Cation-π interaction: its role and relevance in chemistry, biology, and material science

Biomimetic Parallel Vein-like Two-Dimensional Supramolecular Layers Containing Embedded One-Dimensional Conduits Driven by Cation-π Interaction and Hydrogen Bonding to Promote Photocatalytic Hydrogen Evolution

Two-dimensional supramolecular assemblies (2DSAs) with well-defined nanostructures have emerged as promising candidates for diverse applications, particularly in photocatalysis. However, it still remains a significant challenge to simultaneously achieve effective electron transport and multiple active sites in 2DSA, even though this is crucial for enhancing photocatalytic performance. This reason can be attributed to the lack of a suitable structural paradigm that enables both effective intermolecular orbital overlap and increased substrate contact. Inspired by the parallel venation of monocotyledons that can facilitate substrate transfer, we overcome the limitation, in this study, by integrating parallel-arranged one-dimensional (1D) conduits with edge-on packing motifs to construct biomimetic, parallel vein-like two-dimensional supramolecular layers (PV-2DSLs) through the hierarchical self-assembly of cationically modified, rigid multiarmed monomers. The resulting PV-2DSLs exhibit a long-range aromatic cation-π stacking that can facilitate electron transport. Importantly, the unique structural feature of these PV-2DSLs is the orderly and parallel embedding of 1D conduits within the 2D plane, which is significantly different from the conventional channels formed by the vertical stacking of 2D porous materials. These conduits promote multielectron transfer pathways, leading to enhanced charge separation and carrier transport when coupled with long-range aromatic cation-π stacking. As a consequence, these PV-2DSLs exhibit long excited state lifetime, leading to significantly improved hydrogen production rates up to 3.5 mmol g-1 h-1, which is approximately 17.5 times higher than that of the counterpart without 1D conduits (0.2 mmol g-1 h-1).

Insights into the Direct Photoelectron Transfer Mechanism in Cofactor-free Redox Carbon Dots and Cytochrome c Nitrite Reductase Biohybrids Responsible for Ammonia Synthesis

Highly efficient NH3 production has been reported to be achieved by photosensitizing Shewanella oneidensis MR-1 using carbon dots (CDs). During this process, cytochrome c nitrite reductase (NrfA) is regarded as the rate-limiting enzyme. However, the precise electron transfer mechanism between CDs and NrfA remains unclear. Herein, a hybrid photosynthetic system composed of NrfA and redox CDs (NrfA/R-CDs) was constructed, achieving a maximum NH3 production rate of 12.5 ± 1.1 μmol (NH3)·mg-1 (NrfA)·h-1. R-CDs with aromatic ketone groups could store photoinduced electrons, enhancing carrier separation efficiency. These stored photoelectrons were capable of being directly transferred to NrfA without the need of cofactors. Even under dark conditions, direct electron transfer occurred from the stored photoelectrons in R-CDs to NrfA, providing an indirect illumination approach to reduce phototoxicity to NrfA. Molecular docking and dynamics simulations demonstrated the formation of a stable complex between the heme 2 region of NrfA and R-CDs. The short distance (10 Å) and π-electronic interactions between R-CDs and heme 2 facilitated the direct electronic transfer process. This study provides a comprehensive understanding of the interfacial photoelectron transfer mechanism and guidelines for constructing nanomaterials with photoelectron storage and release properties.

Discrimination and Translocation of Charged Proteinogenic Amino Acids through a Single-Walled Carbon Nanotube

Nanopore sensing relies on associating the measured current signals with specific features of the target molecules. The diversity of amino acids presents significant challenges in detecting and sequencing peptides and proteins. The hollow and uniform tubular structure of single-walled carbon nanotubes (SWCNTs) makes them ideal candidates for nanopore sensors. Here, we demonstrate by molecular dynamics simulations the discrimination and translocation of charged proteinogenic amino acids through the nanopore sensor formed by inserting a SWCNT into lipid bilayers. Moreover, our analysis suggests that the current blockade is influenced not only by excluded atomic volume but also by noncovalent interactions between amino acids and SWCNT during similar helical translocation. The presence of noncovalent interactions enhances the understanding of current differences in nanopore translocation of molecules with similar excluded atomic volume. This finding provides new perspectives and applications for the optimal design of SWCNT nanopore sensors.

Engineering of peptide assemblies for adaptable protein delivery to achieve efficient intracellular biocatalysis

Efficient intracellular delivery of native proteins remains a big challenge, which greatly hinders the development of protein therapy. Here, we report a generalizable peptide vector that can encapsulate and deliver various proteins to achieve efficient intracellular biocatalysis. The peptide was rationally designed to be cationic amphiphilic peptide that consist of four functional fragments, that is, a hydrophobic domain to promote molecular assembly, an enzyme-cleavable fragment to introduce stimuli-responsibility, several cationic arginine (Arg) residues to enhance cell interaction and transmembrane efficiency, and the cystine (Cys) residues with redox sensitivity to adjust the stability of the peptide/protein complexes as needed. The peptide can co-assemble with proteins to form stable complexes in aqueous solution under mild condition. The complexes enter cell mainly through caveolae- and lipid raft-mediated endocytosis, giving a delivery efficiency of up to ∼97.2 %. They can then achieve efficient lysosomal escape and disassociation to release native proteins inside cells in response to intracellular stimuli. More strikingly, the delivered protein's bioactivity can be well maintained and the two model proteins of β-galactosidase (β-Gal) and horseradish peroxidase (HRP) both showed excellent intracellular biocatalytic activity. The study develops a versatile and adjustable peptide carrier platform for protein delivery and highlights impactful structure-function relationships, providing a new chemical guide for the design and optimization of functional protein nanocarriers.

Comparative structural insights and functional analysis for the distinct unbound states of Human AGO proteins

The four human Argonaute (AGO) proteins, critical in RNA interference and gene regulation, exhibit high sequence and structural similarity but differ functionally. We investigated the underexplored structural relationships of these paralogs through microsecond-scale molecular dynamics simulations. Our findings reveal that AGO proteins adopt similar, yet unsynchronized, open-close states. We observed similar and unique local conformations, interdomain distances and intramolecular interactions. Conformational differences at GW182/ZSWIM8 interaction sites and in catalytic/pseudo-catalytic tetrads were minimal. Tetrads display conserved movements, interacting with distant miRNA binding residues. We pinpointed long common protein subsequences with consistent molecular movement but varying solvent accessibility per AGO. We observed diverse conformational patterns at the post-transcriptional sites of the AGOs, except for AGO4. By combining simulation data with large datasets of experimental structures and AlphaFold's predictions, we identified proteins with genomic and proteomic similarities. Some of the identified proteins operate in the mitosis pathway, sharing mitosis-related interactors and miRNA targets. Additionally, we suggest that AGOs interact with a mitosis initiator, zinc ion, by predicting potential binding sites and detecting structurally similar proteins with the same function. These findings further advance our understanding for the human AGO protein family and their role in central cellular processes.

Anion-π interaction guided switchable TADF and low-temperature phosphorescence in phosphonium salts for multiplexed anti-counterfeiting

Anion-π+ interactions have gained continuous attention in diverse organic aggregates, as they can effectively alter emission behavior. Herein, the anion-π+ interaction is introduced to phosphonium salts, which exhibit tunable thermally activated delayed fluorescence and phosphorescence emission. Intriguingly, the emission spectra evolve from deep-blue to yellow emission by regulation of the anion-π+ interaction strength through varying the anions, such as BF4 -, CF3SO3 -, PF6 -, and NO3, accompanied by adjustable luminescent decay times from milliseconds to several seconds. Notably, bright blue emission with a high photoluminescence quantum yield near 100% is achieved when substituting the iodide ions with larger counter anions. The phosphonium iodide with strong anion-π+ interaction and heavy atom effect shows a high inter-system crossing rate, which inhibits the direct and prompt fluorescence emission. The anion-π+ interaction and twisted structure strongly suppress π-π stacking and afford ultra-high photoluminescence yields. Furthermore, the participation of polar solvent molecules results in the solvation and bathochromic-shift phenomenon of the solid-state phosphonium iodide due to the ionic polarized host-guest structure. This work provides new insights into the anion-π+ interaction in luminescent phosphonium aggregates.

Molecular Balances as Physical Organic Chemistry Tools to Quantify Non-Covalent Interactions

Non-covalent interactions are present in numerous synthetic and biological systems, playing an essential role in vital life processes, such as the stabilization of proteins' structures or reversible binding in substrate-receptor complexes. Their study is relevant but faces challenges due to its inherent weak nature. In this context, molecular balances (MBs) are one of the most efficient physical organic chemistry tools to quantify non-covalent interactions, bringing beneficial knowledge regarding their nature and strength. Herein, we report an overview and critical discussion of recent studies related to various MBs in the quantification of a collection of non-covalent interactions, covering from the well-known aryl • • • aryl and CH • • • aryl interaction to the newest fullerene • • • aryl and chalcogen • • • chalcogen interactions.

The Cation-π Interaction in Chemistry and Biology

The cation-π interaction is an important noncovalent binding force that impacts all areas of chemistry and biology. Extensive computational and gas phase experimental studies have established the potential strength and the essential nature of the interaction. Previous reviews have emphasized studies of model systems and a variety of biological examples. This work includes discussion of those areas but emphasizes other areas that are perhaps less well appreciated. These include the novel cation-π binding ability of alkali metals in water; the application of the cation-π interaction to organic synthesis and chemical biology; cooperative behaviors of multiple cation-π interactions, including adhesive proteins from mussels and similar organisms and the formation and modulation of biomolecular condensates (phase separation); and cation-π interactions involved in recognizing DNA/RNA.

Low-coordinate potassium alkoxide - an efficient trap for arenes: the role of ηn non-covalent bonding in substrate activation for C-H bond metalation

Metalation of bulky tris(2-(piperidin-1-yl-methyl)phenyl)methanol [(C5H10N)CH2C6H4-o]3COH with (Me3Si)2NK in Et2O results in a dimeric potassium alkoxide {[(C5H10N)CH2C6H4-o]3C(μ2-O)K(Et2O)}2 (1). The Et2O molecule can be removed from the K+ coordination sphere affording coordinatively unsaturated alkoxide species which readily traps π-donor molecules. In the presence of excess arene, the reactions result in ηn-π-complexes, retaining in the crystal state a dimeric core {[(C5H10N)CH2C6H4-o]3C(μ2-O)K(ηn-arene)}2 (arene = C6H6 (2), CH3C6H5 (3), C10H8 (4)). With C6H5OMe and C6H5NMe2 molecules containing competing n- and π-donating sites, the reactions proceed differently: the former coordinates to K+ through an oxygen lone pair resulting in {[(C5H10N)CH2C6H4-o]3C(μ2-O)K(κ1-O(Me)C6H5)}2 (5) while for the latter, π-arene interaction turns out to be preferable, yielding {[(C5H10N)CH2C6H4-o]3C(μ2-O)K(η2-C6H5NMe2)}2 (6). The reactions with equimolar amounts of benzene or thiophene afford coordination polymers [{[(C5H10N)CH2C6H4-o]3C(μ2-O)K}2(μ-C6H6)]n (7) and [{[(C5H10N)CH2C6H4-o]3C(μ2-O)K}2(μ-C4H4S)]n (8), in which benzene and thiophene molecules are μ-bridging two K+ ions. The treatment of {[(C5H10N)CH2C6H4-o]3C(μ2-O)K(η2-CH3C6H5))}2 with Me3SiCH2Li or n-BuLi (1.2 eq.) in hexane at 20 °C results in the facile metalation of the Me group of toluene, forming [PhCH2K]n and lithium alkoxide. This model reaction provides a deeper insight into the probable mechanism of metalation of CH bonds under Lochmann-Schlosser superbasic conditions, and the role and the nature of the synergistic effect of two metals. The calculations and QTAIM analysis were performed for 1-8 and model molecules as well.

Binary peptide coacervates as an active model for biomolecular condensates

Biomolecular condensates formed by proteins and nucleic acids are critical for cellular processes. Macromolecule-based coacervate droplets formed by liquid-liquid phase separation serve as synthetic analogues, but are limited by complex compositions and high molecular weights. Recently, short peptides have emerged as an alternative component of coacervates, but tend to form metastable microdroplets that evolve into rigid nanostructures. Here we present programmable coacervates using binary mixtures of diphenylalanine-based short peptides. We show that the presence of different short peptides stabilizes the coacervate phase and prevents the formation of rigid structures, allowing peptide coacervates to be used as stable adaptive compartments. This approach allows fine control of droplet formation and dynamic morphological changes in response to physiological triggers. As compartments, short peptide coacervates sequester hydrophobic molecules and enhance bio-orthogonal catalysis. In addition, the incorporation of coacervates into model synthetic cells enables the design of Boolean logic gates. Our findings highlight the potential of short peptide coacervates for creating adaptive biomimetic systems and provide insight into the principles of phase separation in biomolecular condensates.

Membrane-dependent dynamics and dual translocation mechanisms of ABCB4: Insights from molecular dynamics simulations

ABCB4 is an ATP-binding cassette transporter expressed at the canalicular membrane of hepatocytes and responsible for translocating phosphatidylcholine into bile. Despite the recent cryo-EM structures of ABCB4, knowledge about the molecular mechanism of phosphatidylcholine transport remains fragmented. In this study, we used all-atom molecular dynamics simulations to investigate ABCB4 dynamics during its transport cycle, leveraging both symmetric and asymmetric membrane models. Our results demonstrate that membrane composition influences the local conformational dynamics of ABCB4, revealing distinct lipid-binding patterns across different conformers, particularly for cholesterol. We explored the two potential mechanisms for phosphatidylcholine translocation: the canonical ATP-driven alternating access model and the "credit-card swipe" model. Critical residues were identified for phosphatidylcholine binding and transport pathway modulation, supporting the canonical mechanism while also indicating a possible additional pathway. The conformer-specific roles of kinking in transmembrane helices (TMH4 and TMH10) were highlighted as key events in substrate translocation. Overall, ABCB4 may utilize a cooperative transport mechanism, integrating elements of both models to facilitate efficient phosphatidylcholine motion across the membrane. This study provides new insights into the relationship between membrane environment and ABCB4 function, contributing to our understanding of its role in bile physiology and susceptibility to genetic and xenobiotic influences.

Non-van-der-Waals Oriented Two-Dimensional UiO-66 Films by Rapid Aqueous Synthesis at Room Temperature

The synthesis of MOFs in a two-dimensional (2D) film morphology is attractive for several applications including molecular and ionic separation. However, 2D MOFs have only been reported from structures that crystallize in lamellar morphology, where layers are held together by van der Waals (vdW) interaction. By comparison, UiO-66, one of the most studied MOFs because of its exceptional chemical stability, has only been reported in three-dimensional (3D) morphology. 2D UiO-66 is challenging to obtain given the robust isotropic bonds in its cubic crystal structure. Herein, we report the first synthesis of non-vdW 2D UiO-66-NH2 by developing crystal growth conditions that promote in-plane growth over out-of-plane growth. Continuous, oriented UiO-66-NH2 film with thickness tunable in the range of 0.5 to 2 unit cells could be obtained by sustainable, scalable chemistry, which yielded attractive ion-ion selectivity. The preparation of non-vdW 2D MOF is highly attractive to advance the field of MOF films for diverse applications.

Nanomedicine's shining armor: understanding and leveraging the metal-phenolic networks

Metal-phenolic networks (MPNs), which comprise supramolecular amorphous networks formed by interlinking polyphenols with metal ions, garner escalating interest within the realm of nanomedicine. Presently, a comprehensive synthesis of the cumulative research advancements and utilizations of MPNs in nanomedicine remains absent. Thus, this review endeavors to firstly delineate the characteristic polyphenols, metal ions, and their intricate interaction modalities within MPNs. Subsequently, it elucidates the merits and demerits of diverse synthesis methodologies employed for MPNs, alongside exploring their potential functional attributes. Furthermore, it consolidates the diverse applications of MPNs across various nanomedical domains encompassing tumor therapy, antimicrobial interventions, medical imaging, among others. Moreover, a meticulous exposition of the journey of MPNs from their ingress into the human body to eventual excretion is provided. Lastly, the persistent challenges and promising avenues pertaining to MPNs are delineated. Hence, this review offering a comprehensive exposition on the current advancements of MPNs in nanomedicine, consequently offering indirect insights into their potential clinical implementation.

Optimizing cation-π force fields for molecular dynamics studies of competitive solvation in conjugated organosulfur polymers for lithium-sulfur batteries

Lithium-sulfur (Li/S) batteries are emerging as a next-generation energy storage technology due to their high theoretical energy density and cost-effectiveness. π-Conjugated organosulfur polymers, such as poly(4-(thiophene-3-yl)benzenethiol) (PTBT), have shown promise in overcoming challenges such as the polysulfide shuttle effect by providing a conductive framework and enabling sulfur copolymerization. In these cathodes, cation-π interactions significantly influence Li+ diffusion and storage properties in π-conjugated cathodes, but classical OPLS-AA force fields fail to capture these effects. This study employs a bottom-up approach based on density functional theory (DFT) to optimize the nonbonded interaction parameters (OPLS-AA/corr.), particularly for the Li+-π interactions with the PTBT polymer. Following prior work, we used an ion-induced dipole potential to model the cation-π interactions. The impact of the solvent on the PTBT monomers was examined by computing the potential of mean force (PMF) between PTBT monomers and Li+ ions in both explicit and implicit solvents using the Boltzmann inversion of probability distributions close to room temperature. In the implicit solvent case, the magnitude of the binding free energy decreased with increasing dielectric constant, as the dominant electrostatics scaled with the dielectric constant. In contrast, in the explicit solvent case, considering the mixtures of organic solvent DME and DOL, the binding free energy shows minimal dependence on solvent composition due to the competing interaction of TBT and Li+ with the solvent molecules. However, increasing salt concentration decreases the binding free energy due to Debye-Hückel screening effects. In general, this work suggests that the optimized parameters can be widely used in the simulation of polymers in electrolytes for the Li/S battery to enhance the representation of cation-π interactions for a fixed charge force field.

Boosting CO2 and benzene adsorption through π-hole substitution in β-diketonate Cu(ii) complex within non-porous adaptive crystals

The effect of quadrupole moments in non-porous adaptive crystals of fully, partially, and non-fluorinated β-diketonate Cu(ii) complexes on CO2 and hydrocarbon adsorption was systematically investigated using structurally similar models with distinct electronic properties. The fully fluorinated complex significantly enhanced CO2 adsorption, particularly at low pressures (<0.1 P/P 0), achieving a 1 : 1 stoichiometric ratio through quadrupole interactions, where the positively polarized regions of electrostatic potentials (ESPs) on the Cu(ii) center and pentafluorophenyl rings facilitated CO2 binding via its quadrupole nature. The perfluorinated complex also exhibited a stepwise vapor adsorption of benzene (C6H6), exhibiting distinct hysteresis and a 1 : 3 stoichiometric ratio, driven by M⋯π and π-hole⋯π interactions. In contrast, the partially fluorinated complex and non-fluorinated [Cu(dbm)2] (dbm = dibenzoylmethanido-) showed significantly reduced adsorption capabilities, reflecting the critical role of quadrupole moments and charge distribution in molecular recognition. The poor guest insertion of hexafluorobenzene (C6F6) into the perfluorinated complex highlighted the impact of electrostatic repulsion between similarly positive quadrupole moments. The gas adsorption studies further demonstrated differences in the kinetics and adsorption behavior of CO2, C2H n (n = 2, 4, 6), and aromatic vapors, underscoring the importance of quadrupole design. These findings provide a rational framework for the development of advanced host-guest materials tailored for selective adsorption and separation applications.

Cation-lone Pair Interaction in Alkali/Alkaline Earth Metal Ion-Heavier Borazine Analogue Complexes

The present study is the first report on the formation of alkali/alkaline earth metal ion-heavier borazine analogue complexes via cation-lone pair interaction. Density functional calculations are performed in scrutinizing the complex formation between alkali (Li+, Na+, K+)/alkaline earth (Be2+, Mg2+, Ca2+) metal ions and heavier borazine analogues (HBA) viz. B3P3H6, Al3N3H6, Al3P3H6, Al3As3H6, and Ga3P3H6. The complexes are found to be stable in gas phase with stabilization energies within the range 26.40-324.74 kcal mol-1. The stability can be attributed to the polarizing power of the involved metal ions. Presence of solvent phase exerted notable impact on the stability of the complexes; stability is reduced significantly with the increase in solvent polarity. The process of complexation is exothermic and spontaneous. QTAIM analysis indicated the presence of both ionic and covalent interaction between HBAs and metal ions. HOMO energy, Wiberg bond index, NCI-isosurface and RDG plot analysis revealed the major role of cation-lone pair interaction in the complexation process.

Cation-π Bonding in Actinides: UOx+(Benzene) (x = 0, 1, 2) Complexes Studied with Threshold Photodissociation Spectroscopy and Theory

Cation-π complexes of the form UOx+(benzene) (x = 0, 1, 2) are produced by laser vaporization and cooled in a supersonic molecular beam. These ions are mass selected and studied with UV-visible laser photodissociation spectroscopy. Each of these complexes photodissociates by elimination of the benzene ligand. Above an energetic threshold, the absorption and photodissociation are continuous, indicating a high density of strongly coupled electronic states. The thresholds for the dissociation of each of these three complexes are measured and assigned as their respective bond dissociation energies. The bond energies determined [U+-(benzene): 42.5 ± 0.3 kcal/mol; UO+-(benzene): 41.0 ± 0.3 kcal/mol; UO2+-(benzene): 39.7 ± 0.3 kcal/mol] are comparable to those of transition metal ion-benzene complexes. Computational studies at the DFT/B3LYP level complement the experiments, predicting dissociation energies in reasonably good agreement with the experiments. Experiments and theory agree that the U+(benzene) complex is more strongly bound than its corresponding oxide ions. This new thermochemistry on actinide cation-π bonding should stimulate higher-level computational studies on these systems.

Spectral fingerprints of DOM-tungsten interactions: Linking molecular binding to conformational changes

Tungsten (W), a widely used yet understudied emerging contaminant, forms oxyanions in aqueous environments, distinguishing it from conventional heavy metals. While dissolved organic matter (DOM) demonstrates considerable potential for W binding, DOM-W interactions remain largely unexplored. Of particular significance, yet frequently overlooked, are the conformational changes in DOM during W binding processes. This study proposes a novel theoretical framework integrating superposition and charge transfer models to elucidate the complexity of these interactions. By combining spectroscopic techniques and photophysical models, we revealed that aromatic compounds containing 1-3 rings, especially monocyclic aromatic protein-like components, exhibit high affinity for W (logK=3.74-4.00). Phenolic hydroxyls served as primary binding sites for W, with aromatic rings facilitating binding through π interactions. Importantly, W binding to aromatic compounds induced conformational changes in DOM, transitioning from a loosely aggregated state to a more compact configuration. These changes facilitated W encapsulation within DOM through the synergistic effects of hydrophobic interactions, hydrogen/π-hydrogen bonding and π-stacking, potentially leading to stable trapping of W. Two-dimensional correlation spectroscopy analysis elucidated the sequential encapsulation process, involving phenolic, aromatic carboxylic/aliphatic carboxylic, polysaccharides, and aliphatics. The intricate behavior of DOM-W binding profoundly reshapes DOM's conformation, subtly yet significantly orchestrating W's binding affinity, environmental transport, and bioavailability in aquatic ecosystems.

Graphene oxide and its derivatives films for sustained-release trace element zinc based on cation-π interaction

Preventing and controlling agricultural non-point-source pollution, advancing the agricultural industry, and facilitating cation-π interaction to address cation instability and fertilizer loss are crucial for advancing agricultural sustainability. Due to the unique π-bond characteristics of GO (graphene oxide), it was selected as a cation carrier to improve fertilizer anti-loss capabilities and facilitate the effective release of nutrient ions. By adjusting the interface properties of GO, RGO (rippled graphene oxide) and CGO (crumpled graphene oxide) were successfully prepared, and their interactions with cations and the impact on sustained-release performance were studied. The selected optimal kinetic model provides a theoretical basis for material design. The results indicate that RGO-Zn1 (Zn2+/RGO = 16.7%) can not only effectively control agricultural non-point source pollution but also promote the cultivation of high-zinc rice. This study not only proposes an innovative solution for soil improvement and agricultural transformation and upgrading but also offers fundamental scientific insights into the cation-π interaction mechanism during transmembrane permeation.

Heteroatomic molecules for coordination engineering towards advanced Pb-free Sn-based perovskite photovoltaics

As an ideal eco-friendly Pb-free optoelectronic material, Sn-based perovskites have made significant progress in the field of photovoltaics, and the highest power conversion efficiency (PCE) of Sn-based perovskite solar cells (PSCs) has been currently approaching 16%. In the course of development, various strategies have been proposed to improve the PCE and stability of Sn-based PSCs by solving the inherent problems of Sn2+, including high Lewis acidity and easy oxidation. Notably, the recent breakthrough comes from the development of heteroatomic coordination molecules to control the characteristics of Sn-based perovskites, which are considered to be vital for realizing efficient PSCs. In this review, the up-to-date advances in the design of heteroatomic molecules and their key functions in the fabrication of Sn-based perovskite films are comprehensively summarized. Firstly, the design principles of heteroatomic coordination molecules and their impact on the colloidal chemistry, crystallization dynamics, and defect properties of Sn-based perovskites are introduced. Then, state-of-the-art heteroatomic coordination molecules for efficient Sn-based PSCs are discussed in terms of their heteroatom types and functional groups. Lastly, we shed some light on the current challenges and future perspectives regarding the rational design of heteroatomic coordination molecules for further boosting the performance of Sn-based PSCs.

Phase separation and ageing of glycine-rich protein from tick adhesive

Hard ticks feed on their host for multiple days. To ensure firm attachment, they secrete a protein-rich saliva that eventually forms a solid cement cone. The underlying mechanism of this liquid-to-solid transition is currently not understood. This study focuses on the phase transitions of a disordered glycine-rich protein (GRP) found in tick saliva. We show that GRP undergoes liquid-liquid phase separation via simple coacervation to form biomolecular condensates in salty environments. Cation-π and π-π interactions mediated by periodically placed arginine and aromatic amino-acid residues are the primary driving forces that promote phase separation. Interestingly, GRP condensates exhibit ageing by undergoing liquid-to-gel transition over time and exhibit adhesive properties, similar to the naturally occurring cement cone. Finally, we provide evidence for protein-rich condensates in natural tick saliva. Our findings provide a starting point to gain further insights into the bioadhesion of ticks, to develop novel tick control strategies, and towards achieving biomedical applications such as tissue sealants.

Host-Guest Adduct as a Stimuli-Responsive Prodrug: Enzyme-Triggered Self-Assembly Process of a Short Peptide Within Mitochondria to Induce Cell Apoptosis

To address the issue of nonspecific biodistribution of a chemotherapeutic drug, stable [2]pseudorotaxane complexes (PK@CAOPP and PR@CAOPP) are used to demonstrate a proof of concept. Cationic -PPh3 + moiety in CAOPP allows specific localization of the PK@CAOPP/ PR@CAOPP in the mitochondrial membrane (MM). Electrostatic interaction between the cationic LysinePK or ArgininePR moiety and the negatively charged phosphoesterCAOPP functionality in CAOPP favours strong adduct formation. The ALP-induced hydrolytic cleavage of the phosphoester moiety in cancer cells triggers dephosphorylation and releases PK/ PR moiety from PK@CAOPP/PR@CAOPP. PK or PR, derived from the Phe-Phe dipeptide, formed fibril-like molecular aggregates in the MM to induce dysfunction, depolarization, ROS generation and apoptotic MCF7 cell death. Such phenomena were not observed in ALP-negative HEK293 normal cells. These propositions were confirmed through control studies using NBDK and PE, other guest molecules. Smaller size and inclusion of the short peptides (PK or PR) within the hydrophobic interior of CAOPP, were attributed to their stability in blood serum. Thus, we have demonstrated the use of supramolecular adducts as a potential therapeutic option for treating cancer cells without affecting healthy cells. The efficacy was also established with an in-vivo MCF7 tumour xenograft model using Balb/c nude mice.

Computationally Assisted Noncanonical Amino Acid Incorporation

Genetic encoding of noncanonical amino acids (ncAAs) with desired functionalities is an invaluable tool for the study of biological processes and the development of therapeutic drugs. However, existing ncAA incorporation strategies are rather time-consuming and have relatively low success rates. Here, we develop a virtual ncAA screener based on the analysis and modeling of the chemical properties of all reported ncAA substrates to virtually determine the recognition potential of candidate ncAAs. Using this virtual screener, we designed and incorporated several novel Lys and Phe derivatives into proteins for various downstream applications. Among them, the genetic encoding of an electron-rich Phe analog, 3-dimethylamino-phenylalanine, was successfully applied to enhance the cation-π interaction between histone methylation and its reader proteins. Thus, our virtual screener provides a fast and powerful strategy to efficiently incorporate ncAAs with diverse functionalities.

Computational insight into the formation of cation-π/cation-lone pair complexes between 3d-metal (II) ions and furan

CONTEXT

Cation-π and cation-lone pair interactions between 3d-metal (II) ions [Fe(II), Co(II), Ni(II) and Cu(II)] and furan are explored in the formation of 1:1 and 1:2 type complexes. Both cation-π (IEgas = -192.27 to -312.65 kcal mol-1) and cation-lone pair (IEgas = -163.13 to -271.76 kcal mol-1) interactions are reasonably strong and lead to the formation of stable 1:1 and 1:2 type complexes in gas phase. The complexes are also stable in solvent phase, but their stability is reduced significantly in presence of solvent dielectrics, especially in ethanol, DMSO and water. Formation of the complexes is thermodynamically favourable (exothermic and spontaneous). Charge transfer (Δq = 0.62 to 1.92 e-), Laplacian of electron density (∇2ρ = 0.1435 to 0.6628 au) and total electron energy density (H(r) = -0.0019 to -0.0436 au) analysis have argued in favour of partial ionic and partial covalent character of the interactions.

METHODS

Density functional theory (DFT) is exclusively used for the study. Polarizable continuum model (PCM) is used to perform solvent phase study. Natural bond orbital (NBO), quantum theory of atoms in molecules (QTAIM) and non-covalent interaction (NCI) analyses are performed for understanding other aspects of complex formation.

Soft nanoforest of metal single atoms for free diffusion catalysis

Metal single atoms are of increasing importance in catalytic reactions. However, the mass diffusion is yet substantially limited by the confined surface of the support in comparison to homogeneous catalysis. Here, we demonstrate that cylindrical micellar brushes with highly solvated poly(2-vinylpyridine) coronas can immobilize 33 types of metal single atoms with 8.3 to 40.9 weight % contents on conventional electrodes under ambient conditions. This is favored by the forest-like hierarchically open soft structure of the micellar brushes and the dynamic coordination between the metals and the pyridine groups. It was found that the nanoforests of individual noble metal single atoms can be well solvated in an aqueous electrolyte to comprehensively expose the atomic active sites and the nanoforest of Pt single atoms on nickel foam reveals high electrochemical performance for hydrogen evolution. The micellar brush support also enables the simultaneous anchoring of multiple single atoms on the cathode of an anion-exchange membrane electrolyzer for long-term stable water electrolysis.

Research on advanced photoresponsive azobenzene hydrogels with push-pull electronic effects: a breakthrough in photoswitchable adhesive technologies

Smart materials that adapt to various stimuli, such as light, hold immense potential across many fields. Photoresponsive molecules like azobenzenes, which undergo E-Z photoisomerization when exposed to light, are particularly valuable for applications in smart coatings, light-controlled adhesives, and photoresists in semiconductors and integrated circuits. Despite advances in using azobenzene moieties for stimuli-responsive adhesives, the role of push-pull electronic effects in regulating reversible adhesion remains largely unexplored. In this study, we investigate for the first time photo-controlled hydrogel adhesives of azobenzene with different push-pull electronic groups. We synthesized the monomers 4-methoxyazobenzene acrylate (ABOMe), azobenzene acrylate (ABH), and 4-nitroazobenzene acrylate (ABNO2), and examined their effects on reversible adhesion properties. By incorporating these azobenzene monomers into acrylamide, dialdehyde-functionalized poly(ethylene glycol), and [3-(methacryloylamino)propyl]-trimethylammonium chloride, we prepared ABOMe, ABH, and ABNO2 ionic hydrogels. Our research findings demonstrate that only the ABOMe ionic hydrogel exhibits reversible adhesion. This is due to its distinct transition state mechanism compared to ABH and ABNO2, which enables efficient E-Z photoisomerization and drives its reversible adhesion properties. Notably, the ABOMe ionic hydrogel reveals an outstanding skin adhesion strength of 360.7 ± 10.1 kPa, surpassing values reported in current literature. This exceptional adhesion is attributed to Schiff base reactions, monopole-quadrupole interactions, π-π interactions, and hydrogen bonding with skin amino acids. Additionally, the ABOMe hydrogel exhibits excellent reversible self-healing capabilities, significantly enhancing its potential for injectable medical applications. This research underscores the importance of integrating multifunctional properties into a single system, opening new possibilities for innovative and durable adhesive materials.

A Self-Healing Transparent Waterborne Polyurethane Film with High Strength and Toughness Based on Cation-π Interactions

Giving waterborne polyurethane (WPU) coatings self-healing properties not only maintains the coating's environmentally friendly characteristics but also extends the material's service life and enables sustainable development. Therefore, self-healing WPUs have received an increasing amount of attention from researchers. However, it is a serious challenge to overcome the original shortcomings of WPU coatings, such as poor strength, low hardness, and weak adhesion, as well as the introduction of self-healing properties resulting in further degradation of strength-mechanical properties and heat resistance. Here, we provide a design strategy to introduce a noncovalent physical cross-linking network based on cation-π interactions into the WPU molecular structure to prepare a series of self-healing transparent WPU coatings with high strength. The coating exhibited a very high tensile strength (66.11 ± 3.28 MPa) and excellent flexibility (0.5 mm), with a scratch repair efficiency of up to 98.2% for 12 h of repair at 60 °C. In addition, the coating also has good optical properties and has broad application prospects in the fields of transparent protective coatings and adhesives.

Characterization and structural analysis of a leucine aminopeptidase using site-directed mutagenesis

Amp0279 (EC 3.4.11.24, GenBank: CP000817.1) is a Co2+-dependent leucine aminopeptidase from the Lysinibacillus sphaericus C3-41 genome. After analyses using molecular docking and spatial structure analysis, site-directed mutagenesis mutants were performed as Amp0279-R131E, Amp0279-R131H, Amp0279-R131A and Amp0279-E349D. The optimum pH of Amp0279-R131E was shifted from the original 8.5 to 7.5, and the overall electrostatic potential was shifted towards acidic. Compared with the original enzyme, the mutant proteins all gained better structural stability, especially the apparent melting temperature (Tm) of Amp0279-R131H increased from 41.8 to 45.5 °C. Morever, when protein was bound to the substrate, the Tm of Amp0279-R131E was increased by 7.3 °C and Amp0279-R131H increased by 5.4 °C, compared to the original enzyme. This is consistent with the results that the mutants acquired higher binding energies to the substrates, and an increase the hydrogen bonding force. In addition, the molecular docking of mutant and substrate revealed that the truncation of R131 contributes to the increase in the binding capacity of the substrate molecules to the active centre. In contrast, the presence of π-Cation interactions generated by R131 with the substrate has an important effect on the ability of Amp0279 to hydrolyse the substrate. This study demostrated that R131 is a key site for activity and stability, which is important in the future exploration of the functional structure of Amp0279.

Intermolecular interaction potential maps from energy decomposition for interpreting reactivity and intermolecular interactions

The electrostatic potential (ESP) has been widely used to visualize electrostatic interactions about a molecule. However, electrostatic effects are often insufficient for capturing the entirety of an interaction or a reaction of interest. In this investigation, intermolecular interaction potential maps (IMIPs), constructed from the potentials derived from energy decomposition analysis (EDA) using density functional theory, were developed and applied to provide unique insight into molecular interactions and reactivity. To this end, rather than constructing a potential map from probe point charge interactions, IMIPs were constructed from probe interactions with small molecular fragments, including CH3+, CH3-, benzene, and atomic probes including alkali metals, transition metals, and halides. The interaction potentials are further decomposed producing IMIPs for each interaction component using EDA (electrostatic, orbital, steric, etc.). The IMIPs are applied to the study of various interactions including cation-π and anion-π interactions, electrophilic and nucleophilic aromatic substitution, Lewis acid activation, π-stacking, endohedral fullerenes, and select organometallics which reveal fundamental insight into the positional preferences and physical origins of the interactions that otherwise would be difficult to uncover through other surface analyses.

Photodissociation Spectroscopy and Photofragment Imaging of the Mg+(Benzene) Complex

Tunable laser photodissociation spectroscopy and photofragment imaging experiments are employed to investigate the spectroscopy and dissociation dynamics of the Mg+(benzene) ion-molecule complex. When excited with ultraviolet radiation, Mg+(benzene) photodissociates efficiently, producing both Mg+ and benzene+ fragments, with branching ratios depending on the wavelength. The wavelength dependence of these processes are similar, with intense resonances at 330 and 241 nm and weaker features at 290 and 258 nm. Comparisons of the experimental spectra to those predicted by computational chemistry at the TD-DFT level allow assignment of these to metal ion-based (330 and 241 nm), charge-transfer (290 nm), and benzene-based (258 nm) transitions. However, the observation of the benzene cation fragment at all wavelengths, which can only result from charge-transfer, indicates unanticipated excited state dynamics. Spectroscopy experiments are complemented by photofragment imaging to investigate these dynamics. The high kinetic energy release indicates that multiphoton absorption based on the intense atomic resonances is responsible at least in part for the dissociation processes.

Design, Synthesis, Evaluation of Antitubercular Activity and Insilco Studies of Novel 1,5-Naphthyridin-2(1H)-One Pendent 1,2,3-Triazoles

A library of 1,5-Naphthyridin-2(1H)-one based 1,2,3-triazole analogues (11a-q) were synthesized via series of reactions such as protection, oxidation, cyclization and click chemistry. The new molecules were tested for their antitubercular activity against M. tuberculosis mc26230 and determined the minimum inhibitory concentration (MIC) employing Rifampicin as reference. The 3-cyano and 4-cyano substituted analogues 11e and 11f displayed superior activity with an MIC value of 4.0 μg/ml. Additionally, these potent molecules were tested for determination of their MBC values and ATP depletion assay showed a hopeful relative luminescence. Additionally, determined the MIC of 11e and 11f against multi-drug resistant strains of M. tuberculosis viz. mc2 8243, mc2 8247 and mc2 8259. The cytotoxicity of these two molecules presented no effects on normal cell. The profound results of these two molecules proved them as potential antitubercular agent. Further, molecular docking studies were portrayed against crystal structure of M. tuberculosis dihydrofolate reductase which garnered promising docking scores and binding interactions such as H-bond and hydrophobic. ADME prediction revealed their favorable drug-likeness characteristics.

Molecular characteristics of dissolved organic matter regulate the binding and migration of tungsten in porous media

Tungsten (W) is an emerging contaminant that poses potential risks to both the environment and human health. While dissolved organic matter (DOM) can significantly influence the W's environmental behavior in natural aquifers, the mechanisms by which DOM's molecular structure and functional group diversity impact W binding and migration remain unclear. Using molecular weight-fractionated soil and sediment DOM (<1 kDa, 1-100 kDa, and 100 kDa-0.45 μm), this study systematically investigated the relationship between DOM molecular characteristics and tungstate (WO42-) binding properties using multiple spectroscopic methods, including FTIR, fluorescence spectroscopy and XPS. The migration behavior of WO42- in porous media was also investigated through quartz sand column experiments. Results revealed that approximately 75 % of W was controlled by DOM, with over 50 % binding to low molecular weight DOM (<1 kDa). Tungsten bound to medium-high molecular weight DOM (1-100 kDa, >100 kDa) showed a greater propensity for retention, with the >100 kDa fractions demonstrating stronger selective binding to W, exhibiting distribution coefficients (Kmd) of 6.11 L/g and 10.69 L/g, respectively. Further analysis indicated that W primarily binds with aromatic rings, phenolic hydroxyls, polysaccharides, and carboxyl groups in DOM, potentially affecting DOM structural stability and consequently influencing W migration characteristics. Free W migration in quartz sand was primarily controlled by Langmuir monolayer adsorption, leading to local enrichment (Da = 6.83, Rd = 86.98). When bound to DOM, W's migration ability significantly increased (Rd = 8-10), with adsorption shifting to a Freundlich multilayer model, primarily controlled by convective transport (Npe = 27-62> > 1.96), while adsorption effects weakened (Da ≈ 1). This study, for the first time, systematically reveals the regulatory mechanisms of DOM molecular characteristics on tungsten's environmental behavior. It offers crucial parameter support for constructing tungsten migration models and provides important guidance for tungsten pollution risk assessment and remediation strategies.

Integrated computational strategies for Polypharmacological profiling and identification of anti-inflammatory targets in Rungia pectinata L

Rungia pectinata L. is an ethnomedicinal herb belonging to the Acanthaceae family and it presents a promising avenue for medicinal exploration, deeply rooted in traditional practices. Earlier research has demonstrated that the herb can effectively relieve the classic symptoms of inflammation. Nevertheless, comprehensive studies into the mechanisms underlying R. pectinata's beneficial impact on inflammation pathways, remain scarce. Hence, we employed an integrated approach combining network pharmacology, molecular docking and molecular dynamics simulations to explore the mechanisms underlying R. pectinata's anti-inflammatory activity. For this study, seven inflammation-related active ingredients were identified among 38 candidates, revealing 22 intersecting genes associated with inflammation. Protein-protein interaction (PPI) networks revealed three therapeutic targets: IL1B, PTGS2 and SRC. GO and KEGG pathway enrichment analyses indicated that the effects of R. pectinata are mediated by genes related to inflammation and cancer. Molecular docking studies identified trans-nerolidyl formate and widdrol as lead compounds while molecular dynamics simulations indicated stable compound-target complexes, with MM-PBSA calculations showing superior free energy values for SRC, suggesting implications in cancer pathways. Overall, this study offers valuable insights into the anti-inflammatory effects of R. pectinata, which may be mediated through key pathways involved in inflammation and cancer. This highlights the potential of R. pectinata in both anti-inflammatory and anticancer therapies. However, further experimental validation is necessary to confirm these findings.

Bioinspired Ion Host with Buried and Consecutive Binding Sites for Controlled Ion Dislocation

This study presents a bioinspired ion host featuring continuous binding sites arranged in a tunnel-like structure, closely resembling the selectivity filter of natural ion channels. Our investigation reveals that ions traverse these sites in a controlled, sequential manner due to the structural constraints, effectively mimicking the ion translocation process observed in natural channels. Unlike systems with open binding sites, our model facilitates sequential ion recognition state transitions, enabled by the deliberate design of the tunnel. Notably, we observe dual ion release kinetics, highlighting the system's capacity to maintain ion balance in complex environments and adapt to changing conditions. Additionally, we demonstrate selective binding of two different ions-a challenging task for systems lacking structured tunnels.

Alkali cation-π interactions in aqueous systems, modulating supramolecular stereoisomerism of nanoscopic metal-organic capsules

Contrary to common chemical intuition, cation-π interactions can persist in polar, aqueous reaction solutions, rather than in dry non-coordinative solvent systems. This account highlights how alkali ion-π interactions impart distinctive structure-influencing supramolecular forces that can be exploited in the preparation of nanoscopic metal-organic capsules. The incorporation of alkali ions from polar solutions into molecular pockets promotes the assembly of otherwise inaccessible capsular entities whose structures are distinctive to those of common polyoxovanadate clusters in which {V=O} moieties usually point radially to the outside, shielding the molecular entities. The applied concept is exemplified by homologous {V20} and {V30} cages, composed of inverted, hemispherical {V5O9} units. The number and geometrical organization of these {V5O9} sub-units in these cages are associated with prevailing cation- π interactions and competing steric effects. The stereoisomers of these resulting nano-sized objects are comparable to Alfred Werner-type structural isomers of simple mononuclear complexes in-line with fundamental coordination chemistry principles.

Defense systems of soil microorganisms in response to compound contamination by arsenic and polycyclic aromatic hydrocarbons

Arsenic and PAHs impose environmental stress on soil microorganisms, yet their compound effects remain poorly understood. While soil microorganisms possess the ability to metabolize As and PAHs, the mechanisms of microbial response are not fully elucidated. In our study, we established two simulated soil systems using soil collected from Xixi Wetland Park grassland, Hangzhou, China. The As-600 Group was contaminated with 600 mg/kg sodium arsenite, while the As-600-PAHs-30 Group received both 600 mg/kg sodium arsenite and 30 mg/kg PAHs (phenanthrene:fluoranthene:benzo[a]pyrene = 1:1:1). These systems were operated continuously for 270 days, and microbial responses were assessed using high-throughput sequencing and metagenomic analysis. Our findings revealed that compound contamination significantly promoted the abundance of microbial defense-related genes, with general defense genes increasing by 11.07 % ∼ 74.23 % and specific defense genes increasing by 44.13 % ∼ 55.74 %. The dominate species Rhodococcus adopts these general and specific defense mechanisms to resist compound pollution stress and gain ecological niche advantages, making it a candidate strain for soil remediation. Our study contributes to the assessment of ecological damage caused by As and PAHs from a microbial perspective and provides valuable insights for soil remediation.

A DFT Study of Band-Gap Tuning in 2D Black Phosphorus via Li+, Na+, Mg2+, and Ca2+ Ions

Black phosphorus (BP) and its two-dimensional derivative (2D-BP) have garnered significant attention as promising anode materials for electrochemical energy storage devices, including next-generation fast-charging batteries. However, the interactions between BP and light metal ions, as well as how these interactions influence BP's electronic properties, remain poorly understood. Here, we employed density functional theory (DFT) to investigate the effects of monovalent (Li+ and Na+) and divalent (Mg2+ and Ca2+) ions on the valence electronic structure of 2D-BP. Molecular orbital analysis revealed that the adsorption of divalent cations can significantly reduce the band gap, suggesting an enhancement in charge transfer rates. In contrast, the adsorption of monovalent cations had minimal impact on the band gap, suggesting the preservation of 2D-BP's intrinsic electrical properties. Energetic and charge analyses indicated that the extent of charge transfer primarily governs the ability of ions to modulate 2D-BP's electronic structure, especially under high-pressure conditions where ions are in close proximity to the 2D-BP surface. Moreover, charge polarization calculations revealed that, compared with monovalent cations, divalent cations induced greater polarization, disrupting the symmetry of the pristine 2D-BP and further influencing its electronic characteristics. These findings provide a molecular-level understanding of how ion interactions influence 2D-BP's electronic properties during ion-intercalation processes, where ions are in close proximity to the 2D-BP surface. Moreover, the calculated diffusion barrier results revealed the potential of 2D-BP as an effective anode material for lithium-ion, sodium-ion, and magnesium-ion batteries, though its performance may be limited for calcium-ion batteries. By extending our understanding of interactions between ions and 2D-BP, this work contributes to the design of efficient and reliable energy storage technologies, particularly for the next-generation fast-charging batteries.

Insights into the adsorption of emerging organic contaminant by low-cost readily separable modified jute fiber

A high-efficiency biosorbent based on the low-priced jute fiber was developed, characterized, and applied to remove the emerging organic contaminant diclofenac from aqueous solutions. Jute fiber was treated by NaOH (named AJF) followed by grafting different amounts of trimethyl[3-(trimethoxysilyl) propyl] ammonium chloride (named AJF-TTSAC). The composition, morphology, porosity, and adsorption features of the neat and modified jute fiber were evaluated and compared. The surface of neat JF was smooth, nonporous, and free of cracks. NaOH treatment increased the fibrillation, created cracks and grooves, and increased the oxygen content, total pore volume, and surface area. In comparison to AJF, grafting TTSAC filled in the crevices, grooves, and spaces between fibrillates, and decreased the total pore volume and surface area. The adsorption of diclofenac by the neat and modified JF occurred at highly acidic pHo and peaked at pHo 3. Among the neat and modified JF, AJF-TTSAC5 was the most efficient followed by AJF. The efficiency of AJF and AJF-TTSAC5 was highest using 1.00 g/L, at 35 °C and was not affected by the presence of NaCl. The Elovich, pseudo-first-order, and pseudo-second-order models described the adsorption kinetic satisfactorily with the marginal advantage of Elovich for AJF and pseudo-second-order for AJF-TTSAC5. The isotherm study exposed the multilayer and physisorption nature of the adsorption of diclofenac onto AJF and AJF-TTSAC5. The Langmuir monolayer saturation capacity of AJF-TTSAC5 was 37.43 mg/g which revealed its great potential relative to other adsorbents in the literature. The AJF and AJF-TTSAC5 were easily regenerated using distilled water and kept good performance for 5 repetitive cycles.

Squid-Inspired Anti-Salt Skin-Like Elastomers With Superhigh Damage Resistance for Aquatic Soft Robots

Cephalopod skins evolve multiple functions in response to environmental adaptation, encompassing nonlinear mechanoreponse, damage tolerance property, and resistance to seawater. Despite tremendous progress in skin-mimicking materials, the integration of these desirable properties into a single material system remains an ongoing challenge. Here, drawing inspiration from the structure of reflectin proteins in cephalopod skins, a long-term anti-salt elastomer with skin-like nonlinear mechanical properties and extraordinary damage resistance properties is presented. Cation-π interaction is incorporated to induce the geometrically confined nanophases of hydrogen bond domains, resulting in elastomers with exceptional true tensile strength (456.5 ± 68.9 MPa) and unprecedently high fracture energy (103.7 ± 45.7 kJ m-2). Furthermore, the cation-π interaction effectively protects the hydrogen bond domains from corrosion by high-concentration saline solution. The utilization of the resultant skin-like elastomer has been demonstrated by aquatic soft robotics capable of grasping sharp objects. The combined advantages render the present elastomer highly promising for salt enviroment applications, particularly in addressing the challenges posed by sweat, in vivo, and harsh oceanic environments.

Rational design of diblock copolymer enables efficient cytosolic protein delivery

Polymer-mediated cytosolic protein delivery demonstrates a promising strategy for the development of protein therapeutics. Here, we propose a new designed diblock copolymer which realizes efficient cytosolic protein delivery both in vitro and in vivo. The polymer contains one protein-binding block composed of phenylboronic acid (PBA) and N-(3-dimethylaminopropyl) (DMAP) pendant units for protein binding and endosomal escape, respectively, followed by the response to ATP enriched in the cytosol which triggers the protein release. The other block is PEG designed to improve particle size control and circulation in vivo. By optimizing the block composition, sequence and length of the copolymer, the optimal one (BP20) was identified with the binding block containing 20 units of both PBA and DMAP, randomly distributed along the chain. When mixed with proteins, the BP20 forms stable nanoparticles and mediates efficient cytosolic delivery of a wide range of proteins including enzymes, toxic proteins and CRISPR/Cas9 ribonucleoproteins (RNP), to various cell lines. The PEG block, especially when further modified with folic acid (FA), enables tumor-targeted delivery of Saporin in vivo, which significantly suppresses the tumor growth. Our results shall inspire the design of novel polymeric vehicles with robust capability for cytosolic protein delivery, which holds great potential for both biological research and therapeutic applications.

Impact of arsenic and PAHs compound contamination on microorganisms in coking sites: From a community to individual perspective

Arsenic (As) and polycyclic aromatic hydrocarbons (PAHs) are highly toxic, carcinogenic and teratogenic, and are commonly found in soils of industrial sites such as coking plants. They exert environmental stresses on soil microorganisms, but their compounding effects have not been systematically studied. Exploring the effects of compound contamination on microbial communities, species and genes is important for revealing the ecological damage caused by compound contamination and offering scientific insights into soil remediation strategies. In this study, we selected soil samples from 0 to 100 cm depth of a coking site with As, PAHs and compound contamination. We investigated the compound effects of As and PAHs on microbial communities by combining high-throughput sequencing, metagenomic sequencing and genome assembly. Compared with single contamination, compound contamination reduced the microbial community diversity by 10.68%-12.07% and reduced the community richness by 8.39%-18.61%. The compound contamination decreased 32.41%-46.02% of microbial PAHs metabolic gene abundance, 11.36%-19.25% of cell membrane transport gene abundance and 12.62%-57.77% of cell motility gene abundance. Xanthobacteraceae, the biomarker for compound contaminated soils, harbors arsenic reduction genes and PAHs degradation pathways of naphthalene, benzo [a]pyrene, fluorene, anthracene, and phenanthrene. Its broad metabolic capabilities, encompassing sulfur metabolism and quorum sensing, facilitate the acquisition of energy and nutrients, thereby conferring ecological niche advantages in compound contaminated environments. This study underscores the significant impacts of As and PAHs on the composition and function of microbial communities, thereby enriching our understanding of their combined effects and providing insights for the remediation of compound contaminated sites.

Solvent Effect on Cation&otimes;3π Interactions: A First-Principles Study

Cation⊗3π interactions play a special role in the behaviors of biological molecules and carbon-based materials in aqueous solutions, yet the effects of solvation on these interactions remain poorly understood. This study examines the sequential attachment of water molecules to cation⊗3π systems (cation = Li⁺, Na⁺, K⁺), revealing that solvation influences interaction strengths in opposing ways: solvation of the metal cation decreases the strengths of cation⊗3π interactions, while the solvation of the benzene molecule increases the strengths of cation⊗3π interactions, compared with the strengths of cation⊗3π interactions in the gas phase. The mechanism analyses revealed that in the presence of surrounding water molecules, the stability of cation⊗3π systems is generally enhanced by cation-π, π-π, water-π, and water-ion interactions, while water-water interactions typically have a destabilizing effect. In addition, the primary effect of water molecules at different adsorption sites is to modulate the Coulombic multipole-multipole interactions and the overlap between monomeric charge distributions, thereby influencing the changes in strengths of cation⊗3π interactions. Moreover, AIMD simulations further underscore the practical significance of cation⊗3π interactions. These findings provide valuable insights into the structures and the strengths of cation⊗3π interactions with the effect of solvation.

Accurate protein-ligand binding free energy estimation using QM/MM on multi-conformers predicted from classical mining minima

Accurate prediction of binding free energy is crucial for the rational design of drug candidates and understanding protein-ligand interactions. To address this, we have developed four protocols that combine QM/MM calculations and the mining minima (M2) method, tested on 9 targets and 203 ligands. Our protocols carry out free energy processing with or without conformational search on the selected conformers obtained from M2 calculations, where their force field atomic charge parameters are substituted with those obtained from a QM/MM calculation. The method achieved a high Pearson's correlation coefficient (0.81) with experimental binding free energies across diverse targets, demonstrating its generality. Using a differential evolution algorithm with a universal scaling factor of 0.2, we achieved a low mean absolute error of 0.60 kcal mol-1. This performance surpasses many existing methods and is comparable to popular relative binding free energy techniques but at significantly lower computational cost.

Quinine-Based Polymers Are Versatile and Effective Vehicles for Intracellular pDNA, mRNA, and Cas9 Protein Delivery

Quinine-based polymers have previously demonstrated promising performance in delivering pDNA in cells owing to their electrostatic as well as the nonelectrostatic interactions with pDNA. Herein, we evaluate whether quinine-based polymers are versatile for delivery of mRNA and Cas9-sgRNA complexes, especially in a serum-rich environment. Both mRNA and the Cas9-sgRNA complex are potent therapeutics that are structurally, chemically, and functionally very different from pDNA. By exploring a family of 7 quinine-based polymers that vary in monomer structure and polymer composition, we tested numerous formulations (42 with pDNA, 96 with mRNA, and 48 with Cas9-sgRNA) for payload-polymer complexation and delivery to compare payload-dependent structure-activity relationships. Several formulations demonstrated performance comparable to or better than the commercially available transfection agent jetPEI. The results of this study demonstrate the potential of quinine-based as a versatile carrier platform for delivering a wide range of nucleic acid therapeutics and serving the drug delivery needs in the field genetic medicine.

A Microscopically Heterogeneous Colloid Electrolyte for Extremely Fast-Charging and Long-Calendar-Life Silicon-Based Lithium-Ion Batteries

Fast-charging capability and calendar life are critical metrics in rechargeable batteries, especially in silicon-based batteries that are susceptible to sluggish Li+ desolvation kinetics and HF-induced corrosion. No existing electrolyte simultaneously tackles both these pivotal challenges. Here we report a microscopically heterogeneous covalent organic nanosheet (CON) colloid electrolyte for extremely fast-charging and long-calendar-life Si-based lithium-ion batteries. Theoretical calculations and operando Raman spectroscopy reveal the fundamental mechanism of the multiscale noncovalent interaction, which involves the mesoscopic CON attenuating the microscopic Li+-solvent coordination, thereby expediting the Li+ desolvation kinetics. This electrolyte design enables extremely fast-charging capabilities of the full cell, both at 8 C (83.1 % state of charge) and 10 C (81.3 % state of charge). Remarkably, the colloid electrolyte demonstrates record-breaking cycling performance at 10 C (capacity retention of 92.39 % after 400 cycles). Moreover, benefiting from the robust adsorption capability of mesoporous CON towards HF and water, a notable improvement is observed in the calendar life of the full cell. This study highlights the role of microscopically heterogeneous colloid electrolytes in enhancing the fast-charging capability and calendar life of Si-based Li-ion batteries. Our work offers fresh perspectives on electrolyte design with multiscale interactions, providing insightful guidance for the development of alkali-ion/metal batteries operating under harsh environments.

Noncanonical Amino Acids: Bringing New-to-Nature Functionalities to Biocatalysis

Biocatalysis has become an important component of modern organic chemistry, presenting an efficient and environmentally friendly approach to synthetic transformations. Advances in molecular biology, computational modeling, and protein engineering have unlocked the full potential of enzymes in various industrial applications. However, the inherent limitations of the natural building blocks have sparked a revolutionary shift. In vivo genetic incorporation of noncanonical amino acids exceeds the conventional 20 amino acids, opening new avenues for innovation. This review provides a comprehensive overview of applications of noncanonical amino acids in biocatalysis. We aim to examine the field from multiple perspectives, ranging from their impact on enzymatic reactions to the creation of novel active sites, and subsequent catalysis of new-to-nature reactions. Finally, we discuss the challenges, limitations, and promising opportunities within this dynamic research domain.

Serine 85 functions as a catalytic acid in the reprotonation process during EvAS-catalyzed astellifadiene biosynthesis

The deprotonation-reprotonation sequence introduces additional cyclization branches in terpene biosynthesis. However, the underlying mechanism remains poorly understood. In this study, we employed a combined approach of molecular dynamics (MD) simulations and site-directed mutagenesis on astellifadiene synthase EvAS from Emericella variecolor to investigate the role of a protonated S85 residue. This residue acts as a catalytic acid, previously unreported, that facilitates the reprotonation step in astellifadiene biosynthesis. Mutating S85 led to the production of a new tricyclic sesterterpene.

Polystyrene Chain Geometry Probed by Ion Mobility Mass Spectrometry and Molecular Dynamics Simulations

Polystyrene (PS) is a thermoplastic polymer commonly used in various applications due to its bulk properties. Designing functional polystyrenes with well-defined structures for targeted applications is of significant interest due to the rigid and apolar nature of the polymer chain. Progress is hindered to date by the limitations of current analytical methods in defining the atomistic-level folding of the polymer chain. The integration of ion mobility spectrometry and molecular dynamics simulations is beneficial in addressing these challenges. However, data on gas-phase polystyrene ions are rarely reported in the literature. We herein investigate the gas phase structure of polystyrene ions with different end groups to establish how the nature and the rigidity of the monomer unit affect the charge stabilization. We find that, in contrast to polar polymers in which the charges are located deep in the ionic globules, the charges in the PS ions are rather located at the periphery of the polymer backbone, leading to singly and doubly charged PS ions adopting dense elliptic-shaped structures. Molecular dynamics (MD) simulations indicate that the folding of the PS rigid chain is controlled by phenyl ring interactions with the charge ultimately remaining excluded from the core of the globular ions, whereas the folding of polyether ions is initiated by the folding of the flexible polyether chain around the sodium ion that remains deeply enclosed in the core of the ions.

Synergistic Cation-π Interactions and PEDOT-Based Protective Double-Layer for High Performance Zinc Anode

Ensuring effective and controlled zinc ion transportation is crucial for functionality of the solid electrolyte interphase (SEI) and overall performance in zinc-based battery systems. Herein the first-ever demonstration of incorporate cation-π interactions are provided in the SEI to effectively facilitate uniform zinc ion flux. The artificial SEI design involves the immobilization of 4-amino-p-terphenyl (TPA), a strong amphiphilic cation-π interaction donor, as a monolayer onto a conductive poly(3,4-ethylenedioxythiophene) (PEDOT) matrix, which enable the establishment of a robust network of cation-π interactions. Through a carefully-designed interfacial polymerization process, a high-quality, large-area, robust is achieved, thin polymeric TPA/PEDOT (TP) film for the use of artificial SEI. Consequently, this interphase exhibits exceptional cycling stability with low overpotential and enables high reversibility of Zn plating/stripping. Symmetrical cells with TP/Zn electrodes can be cycled for more than 3200 hours at 1 mA cm-2 and 1 mAh cm-2. And the asymmetric cells can cycle 3000 cycles stably with a high Coulomb efficiency of 99.78%. Also, under the extreme conditions of lean electrolyte and low N/P ratio, the battery with TP protective layer can still achieve ultra-stable cycle.

Aromatic Residues in Proteins: Re-Evaluating the Geometry and Energetics of π-π, Cation-π, and CH-π Interactions

Aromatic residues can participate in various biomolecular interactions, such as π-π, cation-π, and CH-π interactions, which are essential for protein structure and function. Here, we re-evaluate the geometry and energetics of these interactions using quantum mechanical (QM) calculations, focusing on pairwise interactions involving the aromatic amino acids Phe, Tyr, and Trp and the cationic amino acids Arg and Lys. Our findings reveal that π-π interactions, while energetically favorable, are less abundant in structured proteins than commonly assumed and are often overshadowed by previously underappreciated, yet prevalent, CH-π interactions. Cation-π interactions, particularly those involving Arg, show strong binding energies and a specific geometric preference toward stacked conformations, despite the global QM minimum, suggesting that a rather perpendicular T-shape conformation should be more favorable. Our results support a more nuanced understanding of protein stabilization via interactions involving aromatic residues. On the one hand, our results challenge the traditional emphasis on π-π interactions in structured proteins by showing that CH-π and cation-π interactions contribute significantly to their structure. On the other hand, π-π interactions appear to be key stabilizers in solvated regions and thus may be particularly important to the stabilization of intrinsically disordered proteins.