems hampers a full understanding of how the available chemical energy is actually exploited by these systems. This lack of understanding is a limiting factor in the design of chemically fuelled active matter. Here, we report a minimalistic synthetic responsive reaction cycle in which adenosine diphosphate (ADP) triggers the formation of a catalyst for its own hydrolysis. This establishes an interdependence between the concentrations of the network components resulting in the transient formation of the catalyst. The network is sufficiently simple that all kinetic and thermodynamic parameters governing its behaviour can be characterised, allowing kinetic models to be built that simulate the progress of reactions within the network. While the current network does not enable the ADP-hydrolysis reaction to populate a non-equilibrium composition, these models provide insight into the way the network dissipates energy. Furthermore, essential design principles are revealed for constructing driven systems, in which the network composition is driven away from equilibrium through the consumption of chemical energy.

Two-dimensional metal-organic framework for post-synthetic immobilization of graphene quantum dots for photoluminescent sensing

Immobilization of graphene quantum dots (GQDs) on a solid support is crucial to prevent GQDs from aggregation in the form of solid powder and facilitate the separation and recycling of GQDs after use. Herein, spatially dispersed GQDs are post-synthetically coordinated within a two-dimensional (2D) and water-stable zirconium-based metal-organic framework (MOF). Unlike pristine GQDs, the obtained GQDs immobilized on 2D MOF sheets show photoluminescence in both suspension and dry powder. Chemical and photoluminescent stabilities of MOF-immobilized GQDs in water are investigated, and the use of immobilized GQDs in the photoluminescent detection of copper ions is demonstrated. Findings here shed the light on the use of 2D MOFs as a platform to further immobilize GQDs with various sizes and distinct chemical functionalities for a range of applications.

Molecular Motors' Magic Methyl and Its Pivotal Influence on Rotation

Molecular motors have found a wide range of applications, powering a transition from molecules to dynamic molecular systems for which their motion must be precisely tuned. To achieve this adjustment, strategies involving laborious changes in their design are often used. Herein, we show that control over a single methyl group allows a drastic change in rotational properties. In this regard, we present the straightforward asymmetric synthesis of β-methylated first-generation overcrowded-alkene-based molecular motors. Both enantiomers of the new motors were prepared in good yields and high enantiopurities, and these motors were thoroughly studied by variable-temperature nuclear magnetic resonance (VT-NMR), ultraviolet-visible (UV-vis), and circular dichroism (CD) spectroscopy, showing a crucial influence of the methylation pattern on the rotational behavior of the motors. Starting from a common chiral precursor, we demonstrate that subsequent methylation can drastically reduce the speed of the motor and reverse the direction of the rotation. We show for the first time that complete unidirectionality can be achieved even when the energy difference between the stable and metastable states is small, resulting in the coexistence of both states under ambient conditions without hampering the energy ratcheting process. This discovery opens the way for the design of more advanced first-generation motors.

Modulated Self-Assembly of Catalytically Active Metal-Organic Nanosheets Containing Zr6 Clusters and Dicarboxylate Ligands

Two-dimensional metal-organic nanosheets (MONs) have emerged as attractive alternatives to their three-dimensional metal-organic framework (MOF) counterparts for heterogeneous catalysis due to their greater external surface areas and higher accessibility of catalytically active sites. Zr MONs are particularly prized because of their chemical stability and high Lewis and Brønsted acidities of the Zr clusters. Herein, we show that careful control over modulated self-assembly and exfoliation conditions allows the isolation of the first example of a two-dimensional nanosheet wherein Zr6 clusters are linked by dicarboxylate ligands. The hxl topology MOF, termed GUF-14 (GUF = Glasgow University Framework), can be exfoliated into monolayer thickness hns topology MONs, and acid-induced removal of capping modulator units yields MONs with enhanced catalytic activity toward the formation of imines and the hydrolysis of an organophosphate nerve agent mimic. The discovery of GUF-14 serves as a valuable example of the undiscovered MOF/MON structural diversity extant in established metal-ligand systems that can be accessed by harnessing the power of modulated self-assembly protocols.

Synthesis of 'Impossible' Rotaxanes

'Impossible' rotaxanes, which are constituted by interlocked components without obvious binding motifs, have attracted the interest of the mechanically interlocked molecules (MIMs) community. Within the synthetic efforts reported in the last decades towards the preparation of MIMs, some innovative protocols for accessing 'impossible' rotaxanes have been developed. This short review highlights different selected synthetic examples of 'impossible' rotaxanes, as well as suggests some future directions of this research area.

Adaptisorption of Nonporous Polymer Crystals

Although our knowledge and understanding of adsorptions in natural and artificial systems has increased dramatically during the past century, adsorption associated with nonporous polymers remains something of a mystery, hampering applications. Here we demonstrate a model system for adaptisorption of nonporous polymers, wherein dative B-N bonds and host-guest binding units act as the kinetic and thermodynamic components, respectively. The coupling of these two components enables nonporous polymer crystals to adsorb molecules from solution and undergo recrystallization as thermodynamically favored crystals. Adaptisorption of nonporous polymer crystals not only extends the types of adsorption in which the sorbate molecules are integrated in a precise and orderly manner in the sorbent systems, but also provides a facile and accurate approach to the construction of polymeric materials with precise architectures and integrated functions.

Polar alcohol guest molecules regulate the stacking modes of 2-D MOF nanosheets

The modulation of two-dimensional metal-organic framework (2-D MOF) nanosheet stacking is an effective means to improve the properties and promote the application of nanosheets in various fields. Here, we employed a series of alcohol guest molecules (MeOH, EtOH and PrOH) to modulate Zr-BTB (BTB = benzene-1,3,5-tribenzoate) nanosheets and to generate untwisted stacking. The distribution of stacking angles was statistically analyzed from high-angle annular dark-field (HAADF) and fast Fourier transform (FFT) images. The ratios of untwisted stacking were calculated, such as 77.01% untwisted stacking for MeOH, 83.45% for EtOH, and 85.61% for PrOH. The obtained untwisted Zr-BTB showed good separation abilities for different substituted benzene isomers, superior para selectivity and excellent column stability and reusability. Control experiments of 2-D Zr-TCA (TCA = 4,4',4''-tricarboxytriphenylamine) and Zr-TATB (TATB = 4,4',4''-(1,3,5-triazine-2,4,6-triyl)tribenzoic acid) nanosheets with similar pore sizes and stronger polarity regulated by the alcohol guests exhibited moderate separation performance. The electron microscopy images revealed that polar alcohol regulation dominantly generated the twisted stacking of Zr-TCA and Zr-TATB with various Moiré patterns. Polar guest molecules, such as alcohols, provide strong host-guest interactions during the regulation of MOF nanosheet stacking, providing an opportunity to design new porous Moiré materials with application prospects.

Kinetic Asymmetry and Directionality of Nonequilibrium Molecular Systems

Scientists have long been fascinated by the biomolecular machines in living systems that process energy and information to sustain life. The first synthetic molecular rotor capable of performing repeated 360° rotations due to a combination of photo- and thermally activated processes was reported in 1999. The progress in designing different molecular machines in the intervening years has been remarkable, with several outstanding examples appearing in the last few years. Despite the synthetic accomplishments, there remains confusion regarding the fundamental design principles by which the motions of molecules can be controlled, with significant intellectual tension between mechanical and chemical ways of thinking about and describing molecular machines. A thermodynamically consistent analysis of the kinetics of several molecular rotors and pumps shows that while light driven rotors operate by a power-stroke mechanism, kinetic asymmetry-the relative heights of energy barriers-is the sole determinant of the directionality of catalysis driven machines. Power-strokes-the relative depths of energy wells-play no role whatsoever in determining the sign of the directionality. These results, elaborated using trajectory thermodynamics and the nonequilibrium pump equality, show that kinetic asymmetry governs the response of many non-equilibrium chemical phenomena.

Guideline for modeling solid-liquid adsorption: Kinetics, isotherm, fixed bed, and thermodynamics

During the years, adsorption has garnered considerable attention being one of the most cost-effective and efficient methods for separating contaminants out of liquid phase. A comprehensive understanding of adsorption mechanisms entails several crucial steps, including adsorbent characterization, batch and column adsorption tests, fitting of predefined kinetic and isotherm models, and meticulous thermodynamic analysis. These combined efforts serve to provide clarity and insights into the intricate workings of adsorption phenomena. However, the vast amount of literature published in the field each year is riddled with ill-considered model selections and incorrect parameter analyses. Therefore, the aim of this paper is to establish guidelines for the proper employment of these numerous kinetic, isotherm, and fixed-bed models in various applications. A thorough review has been undertaken, encompassing more than 45 kinetic models, 70 isotherm models, and 45 fixed bed models available hitherto, with their classification determined based on the adsorption mechanisms expounded within each of them. Moreover, five general approaches for modifying fixed-bed models were provided. The physical meanings, assumptions, and interconversion relationships of the models were discussed in detail, along with the information criterion used to evaluate their validity. In addition to commonly used activation energy and Gibbs energy analysis, the methods for calculating site energy distribution were also summarized.

Ratcheting synthesis

Synthetic chemistry has traditionally relied on reactions between reactants of high chemical potential and transformations that proceed energetically downhill to either a global or local minimum (thermodynamic or kinetic control). Catalysts can be used to manipulate kinetic control, lowering activation energies to influence reaction outcomes. However, such chemistry is still constrained by the shape of one-dimensional reaction coordinates. Coupling synthesis to an orthogonal energy input can allow ratcheting of chemical reaction outcomes, reminiscent of the ways that molecular machines ratchet random thermal motion to bias conformational dynamics. This fundamentally distinct approach to synthesis allows multi-dimensional potential energy surfaces to be navigated, enabling reaction outcomes that cannot be achieved under conventional kinetic or thermodynamic control. In this Review, we discuss how ratcheted synthesis is ubiquitous throughout biology and consider how chemists might harness ratchet mechanisms to accelerate catalysis, drive chemical reactions uphill and programme complex reaction sequences.

Switched "On" Transient Fluorescence Output from a Pulsed-Fuel Molecular Ratchet

We report the synthesis and operation of a molecular energy ratchet that transports a crown ether from solution onto a thread, along the axle, over a fluorophore, and off the other end of the thread back into bulk solution, all in response to a single pulse of a chemical fuel (CCl3CO2H). The fluorophore is a pyrene residue whose fluorescence is normally prevented by photoinduced electron transfer (PET) to a nearby N-methyltriazolium group. However, crown ether binding to the N-methyltriazolium site inhibits the PET, switching on pyrene fluorescence under UV irradiation. Each pulse of fuel results in a single ratchet cycle of transient fluorescence (encompassing threading, transport to the N-methyltriazolium site, and then dethreading), with the onset of the fluorescent time period determined by the amount of fuel in each pulse and the end-point determined by the concentration of the reagents for the disulfide exchange reaction. The system provides a potential alternative signaling approach for artificial molecular machines that read symbols from sequence-encoded molecular tapes.

Bipolar Molecular Torque Wrench Modulates the Stacking of Two-Dimensional Metal-Organic Framework Nanosheets

The precise modulation of nanosheet stacking modes introduces unforeseen properties and creates momentous applications but remains a challenge. Herein, we proposed a strategy using bipolar molecules as torque wrenches to control the stacking modes of 2-D Zr-1,3,5-(4-carboxylphenyl)-benzene metal-organic framework (2-D Zr-BTB MOF) nanosheets. The bipolar phenyl-alkanes, phenylmethane (P-C1) and phenyl ethane (P-C2), predominantly instigated the rotational stacking of Zr-BTB-P-C1 and Zr-BTB-P-C2, displaying a wide angular distribution. This included Zr-BTB-P-C1 orientations at 0, 12, 18, and 24° and Zr-BTB-P-C2 orientations at 0, 6, 12, 15, 24, and 30°. With reduced polarity, phenyl propane (P-C3) and phenyl pentane (P-C5) introduced steric hindrance and facilitated alkyl hydrophobic interactions with the nanosheets, primarily resulting in the modulation of eclipsed stacking for Zr-BTB-P-C3 (64.8%) and Zr-BTB-P-C5 (93.3%) nanosheets. The precise angle distributions of four Zr-BTB-P species were in agreement with theoretical calculations. The alkyl induction mechanism was confirmed by the sequential guest replacement and 2-D 13C-1H heteronuclear correlation (HETCOR). In addition, at the single-particle level, we first observed that rotational stacked pores exhibited similar desorption rates for xylene isomers, while eclipsed stacked pores showed significant discrepancy for xylenes. Moreover, the eclipsed nanosheets as stationary phases exhibited high resolution, selectivity, repeatability, and durability for isomer separation. The universality was proven by another series of bipolar acetate-alkanes. This bipolar molecular torque wrench strategy provides an opportunity to precisely control the stacking modes of porous nanosheets.

Artificial Molecular Ratchets: Tools Enabling Endergonic Processes

Non-equilibrium chemical systems underpin multiple domains of contemporary interest, including supramolecular chemistry, molecular machines, systems chemistry, prebiotic chemistry, and energy transduction. Experimental chemists are now pioneering the realization of artificial systems that can harvest energy away from equilibrium. In this tutorial Review, we provide an overview of artificial molecular ratchets: the chemical mechanisms enabling energy absorption from the environment. By focusing on the mechanism type-rather than the application domain or energy source-we offer a unifying picture of seemingly disparate phenomena, which we hope will foster progress in this fascinating domain of science.

Enhancing the Photocatalytic Activity of Zirconium-Based Metal-Organic Frameworks Through the Formation of Mixed-Valence Centers

Despite the desirability of metal-organic frameworks (MOFs) as heterogeneous photocatalysts, current strategies available to enhance the performance of MOF photocatalysts are complicated and expensive. Herein, a simple strategy is presented for improving the activity of MOF photocatalysts by regulating the atomic interface structure of the metal active sites on the MOF. In this study, MOF (PCN-222) is hybridized with cellulose acetate (CA@PCN-222) through an optimized atomic interface strategy, which lowers the average valence state of Zr ions. The electronic metal-support interaction mechanism of CA@PCN-222 is revealed by evaluating the photocatalytic CO2 reduction reaction (CO2 RR). The experimental results suggested that the electron migration efficiency at the atomic interface of the MOFs strongly coupled with cellulose is significantly improved. In particular, the CO2 RR to formate activity of CA@PCN-222 photocatalyst greatly increased from 778.2 to 2816.0 µmol g-1 compared with pristine PCN-222 without cellulose acetate. The findings suggest that the strongly coupled metal-ligand moiety at the atomic interface of MOFs may play a synergistic role in heterogeneous catalysts.

Active Micelle Pumping Channel Triggers Nonequilibrium Surface Excess Aggregation

Adsorbate transport during the electrochemical process mostly follows the electric-field direction or the high-to-low direction along the concentration gradient and thus often limits the reactant concentration at the adsorption site and requires specific mechanical or chemical bonds of adsorbates to trigger local excess aggregation for advanced framework structure assembly. Herein, we have discovered an active pumping channel during electrochemical adsorption of a manganese colloid, which follows a low-to-high direction inverse concentration gradient. It triggers surface excess micelle aggregation with even over 16-folds higher concentration than that in bulk owing to hydrogen-bonding difference of the micelle surface between in bulk and at the water surface. Micelles in the channel exhibit unique polymerization behaviors by directly polymerizing monomer micelles to form highly catalytic MnO2 of dendritic frameworks, which can serve as a scalable thin-layer aqueous-phase reactor. It increases the understanding of the interface-dependent dynamic nature of micelle or more adsorbates and inspires transformative synthesizing approaches for advanced oxide materials.

Controlling Intramolecular and Intermolecular Electronic Coupling of Radical Ligands in a Series of Cobaltoviologen Complexes

Controlling electronic coupling between multiple redox sites is of interest for tuning the electronic properties of molecules and materials. While classic mixed-valence (MV) systems are highly tunable, e.g., via the organic bridges connecting the redox sites, metal-bridged MV systems are difficult to control because the electronics of the metal cannot usually be altered independently of redox-active moieties embedded in its ligands. Herein, this limitation was overcome by varying the donor strengths of ancillary ligands in a series of cobalt complexes without directly perturbing the electronics of viologen-like redox sites bridged by the cobalt ions. The cobaltoviologens [1_X-Co]ⁿ⁺ feature four 4-X-pyridyl donor groups (X = CO₂Me, Cl, H, Me, OMe, NMe₂) that provide gradual electronic tuning of the bridging Co^II centers, while a related complex [2-Co]ⁿ⁺ with NHC donors supports exclusively Co^III states even upon reduction of the viologen units. Electrochemistry and IVCT band analysis indicate that the MV states of these complexes have electronic structures ranging from fully localized ([2-Co]⁴⁺; Robin-Day Class I) to fully delocalized ([1_CO2Me-Co]³⁺; Class III) descriptions, demonstrating unprecedented control over electronic coupling without changing the identity of the redox sites or bridging metal. Additionally, single-crystal XRD characterization of the homovalent complexes [1_H-Co]²⁺ and [1_H-Zn]²⁺ revealed radical-pairing interactions between the viologen ligands of adjacent complexes, representing a type of through-space electronic coupling commonly observed for organic viologen radicals but never before seen in metalloviologens. The extended solid-state packing of these complexes produces 3D networks of radical π-stacking interactions that impart unexpected mechanical flexibility to these crystals.

Functional dynamics in framework materials

Dynamic crystalline materials have emerged as a unique category of condensed phase matter that combines crystalline lattice with components that display dynamic behavior in the solid state. This has involved a range of materials incorporating dynamic functional units in the form of stimuli-responsive molecular switches and machines, among others. In particular, it has been possible by relying on framework materials, such as porous molecular frameworks and other hybrid organic-inorganic systems that demonstrated potential for serving as scaffolds for dynamic molecular functions. As functional dynamics increase the level of complexity, the associated phenomena are often overlooked and need to be explored. In this perspective, we discuss a selection of recent developments of dynamic solid-state materials across material classes, outlining opportunities and fundamental and methodological challenges for their advancement toward innovative functionality and applications.

Light-responsive rotaxane-based materials: inducing motion in the solid state

Light-responsive rotaxane-based solid-state materials are ideal scaffolds in order to develop smart materials due to the properties provided by the mechanical bond, such as control over the dynamics of the components upon application of external stimuli. This perspective aims to highlight the relevance of these materials, by pointing out recent examples of photoresponsive materials prepared from a rotaxanated architecture in which motion of the counterparts and/or macroscopic motion of the interlocked materials are achieved. Although further development is needed, these materials are envisioned as privileged scaffolds which will be used for different advanced applications in the area of molecular machinery.

Silane-Functionalized Metal-Organic Frameworks for Stimuli-Responsive Drug Delivery Systems: A New Universal Strategy

A new universal strategy for silane functionalization of metal-organic frameworks (MOFs) was developed. It was demonstrated that silanes were coupled both with terminal hydroxyl (OH) groups and with bridging OH groups of metal-oxo clusters of MOFs through condensation reactions between the silanols of hydrolyzed silanes and the terminal/bridging OH groups to form metal-O-Si bonds. A wide variety of functionalization of MOFs with conventional silanes can be realized by combining synthesis reactions in the solution phase and chemical modifications on the surface. Multivalent supramolecular nanovalves based on the host-guest chemistry of cyclodextrin polymer (CDP) and benzimidazole stalks silanized on the nanoscale MOF (NMOF) surface were successfully constructed. The CDP-valved NMOFs showed the excellent performance of low pH- and α-amylase-responsive controlled drug release. In vitro and in vivo results demonstrated that the CDP-valved NMOFs had a significant inhibitory effect on tumor growth and almost no damage/toxicity to normal tissues. The silanization strategy is universal and opens up a new way for the functionalization of MOFs, which are endowed with a wide variety of applications spanning gas storage, chemical sensing, adsorption and separation, heterogeneous catalysis, and drug delivery.

Photoactivated Artificial Molecular Motors

Accurate control of long-range motion at the molecular scale holds great potential for the development of ground-breaking applications in energy storage and bionanotechnology. The past decade has seen tremendous development in this area, with a focus on the directional operation away from thermal equilibrium, giving rise to tailored man-made molecular motors. As light is a highly tunable, controllable, clean, and renewable source of energy, photochemical processes are appealing to activate molecular motors. Nonetheless, the successful operation of molecular motors fueled by light is a highly challenging task, which requires a judicious coupling of thermal and photoinduced reactions. In this paper, we focus on the key aspects of light-driven artificial molecular motors with the aid of recent examples. A critical assessment of the criteria for the design, operation, and technological potential of such systems is provided, along with a perspective view on future advances in this exciting research area.

Sequential Modifications of Metal-Organic Layer Nodes for Highly Efficient Photocatalyzed Hydrogen Atom Transfer

Herein, we report the synthesis of a bifunctional photocatalyst, Zr-OTf-EY, through sequential modifications of metal cluster nodes in a metal-organic layer (MOL). With eosin Y and strong Lewis acids on the nodes, Zr-OTf-EY catalyzes cross-coupling reactions between various C-H compounds and electron-deficient alkenes or azodicarboxylate to afford C-C and C-N coupling products, with turnover numbers of up to 1980. In Zr-OTf-EY-catalyzed reactions, Lewis acid sites bind the alkenes or azodicarboxylate to increase their local concentrations and electron deficiency for enhanced radical additions, while EY is stabilized by site isolation on the MOL to afford a long-lived catalyst for hydrogen atom transfer. The proximity between photostable EY sites and Lewis acids on the nodes of Zr-OTf-EY enhances the catalytic efficiency by approximately 400 times over the homogeneous counterpart in the cross-coupling reactions.

Active Separation of Water Isotopologues by Local Molecular Motion in Microporous Framework Materials

Around 10-15 % of the world's energy consumption is accounted for by the separation and purification of chemicals. Among them is the enrichment and separation of isotopologues which are an essential aspect of modern chemistry. In their recent work, Su et al. demonstrate the separation of water isotopologues by responsive dynamic pore windows in a microporous coordination polymer with unprecedented selectivity based on an elegant mechanism.

Formation of Direction-Controllable Pseudorotaxane and Catenane Using Chemically Cyclized Oligodeoxynucleotides and Their Noncovalent RNA Labeling

The formation of interlocked structures, such as rotaxane and catenane, enables noncovalent conjugations. We previously confirmed that the chemically cyclized pseudorotaxane-forming oligodeoxynucleotides (prfODNs) with double-tailed parts formed a pseudorotaxane structure with the target DNA and RNA via the slipping process. Here, we report the one-step synthesis of cyclized prfODNs from alkyne-modified ODNs, after which we investigated the properties and mechanism of the slipping process and performed noncovalent RNA labeling with prfODNs. Additionally, the catenane structure was formed by the combination of pseudorotaxane formation with a 5'-end-phosphorylated RNA and enzymatic ligation. The newly synthesized prfODN represents a new tool for achieving the noncovalent conjugation of various functional moieties to RNAs.

Kinetic Asymmetry versus Dissipation in the Evolution of Chemical Systems as Exemplified by Single Enzyme Chemotaxis

Single enzyme chemotaxis is a phenomenon by which a nonequilibrium spatial distribution of an enzyme is created and maintained by concentration gradients of the substrate and product of the catalyzed reaction. These gradients can arise either naturally through metabolism or experimentally, e.g., by flow of materials through microfluidic channels or by use of diffusion chambers with semipermeable membranes. Numerous hypotheses regarding the mechanism of this phenomenon have been proposed. Here, we discuss a mechanism based solely on diffusion and chemical reaction and show that kinetic asymmetry, a difference in the transition state energies for dissociation/association of substrate and product, and diffusion asymmetry, a difference in the diffusivities of the bound and free forms of the enzyme, are the determinates of the direction of chemotaxis and can result in either positive or negative chemotaxis, both of which have been demonstrated experimentally. Exploration of these fundamental symmetries that govern nonequilibrium behavior helps to distinguish between possible mechanisms for the evolution of a chemical system from initial to the steady state and whether the principle that determines the direction a system shifts when exposed to an external energy source is based on thermodynamics or on kinetics with the latter being supported by the results of the present paper. Our results show that, while dissipation ineluctably accompanies nonequilibrium phenomena, including chemotaxis, systems do not evolve to maximize or minimize dissipation but rather to attain greater kinetic stability and accumulate in regions where their effective diffusion coefficient is as small as possible. The chemotactic response to the chemical gradients formed by other enzymes participating in a catalytic cascade provides a mechanism for forming loose associations known as metabolons. Significantly, the direction of the effective force due to these gradients depends on the kinetic asymmetry of the enzyme and so can be nonreciprocal, where one enzyme is attracted to another enzyme, but the other enzyme is repelled by the one, in seeming contradiction to Newtons third law. This nonreciprocity is an important ingredient in the behavior of active matter.

Triggered Polymersome Fusion

The contents of biological cells are retained within compartments formed of phospholipid membranes. The movement of material within and between cells is often mediated by the fusion of phospholipid membranes, which allows mixing of contents or excretion of material into the surrounding environment. Biological membrane fusion is a highly regulated process that is catalyzed by proteins and often triggered by cellular signaling. In contrast, the controlled fusion of polymer-based membranes is largely unexplored, despite the potential application of this process in nanomedicine, smart materials, and reagent trafficking. Here, we demonstrate triggered polymersome fusion. Out-of-equilibrium polymersomes were formed by ring-opening metathesis polymerization-induced self-assembly and persist until a specific chemical signal (pH change) triggers their fusion. Characterization of polymersomes was performed by a variety of techniques, including dynamic light scattering, dry-state/cryogenic-transmission electron microscopy, and small-angle X-ray scattering (SAXS). The fusion process was followed by time-resolved SAXS analysis. Developing elementary methods of communication between polymersomes, such as fusion, will prove essential for emulating life-like behaviors in synthetic nanotechnology.

Natural phenol-inspired porous polymers for efficient removal of tetracycline: Experimental and engineering analysis

Efficient and feasible removal of trace antibiotics from wastewater is extremely important due to its environmental persistence, bioaccumulation, and toxicity, but still remains a huge challenge. Herein, three natural phenol-inspired porous organic polymers were fabricated from natural phenolic-derived monomers (p-hydroxy benzaldehyde, 2,4-dihydroxy benzaldehyde and 2,4,6-trihydroxy benzaldehyde) and melamine via polycondensation reaction. Characterization highlighted that the increasing contents of hydroxyl groups in monomers induced an increase of the polymer total porosity and promoted the formation of a highly microporous structure. With mesopore-dominated pore (average pore diameter 9.6 nm) and large pore volume (1.78 cm³/g), p-hydroxy benzaldehyde-based porous polymer (1-HBPP) exhibited ultra-high maximum adsorption capacity (q_max) of 697.6 mg/g for tetracycline (TC) antibiotic. Meanwhile, the porous networks and plentiful active sites of 1-HBPP enabled fast adsorption kinetics (within 10 min) for TC removal, which could be well described by the pseudo-second-order model. Dynamic adsorption studies showed that 1-HBPP could be used in fixed-bed adsorption column (FBAC) with high removal efficiency (breakthrough volume per unit mass, 13.2 L/g) and dynamic adsorption capacity (201.6 mg/g), which were much higher than other reported adsorbents. The breakthrough curves both well matched with Thomas and Yoon-Nelson models in FBAC treatment. Moreover, removal mechanism analysis affirmed that pore-filling, hydrogen bonding, electrostatic interactions and π-π stacking interactions were main driving forces for TC adsorption. The prepared natural phenol-inspired porous adsorbents show great potential in antibiotics removal from wastewater, and this strategy would promote the sustainable and high-value utilization of natural phenolic compounds.

Recent Advances in the Preparation of Delivery Systems for the Controlled Release of Scents

Scents are volatile compounds highly employed in a wide range of manufactured items, such as fine perfumery, household products, and functional foods. One of the main directions of the research in this area aims to enhance the longevity of scents by designing efficient delivery systems to control the release rate of these volatile molecules and also increase their stability. Several approaches to release scents in a controlled manner have been developed in recent years. Thus, different controlled release systems have been prepared, including polymers, metal-organic frameworks and mechanically interlocked systems, among others. This review is focused on the preparation of different scaffolds to accomplish a slow release of scents, by pointing out examples reported in the last five years. In addition to discuss selected examples, a critical perspective on the state of the art of this research field is provided, comparing the different types of scent delivery systems.

Molecular Engineering of Metal-Organic Layers for Sustainable Tandem and Synergistic Photocatalysis

Metal-organic layers (MOLs), a monolayered version of metal-organic frameworks (MOFs), have recently emerged as a novel two-dimensional molecular material platform to design multifunctional catalysts. MOLs inherit the intrinsic molecular tunability of MOFs and yet have more accessible and modifiable building blocks. Here we report molecular engineering of six MOLs via modulated solvothermal synthesis between HfCl4 and three photosensitizing ligands followed by postsynthetic modification with two carboxylate-containing cobaloximes for tandem and synergistic photocatalysis. Morphological and structural characterization by transmission electron microscopy and atomic force microscopy and compositional analysis by inductively coupled plasma-mass spectrometry and nuclear magnetic resonance spectroscopy establish the MOLs as flat nanoplates with a periodic lattice structure of hexagonal symmetry. The MOLs efficiently catalyze tandem dehydrogenative coupling reactions and synergistic Heck-type coupling reactions. The most active MOL catalyst was used for the gram-scale synthesis of vesnarinone, a cardiotonic agent, in 80% yield with a turnover number of 400 and in eight consecutive reaction cycles without significant loss of activities.