A host-guest semibiological photosynthesis system coupling artificial and natural enzymes for solar alcohol splitting

Design and Synthesis of a Cluster-Based Supramolecular Reaction Pump for the Efficient Catalysis of Amination Reactions

Although discrete self-assembled cage compounds with single-metal centers mimicking natural bioreactors for catalysis have been extensively investigated, studies on those with multimetal active centers, i.e., cluster active centers (CACs), have been less explored. Herein, we present the design and synthesis of a novel cluster-based supramolecular reaction pump (CSRP-1) featuring four CACs that facilitate catalysis. CSRP-1 holds a cationic supramolecular tetrahedral structure, comprising four WS3Cu3 clusters, each positioned at one vertex and interconnected by dipyridyl linkers. Substrates, including aryl iodides or primary or secondary amines, enter the cage cavity by replacing N,N-dimethylformamide at the CACs through weak Cu···I/N interactions. This design leverages the coordinatively unsaturated Cu centers within each CAC to activate the substrates, resulting in efficient catalytic amination. CSRP-1 works like a dynamic pump, and upon completion of the reaction, the amine product is expelled from the cavity, allowing the catalytic cycle to repeat with maintained efficiency. Theoretical calculations complement the experimental findings, providing key insights into the catalytic mechanism and the synergistic role of the clusters and linkers. This work offers a new catalysis paradigm with broad applicability to various organic reactions.

Selective Aliphatic Aldimine Formation and Stabilization by a Hydrophobic Capsule in Water

Imines and enamines are useful intermediates in biochemical aldol-type reactions since their acid/base characteristics are accessible near neutrality. However, the generation of aldimines in water is a challenge as the equilibrium favors the components alkyl amines and aldehydes. Here, we report the generation, recognition, and protection of aldimines accomplished by a water-soluble capsule. The capsule provides a well-defined hydrophobic cavity isolating aldimines from the medium by a dry seam of Se-N chalcogen bonds instead of a wet seam of hydrogen bonds in water. A series of diverse aldimines are formed in situ and trapped rapidly (within 45 min at mM concentrations) in D2O with more than 90% yields. The encapsulated aldimines are stable for at least one month under ambient conditions. The aliphatic aldimines are selectively formed in the capsule even though they are less stable than aromatic imines in solution. The aldimines can be released from the capsule containers by competitive guests such as adamantane.

Unveiling the genetic networks: Exploring the dynamic interaction of photosynthetic phenotypes in woody plants across varied light gradients

Understanding the mechanisms by which genes control and regulate complex quantitative traits during periods of fluctuating resources remains a challenging and uncertain task in photosynthesis studies. Most studies have focused on the structure of photosynthesis, the photosynthetic response under stress, or the genetic mechanisms involved in photosynthetic effects and neglected the interactive genetic mechanism that governs various traits through significant quantitative trait loci (QTLs). In this study, we have developed a differential dynamic system that enables the identification of QTLs based on the photosynthetic phenotypic and genotypic data under varying levels of light intensity gradients. The framework not only allows for the assessment of the direct effects of QTLs on phenotypes but also captures how they influence interactions among phenotypes as light intensities change. We have analyzed the genetic effects and genetic variance, visualized the genetic network associated with photosynthesis interactions, and validated the effectiveness and stability of the DDS framework. Pivotal pleiotropic QTLs were identified individually to uncover the process and pattern of interaction. Through functional annotation, we made an intriguing discovery that seemingly unimportant QTLs can still have significant genetic effects on phenotypic changes through their regulation with other QTLs. This finding emphasizes the significance of considering the interactive genetic architecture when seeking to understand the genetic interaction mechanism of photosynthesis in natural populations of woody plants. Moreover, our research provides a novel framework that can be extended to explore the interactive genetic architecture among organisms, contributing to a deeper understanding of stress resistance mechanisms in woody plants.

Paramagnetic Cage-Type Co(II) Complexes of Chiral Macrocycles: Enantio- and Size-Selective Binding of Guest Molecules

Two enantiomers of the cage-type complex, [Co3LR2] and [Co3LS2] of a large hexaazatriphenolic [3 + 3] macrocyclic imine L, have been synthesized and characterized on the basis of NMR, CD, and ESI MS spectra. The X-ray crystal structures of [Co3L2] crystalline forms reveal two macrocycles of cone shape stitched together by three Co(II) ions, forming a barrel-shaped molecule with a central void. Because of the limited size of the [Co3L2] cavity and the enantiopure nature of these enantiomeric complexes, both size-selective and enantioselective binding of guest molecules are observed. In the case of chiral guests, the interaction with paramagnetic Co(II) centers leads to an effective NMR enantiodifferentiation of the signals of guest molecules, even at host:guest ratios as low as 1:200. The tight binding of prochiral guest molecules such as ethanol and isopropanol within the chiral cavity results in the splitting of enantiotopic methylene and methyl signals. The dc magnetic data for [Co3L2] are in accord with the presence of high-spin Co(II) ions, and the ac susceptibility data of this complex indicate field-induced single molecule magnet (SMM) behavior. In contrast to the reaction with Co(II), the reaction of the macrocyclic ligand H3L with Ni(II) or Cu(II) salts results in the contraction of this [3 + 3] macrocycle and the formation of complexes of a smaller [2 + 2] macrocycle.

Isolation of a copper photocatalyst on a metal-organic cage for the sulfonylation of aryl halides resulting from visible-light-mediated C(sp2)-S cross-coupling

A Ce-based metal-organic tetrahedron was assembled for preserving the uncoordinated nature of 2,2'-bipyridyl groups to form a Cu-based photocatalyst, which protected CuI centers from intermolecular deactivation and showed high photocatalytic activity for the visible-light-mediated C(sp²)-S cross-coupling.

Redox Triggers Guest Release and Uptake Across a Series of Azopyridine-Based Metal-Organic Capsules

Precise control over guest release and recapture using external stimuli is a valuable goal, potentially enabling new modes of chemical purification. Including redox moieties within the ligand cores of molecular capsules to trigger the release and uptake of guests has proved effective, but this technique is limited to certain capsules and guests. Herein, the construction of a series of novel metal-organic capsules from ditopic, tritopic, and tetratopic ligands is demonstrated, all of which contain redox-active azo groups coordinated to FeII centers. Compared to their iminopyridine-based analogs, this new class of azopyridine-based capsules possesses larger cavities, capable of encapsulating more voluminous guests. Upon reduction of the capsules, their guests are released and may then be re-encapsulated when the capsules are regenerated by oxidation. Since the redox centers are on the ligand arms, they are modular and can be attached to a variety of ligand cores to afford varying and predictable architectures. This method thus shows promise as a generalized approach for designing redox-controlled guest release and uptake systems.

Separation of mercuric ions using 2-thienylbenzimidazole/cucurbit[7]uril/iron-oxide nanoparticles by pH control

2-Thienylbenzimidazole (TBI)/cucurbit[7]uril (CB7) host-guest complex was used as a motif to significantly improve the turnover of γ-Fe₃O₄ magnetic nanoparticles for potential application in the separation of toxic mercuric ions in polluted water samples. The mechanism of restoring the original solid materials is based on applying the pH-controlled preferential binding of the CB7 host to the TBI guest. The analytical application of this concept has not been realized in the literature. The pH-controlled stimuli-responsive abilities were confirmed in aqueous solution by the three-order of magnitudes higher stability constant of the protonated TBIH⁺/CB7 complex (e.g., K = 4.8 × 10⁸ M^-1) when compared to neutral TBI/CB7 complex (e.g., K = 2.4 × 10⁵ M^-1), also manifested in an increase in pK_a values by ~ 3.3 units in the ground state. The supramolecular interaction and adsorption on iron oxide nanoparticles (NPs) were also spectroscopically confirmed in the solid state. The excited-state lifetime values of TBI/CB7NPs increased upon lowering the pH values (e.g., from 0.6 to 1.3 ns) with a concomitant blue shift of ~ 25 nm because of polarity effects. The time-resolved photoluminescent behaviors of the final solids in the presence of CB7 ensured pH-driven reusable systems for capturing toxic mercuric ions. The study offers a unique approach for the controllable separation of mercury ions using an external magnet and in response to pH through preferential binding of the host to guest molecules on the top of magnetic surfaces.

Electric double layer-mediated polarization field for optimizing photogenerated carrier dynamics and thermodynamics

Photocatalytic hydrogen evolution efficiency is limited due to unfavorable carrier dynamics and thermodynamic performance. Here, we propose to introduce electronegative molecules to build an electric double layer (EDL) to generate a polarization field instead of the traditional built-in electric field to improve carrier dynamics, and optimize the thermodynamics by regulating the chemical coordination of surface atoms. Based on theoretical simulation, we designed CuNi@EDL and applied it as the cocatalyst of semiconductor photocatalysts, finally achieved a hydrogen evolution rate of 249.6 mmol h^-1 g^-1 and remained stable after storing under environmental conditions for more than 300 days. The high H₂ yield is mainly due to the perfect work function, Fermi level and Gibbs free energy of hydrogen adsorption, improved light absorption ability, enhanced electron transfer dynamics, decreased HER overpotential and effective carrier transfer channel arose by EDL. Here, our work opens up new perspectives for the design and optimization of photosystems.

Enzyme Grafting with a Cofactor-Decorated Metal-Organic Capsule for Solar-to-Chemical Conversion

Semi-artificial approaches to solar-to-chemical conversion can achieve chemical transformations that are beyond the capability of natural enzymes, but face marked challenges to facilitate in vivo cascades, due to their inevitable need for cofactor shuttling and regeneration. Here, we report on an enzyme grafting strategy to build a metal-organic capsule-docking artificial enzyme (metal-organic-enzyme, MOE) that comprised the self-assembly of a cofactor-decorated capsule and the supramolecular enzyme-recognition features between the enzyme scaffold and the capsule to bypass cofactor shuttling and regeneration. The incorporated NADH mimics within the metal-organic capsule interacted with the imine intermediate that formed from the condensation of the amines and the dehydrogenation of alcohol substrates in the microenvironment to form complexes within the capsule and subsequently served as an in situ-generated photoresponsive cofactor. Upon illumination, the photoresponsive cofactor facilitates efficient proton/electron transport between the inner space (supramolecular hydrogenation) and outer space (enzymatic dehydrogenation) of the capsule to dehydrogenize the alcohols and hydrogenize the imine intermediates, respectively, circumventing the conventionally complex multistep cofactor shuttling and regeneration. The semi-artificial enzyme endows the conversion of diverse types of alcohol to amine products in both aqueous/organic solutions and Escherichia coli with high efficiency, offering a wide range of opportunities for sustainable and environmentally friendly biomanufacturing of commodity and fine chemicals.

Air-Stable Radical Organic Cages as Cascade Nanozymes for Enhanced Catalysis

The pursuit of single-assembled molecular cage reactors for complex tandem reactions is a long-standing target in biomimetic catalysis but still a grand challenge. Herein, nanozyme-like organic cages are reported by engineering air-stable radicals into the skeleton upon photoinduced electron transfer. The generation of radicals is accompanied by single-crystal structural transformation and exhibits superior stability over six months in air. Impressively, the radicals throughout the cage skeleton can mimic the peroxidase of natural enzymes to decompose H₂ O₂ into OH· and facilitate oxidation reactions. Furthermore, an integrated catalyst by encapsulating Au clusters (glucose oxidase mimics) into the cage has been developed, in which the dual active sites (Au cluster and radical) are spatially isolated and can work as cascade nanozymes to prominently promote the enzyme-like tandem reaction via a substrate channeling effect.

Artificial photosynthesis systems for solar energy conversion and storage: platforms and their realities

In natural photosynthesis, photosynthetic organisms such as green plants realize efficient solar energy conversion and storage by integrating photosynthetic components on the thylakoid membrane of chloroplasts. Inspired by natural photosynthesis, researchers have developed many artificial photosynthesis systems (APS's) that integrate various photocatalysts and biocatalysts to convert and store solar energy in the fields of resource, environment, food, and energy. To improve the system efficiency and reduce the operation cost, reaction platforms are introduced in APS's since they allow for great stability and continuous processing. A systematic understanding of how a reaction platform affects the performance of artificial photosynthesis is conducive for designing an APS with superb solar energy utilization. In this review, we discuss the recent APS's researches, especially those confined on/in platforms. The importance of different platforms and their influences on APS's performance are emphasized. Generally, confined platforms can enhance the stability and repeatability of both photocatalysts and biocatalysts in APS's as well as improve the photosynthetic performance due to the proximity effect. For functional platforms that can participate in the artificial photosynthesis reactions as active parts, a high integration of APS's components on/in these platforms can lead to efficient electron transfer, enhanced light-harvesting, or synergistic catalysis, resulting in superior photosynthesis performance. Therefore, the integration of APS's components is beneficial for the transfer of substrates and photoexcited electrons in artificial photosynthesis. We finally summarize the current challenges of APS's development and further efforts on the improvement of APS's.

Binding of Dual-Function Hybridized MetalOrganic Capsules to Enzymes for Cascade Catalysis

The combination of chemo- and biocatalysis for multistep syntheses provides attractive advantages in terms of evolvability, promiscuity, and sustainability striving for desirable catalytic performance. Through the encapsulation of flavin analogues by both NADH and heme mimics codecorated heteroleptic metal-organic capsules, herein, we report a progressive host-guest strategy to imitate cytochrome P450s catalysis for cascade oxidative coupling catalysis. Besides the construction of stable dual-function metal-organic capsules and the modification of cofactor-decorated capsules at the domain of enzymes, this supramolecular strategy involves multistage directional electron flow, affording reactive ferric peroxide species for inducing oxygenation. Under light irradiation, the metal-organic capsule selectively converts stilbene to oxidative coupling products (including 2-oxo-1,2-diphenylethyl formate, 2-alkoxy-1,2-diphenylethanone) in tandem with enzymatic reactions respectively, at the domain of natural enzymes. The ingenious combination of capsules and enzymes with the in situ-regenerated capsule-loaded NADH cofactor promises non-native coupling reactions by forming regional cooperation and division. This abiotic-biotic conjugated host-guest strategy is conducive to the de novo creation of multifunctional components approaching active enzymatic sites for reinforced matter and energy transporting, demonstrating a key role of multicomponent supramolecular catalysts for one-pot integrated catalytic conversions.

An electron-deficient MOF as an efficient electron-transfer catalyst for selective oxidative carbon-carbon coupling of 2,6-di-tert-butylphenol

Naphthalene diimides (NDIs), a type of electron-deficient dye molecule with high quadrupole moment and excellent redox activity, have been utilized in various fields, such as energy transfer, chemical sensing, anion transport, and photo-/electrochromic materials. In this study, an electron-deficient metal-organic framework with one-dimensional channels, Eu₂(BBNDI)₃(DMF)₂ (MOF 1) (H₂BBNDI = N,N'-bis(3-benzoic acid)naphthalene diimide), was successfully constructed based on the naphthalene diimide derivative. Because of the generation of NDI radicals by electron transfer between components, this material exhibits fast-responsive reversible photochromic properties. Moreover, it shows high efficiency and selective oxidation of 2,6-di-tert-butylphenol to its quinone derivative, aldehyde, and dimeric or trimeric phenol derivative by controlling the reaction conditions.

Photoactive perylenediimide metal–organic framework for boosting iodoperfluoroalkylation of alkenes and oxidative coupling of amines

A novel photoactive MOF was prepared based on an electron-deficient perylenediimide derivative, which exhibits excellent photocatalytic activities towards the iodoperfluoroalkylation of alkenes and the oxidation of amines to imines.