Conversion of triphenylphosphine oxide to organophosphorus via selective cleavage of C-P, O-P, and C-H bonds with sodium

Databases of ligand-binding pockets and protein-ligand interactions

Many research groups and institutions have created a variety of databases curating experimental and predicted data related to protein-ligand binding. The landscape of available databases is dynamic, with new databases emerging and established databases becoming defunct. Here, we review the current state of databases that contain binding pockets and protein-ligand binding interactions. We have compiled a list of such databases, fifty-three of which are currently available for use. We discuss variation in how binding pockets are defined and summarize pocket-finding methods. We organize the fifty-three databases into subgroups based on goals and contents, and describe standard use cases. We also illustrate that pockets within the same protein are characterized differently across different databases. Finally, we assess critical issues of sustainability, accessibility and redundancy.

Phosphination of aryl/alkyl bromides via Mn-mediated reductive C-P coupling

Mn-mediated reductive cross-coupling of organic bromides with 2-bromo-1,3,2-diazaphospholene was developed for efficient construction of C-P bonds under mild conditions. Mechanistic studies suggested that bromides are activated by in situ formed bis-diazaphospholene via hybrid radical and polar mechanisms.

Auto-Optimized Electro-Flow Reactor Platform for the in-situ Reduction of P(V) Oxide to P(III) and Their Application

Trivalent phosphine catalysis is mostly utilized to activate the carbon-carbon multiple bonds to form carbanion intermediate species and is highly sensitive to certain variables. Random manual multi-variables are critical for understanding the batch disabled regeneration of trivalent phosphine chemistry. We need the artificial intelligence-based system which can change the variable based on previously conducted failed experiment. Herein, we report an auto-optimized electro-micro-flow reactor platform for the in-situ reduction of stable P(V) oxide to sensitive P(III) and further utilized the method for Corey-Fuchs reaction.

Transparent Recombination Layers Design and Rational Characterizations for Efficient Two-Terminal Perovskite-Based Tandem Solar Cells

Two-terminal (2T) perovskite-based tandem solar cells (TSCs) arouse burgeoning interest in breaking the Shockley-Queisser (S-Q) limit of single-junction solar cells by combining two subcells with different bandgaps. However, the highest certified efficiency of 2T perovskite-based TSCs (33.9%) lags behind the theoretical limit (42-43%). A vital challenge limiting the development of 2T perovskite-based TSCs is the transparent recombination layers/interconnecting layers (RLs) design between two subcells. To improve the performance of 2T perovskite-based TSCs, RLs simultaneously fulfill the optical loss, contact resistance, carrier mobility, stress management, and conformal coverage requirements. In this review, the definition, functions, and requirements of RLs in 2T perovskite-based TSCs are presented. The insightful characterization methods applicable to RLs, which are inspiring for further research on the RLs both in 2T perovskite-based two-junction and multi-junction TSCs, are also highlighted. Finally, the key factors that currently limit the performance enhancement of RLs and the future directions that should be continuously focused on are summarized.

A first-in-class dual-chelator theranostic agent designed for use with imaging-therapy radiometal pairs of different elements

A covalent adduct of DFOB and DOTA separated by a l-lysine residue (DFOB-l-Lys-N 6-DOTA) exhibited remarkable regioselective metal binding, with {1H}-13C NMR spectral shifts supporting Zr(iv) coordinating to the DFOB unit, and Lu(iii) coordinating to the DOTA unit. This first-in-class, dual-chelator theranostic design could enable the use of imaging-therapy radiometal pairs of different elements, such as 89Zr for positron emission tomography (PET) imaging and 177Lu for low-energy β--particle radiation therapy. DFOB-l-Lys-N 6-DOTA was elaborated with an amine-terminated polyethylene glycol extender unit (PEG4) to give DFOB-N 2-(PEG4)-l-Lys-N 6-DOTA (compound D2) to enable installation of a phenyl-isothiocyanate group (Ph-NCS) for subsequent monoclonal antibody (mAb) conjugation (mAb = HuJ591). D2-mAb was radiolabeled with 89Zr or 177Lu to produce [89Zr]Zr-D2-mAb or [177Lu]Lu-D2-mAb, respectively, and in vivo PET/CT imaging and in vivo/ex vivo biodistribution properties measured with the matched controls [89Zr]Zr-DFOB-mAb or [177Lu]Lu-DOTA-mAb in a murine LNCaP prostate tumour xenograft model. The 89Zr-immuno-PET imaging function of [89Zr]Zr-D2-mAb and [89Zr]Zr-DFOB-mAb showed no significant difference in tumour accumulation at 48 or 120 h post injection. [89Zr]Zr-D2-mAb and [177Lu]Lu-D2-mAb showed similar ex vivo biodistribution properties at 120 h post-injection. Tumour uptake of [177Lu]Lu-D2-mAb shown by SPECT/CT imaging at 48 h and 120 h post-injection supported the therapeutic function of D2, which was corroborated by similar therapeutic efficacy between [177Lu]Lu-D2-mAb and [177Lu]Lu-DOTA-mAb, both showing a sustained reduction in tumour volume (>80% over 65 d) compared to vehicle. The work identifies D2 as a trifunctional chelator that could expand capabilities in mixed-element radiometal theranostics to improve dosimetry and the clinical outcomes of molecularly targeted radiation.

Post-translational modification-centric base editor screens to assess phosphorylation site functionality in high throughput

Signaling pathways that drive gene expression are typically depicted as having a dozen or so landmark phosphorylation and transcriptional events. In reality, thousands of dynamic post-translational modifications (PTMs) orchestrate nearly every cellular function, and we lack technologies to find causal links between these vast biochemical pathways and genetic circuits at scale. Here we describe the high-throughput, functional assessment of phosphorylation sites through the development of PTM-centric base editing coupled to phenotypic screens, directed by temporally resolved phosphoproteomics. Using T cell activation as a model, we observe hundreds of unstudied phosphorylation sites that modulate NFAT transcriptional activity. We identify the phosphorylation-mediated nuclear localization of PHLPP1, which promotes NFAT but inhibits NFκB activity. We also find that specific phosphosite mutants can alter gene expression in subtle yet distinct patterns, demonstrating the potential for fine-tuning transcriptional responses. Overall, base editor screening of PTM sites provides a powerful platform to dissect PTM function within signaling pathways.

Solvent-free transformation of protic ionic liquids into zwitterions

We synthesized several protic ionic liquids (ILs) composed of onium cations and the (trifluoromethylsulfonyl)(vinylsulfonyl)amide anion. The addition of a base catalytically facilitated their transformation into zwitterions (ZIs) under solvent-free conditions, which is a convenient method for synthesizing ZIs from ILs.

Microrail-assisted liposome trapping and aligning in microfluidic channels

Liposome assemblies with a specific shape are potential cell tissue models for studying intercellular communication. Microfluidic channels that can trap liposomes have been constructed to achieve efficient and high-throughput manipulation and observation of liposomes. However, the trapping and alignment of multiple liposomes in a specific space are still challenging because the liposomes are soft and easily ruptured. In this study, we focused on a microrail-assisted technique for manipulating water-in-oil (w/o) emulsions. In this technique, w/o emulsions are trapped under the microrails through a surface energy gradient. First, we investigated whether the microrail channel can be applied for liposome trapping and alignment and found that the numerical simulations showed that drag forces in the direction of the microrail acted on the liposomes, thereby moving the liposomes from the main channel to the microrail. Next, we designed a microrail device based on the simulation results and trapped liposomes using the device. Resultantly, 24.7 ± 8.5 liposomes were aligned under the microrail within an hour, and the microrail was filled with liposomes for 3 hours. Finally, we prepared the microrail devices with y-shaped and ring-shaped microrails and demonstrated the construction of liposome assemblies with specific shapes, not only the straight shape. Our results indicate that the microrail-assisted technique is a valuable method for manipulating liposomes because it has the potential to provide various-shaped liposome assemblies. We believe the microrail channel will be a powerful tool for constructing liposome-based cell-cell interaction models.

Chemodivergent Synthesis of Polycyclic Aromatic Diarylamines and Carbazoles by Thermal/Photochemical Process-Controlled Dephosphinylative Functionalizations of Amino(phosphinyl)arenes

A chemodivergent synthesis of polycyclic aromatic diarylamines and carbazoles was established by employing thermally or photochemically controlled processes using KOtBu/1,10-phenanthroline. The synthetic processes involved the dephosphinylation of 9-amino-10-(phosphinyl)phenanthrenes, which were obtained through a regioselective palladium-catalyzed direct [4 + 2] benzannulation of phosphinyl ynamines with 2-iodobiphenyls. When the dephosphinylation was conducted under heating conditions (∼100 °C), it proceeded to yield 9-aminophenanthrene. However, when the reaction was performed under the illumination of purple light (LEDs, λmax = ca. 390 nm), KOtBu/1,10-phenanthroline promoted single-electron-transfer-triggered dephosphinylation followed by cyclization, producing the corresponding π-expanded carbazoles. We successfully synthesized a highly π-expanded dicarbazole through a dual dephosphinylative cyclization. Additionally, we present the optical properties of a series of amino compounds produced through the dephosphinylative processes.

CO2 capture using silica-immobilized dicationic ionic liquids with magnetic and non-magnetic properties

The need to find alternative materials to replace aqueous amine solutions for the capture of CO2 in post-combustion technologies is pressing. This study assesses the CO2 sorption capacity and CO2/N2 selectivity of three dicationic ionic liquids with distinct anions immobilized in commercial mesoporous silica support (SBA- 15). The samples were characterized by UART-FTIR, NMR, Raman, FESEM, TEM, TGA, Magnetometry (VSM), BET and BJH. The highest CO2 sorption capacity and CO2/N2 selectivity were obtained for sample SBA@DIL_2FeCl4 [at 1 bar and 25 °C; 57.31 (±0.02) mg CO2/g; 12.27 (±0.72) mg CO2/g]. The results were compared to pristine SBA-15 and revealed a similar sorption capacity, indicating that the IL has no impact on the CO2 sorption capacity of silica. On the other hand, selectivity was improved by approximately 3.8 times, demonstrating the affinity of the ionic liquid for the CO2 molecule. The material underwent multiple sorption/desorption cycles and proved to be stable and a promising option for use in industrial CO2 capture processes.

Sodium-Mediated Reductive C-C Bond Cleavage Assisted by Boryl Groups

In contrast to the well-established oxidative C=C double bond cleavage to give the corresponding carbonyl compounds, little is known about reductive C=C double bond cleavage. Here we report that C-C single bond cleavage in 1,2-diaryl-1,2-diborylethanes proceeds by reduction with sodium metal to yield α-boryl benzylsodium species. In combination with our previous reductive diboration of stilbenes, the overall transformation represents reductive cleavage of the C=C double bonds of stilbene to yield α-boryl-α-sodiated toluenes. This reductive two-step C=C double bond cleavage is applicable to ring-opening or ring-expansion reactions of polycyclic aromatic hydrocarbons.

Different anion (NO3- and OAc-)-controlled construction of dysprosium clusters with different shapes

The complex hydrolysis process and strong uncertainty of self-assembly rules have led to the precise synthesis of lanthanide clusters still being in the "blind-box" stage and simplifying the self-assembly process and developing reliable regulation strategies have attracted widespread attention. Herein, different anions are used to induce the construction of a series of dysprosium clusters with different shapes and connections. When the selected anion is NO3-, it blocks the coordination of metal sites around the cluster through the terminal group coordination mode, thereby controlling the growth of the cluster. When NO3- was changed to OAc-, OAc- adopted a bridging mode to induce modular units to build dysprosium clusters through an annular growth mechanism. Specifically, we selected 2-amino-6-methoxybenzoic acid, 2-hydroxybenzaldehyde, and Dy(NO3)3·6H2O to react under solvothermal conditions to obtain a pentanuclear dysprosium cluster (1). The five Dy(III) ions in 1 are distributed in upper and lower planes and are formed by the tight connection of nitrogen and oxygen atoms, and μ3-OH- bridges on the ligand. Next, octa-nuclear dysprosium cluster (2) were obtained by only regulating ligand substituents. The eight Dy(III) ions in 2 are tightly connected through ligand oxygen atoms, μ2-OH-, and μ3-OH- bridges, forming an elliptical {Dy/O} cluster core. Furthermore, only by changing NO3- to OAc-, a wheel-shaped tetradeca-nuclear dysprosium cluster (3) was obtained. Cluster 3 is composed of OAc- bridged multiple template Dy3L3 units and pulling of these template units connected by an annular growth mechanism forms a wheel-shaped cluster. The angle of the coordination site on NO3- is ∠ONO = 115°, which leads to the further extension of the metal sites on the periphery of clusters 1 and 2 through the terminal group coordination mode, thereby regulating the structural connection of the clusters. However, the angle of the coordination site on OAc- is ∠OCO = 128°, and a slightly increased angle leads to the formation of a ring-shaped cluster 3 by connecting the template units through bridging. This is a rare example of the controllable construction of lanthanide clusters with different shapes induced by the regulation of different anions, which provides a new method for the precise construction of lanthanide clusters with special shapes.

Sialic acids in infection and their potential use in detection and protection against pathogens

In structural terms, the sialic acids are a large family of nine carbon sugars based around an alpha-keto acid core. They are widely spread in nature, where they are often found to be involved in molecular recognition processes, including in development, immunology, health and disease. The prominence of sialic acids in infection is a result of their exposure at the non-reducing terminus of glycans in diverse glycolipids and glycoproteins. Herein, we survey representative aspects of sialic acid structure, recognition and exploitation in relation to infectious diseases, their diagnosis and prevention or treatment. Examples covered span influenza virus and Covid-19, Leishmania and Trypanosoma, algal viruses, Campylobacter, Streptococci and Helicobacter, and commensal Ruminococci.

Tandem templating strategies facilitate the assembly of calix[8]arene-supported Ln18 clusters

Calix[n]arenes offer ideal chemical functionality through the polyphenolic lower rim to construct nano-sized coordination clusters with lanthanide (Ln) metal ions (e.g., NdIII10, GdIII8). However, the number of metal centers they can accommodate is still limited compared to that achievable with smaller ligands (e.g., GdIII140, GdIII104). Here, we exploit a combination of the "anion template strategy" and "templating ligands" to synthesise three highly symmetric (D3h, trigonal planar) LnIII18 (Ln = La, Nd, and Gd) systems, representing the largest calix[n]arene-based coordination clusters yet. The LnIII18 fragment is templated by a chloride anion located at the center of the cluster, wherefrom twelve μ3-OH- ligands bind 'internally' to the eighteen LnIII ions. 'Externally' the metallic skeleton is connected by p-tert-butylcalix[8]arene, oxo, chloro and carbonate ligands. The crystal packing in the lattice reveals large cylindrical channels of ∼26 Å in diameter, whose pore volume corresponds to ∼50% of the unit cell volume (using a 1.2 Å spherical probe radius). Magnetic measurements reveal the predominance of weak antiferromagnetic exchange in the Gd analog. Heat capacity data of GdIII18 reveal a high magnetic entropy with -ΔSm = 23.7 J K-1 kg-1, indicating potential for engineering magnetic refrigerant materials with calix[8]arenes.

Coordination recognition of differential template units of lanthanide chiral chain

Coordination-driven self-assembly processes often produce remarkable structures. In particular, self-assembly processes mediated by chiral template units have provided research ideas for analyzing the formation of chiral macromolecules in living organisms. In this study, by regulating the proportion of reaction raw materials in the "one-pot" synthesis of lanthanide complexes, we constructed chiral template units with different coordination orientations. As a result, lanthanide chiral chains connected to different structures were obtained through the self-assembly process of coordination recognition. In particular, driven by coordination, chiral template units with codirectional coordination points (called cis configuration) coordinate solely with cis template units during the self-assembly process to obtain a one-dimensional (1D) chain R-1/S-1 with an "S"-shaped distribution. Moreover, chiral template units with reversed coordination sites (called trans configuration) and twisted chiral template units are connected solely to templates with the same configuration to form a 1D chain R-2/S-2 with an axial helix. A circular dichroism spectrum shows that R-1/S-1 and R-2/S-2 are two pairs of enantiomers. The controllable construction of these two differential 1D chains is of great significance for studying coordination recognition at the molecular level. To the best of our knowledge, this is the first study to construct a 1D lanthanide chain through the self-assembly process of coordination recognition. The assembly process of nucleotides to form a hierarchical structure is simulated. This work provides a vivid example of the controllable synthesis of lanthanide complexes with precise structures and offers a new perspective on the formation process of chiral macromolecules that simulates natural processes.

Beyond Triphenylphosphine: Advances on the Utilization of Triphenylphosphine Oxide

Triphenylphosphine oxide is a well-known industrial waste byproduct, and thousands of tons of it are generated every year. Due to its chemical stability and limited applications, settlement of this waste issue has drawn extensive attention from chemists. The reduction of triphenylphosphine oxide to triphenylphosphine is heretofore the most employed solution, and is well reviewed. In view of our recent studies on the selective and efficient conversion of Ph3P(O) to other valuable organophosphorus chemicals by using sodium, the present perspective mainly highlights the advances on the utilization of Ph3P(O) to prepare a diverse range of functional organophosphorus compounds, except Ph3P, via selective P-C, C-H, and P-O bond cleavages.

Aldehyde-mediated inhibition of asparagine biosynthesis has implications for diabetes and alcoholism

Patients with alcoholism and type 2 diabetes manifest altered metabolism, including elevated aldehyde levels and unusually low asparagine levels. We show that asparagine synthetase B (ASNS), the only human asparagine-forming enzyme, is inhibited by disease-relevant reactive aldehydes, including formaldehyde and acetaldehyde. Cellular studies show non-cytotoxic amounts of reactive aldehydes induce a decrease in asparagine levels. Biochemical analyses reveal inhibition results from reaction of the aldehydes with the catalytically important N-terminal cysteine of ASNS. The combined cellular and biochemical results suggest a possible mechanism underlying the low asparagine levels in alcoholism and diabetes. The results will stimulate research on the biological consequences of the reactions of aldehydes with nucleophilic residues.

Fabrication of Oriented Polycrystalline MOF Superstructures

The field of metal-organic frameworks (MOFs) has progressed beyond the design and exploration of powdery and single-crystalline materials. A current challenge is the fabrication of organized superstructures that can harness the directional properties of the individual constituent MOF crystals. To date, the progress in the fabrication methods of polycrystalline MOF superstructures has led to close-packed structures with defined crystalline orientation. By controlling the crystalline orientation, the MOF pore channels of the constituent crystals can be aligned along specific directions: these systems possess anisotropic properties including enhanced diffusion along specific directions, preferential orientation of guest species, and protection of functional guests. In this perspective, we discuss the current status of MOF research in the fabrication of oriented polycrystalline superstructures focusing on the specific crystalline directions of orientation. Three methods are examined in detail: the assembly from colloidal MOF solutions, the use of external fields for the alignment of MOF particles, and the heteroepitaxial ceramic-to-MOF growth. This perspective aims at promoting the progress of this field of research and inspiring the development of new protocols for the preparation of MOF systems with oriented pore channels, to enable advanced MOF-based devices with anisotropic properties.

Analytical probing of membranotropic effects of antimicrobial copper nanoparticles on lipid vesicles as membrane models

Copper nanoparticles (CuNPs) are antimicrobial agents that are increasingly being used in several real-life goods. However, concerns are arising about their potential toxicity and thus, appropriate legislation is being issued in various countries. In vitro exploration of the permeability and the distribution of nanoparticles in cell membranes should be explored as the first step towards the investigation of the toxicity mechanisms of metal nanoantimicrobials. In this work, phosphatidylcholine-based large unilamellar vesicles have been explored as mimics of cellular membranes to investigate the effect of ultra-small CuNPs on the physicochemical features of phospholipid membranes. 4 nm-sized CuNPs were synthesized by a wet-chemical route that involves glutathione as a stabilizer, with further characterization by UV-vis absorption spectroscopy, fluorescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) spectroscopy. Two fluorescent membrane probes bearing naphthalene moieties (laurdan and prodan) were used to monitor the bilayer structure and dynamics, as well as to demonstrate the strong membranotropic effects of CuNPs. The fluorescence spectroscopic studies were supported by dynamic light scattering (DLS) measurements and the calcein leakage assay. Additionally, the degree of perturbation of the phospholipid bilayer by CuNPs was compared against that of Cu2+ ions, the latter resulting in negligible effects. The findings suggested that CuNPs are able to damage the phospholipid membranes, leading to their agglomeration or disruption.

Understanding and controlling the nucleation and growth of metal-organic frameworks

Metal-organic frameworks offer a diverse landscape of building blocks to design high performance materials for implications in almost every major industry. With this diversity stems complex crystallization mechanisms with various pathways and intermediates. Crystallization studies have been key to the advancement of countless biological and synthetic systems, with MOFs being no exception. This review provides an overview of the current theories and fundamental chemistry used to decipher MOF crystallization. We then discuss how intrinsic and extrinsic synthetic parameters can be used as tools to modulate the crystallization pathway to produce MOF crystals with finely tuned physical and chemical properties. Experimental and computational methods are provided to guide the probing of MOF crystal formation on the molecular and bulk scale. Lastly, we summarize the recent major advances in the field and our outlook on the exciting future of MOF crystallization.

Low-Coordinate Magnesium Sulfide and Selenide Complexes

The reactions of [{(iPrDipNacNac)Mg}2] 1 (iPrDipnacnac = HC(iPrCNDip)2) with Ph3P═O at 100 °C afforded the phosphinate complex [(iPrDipNacNac)Mg(OPPh3)(OPPh2)] 3. Reactions of 1 with Ph3P═E (E = S, Se) proceeded rapidly at room temperature to low-coordinate chalcogenide complexes [{(iPrDipNacNac)Mg}2(μ-S)] 4 and [{(iPrDipNacNac)Mg}2(μ-Se)] 5, respectively. Similarly, reactions of RNHC═S ((MeCNR)2C═S with R = Me, Et, or iPr) with 1 afforded NHC adducts of magnesium sulfide complexes, [{(iPrDipNacNac)Mg(RNHC)}(μ-S){Mg(iPrDipNacNac)}] 6, that could alternatively be obtained by adding the appropriate RNHC to sulfide complex 4. Complex 4 reacted with 1-adamantylazide (AdN3) to give [{(iPrDipNacNac)Mg}2(μ-SN3Ad)] 7 and can form various simple donor adducts in solution, of which [(iPrDipNacNac)Mg(OAd)}2(μ-S)] 8a (OAd = 2-adamantanone) was structurally characterized. The nature of the ionic Mg-E-Mg unit is described by solution and solid-state studies of the complexes and by DFT computational investigations.

Real-time tilt undersampling optimization during electron tomography of beam sensitive samples using golden ratio scanning and RECAST3D

Electron tomography is a widely used technique for 3D structural analysis of nanomaterials, but it can cause damage to samples due to high electron doses and long exposure times. To minimize such damage, researchers often reduce beam exposure by acquiring fewer projections through tilt undersampling. However, this approach can also introduce reconstruction artifacts due to insufficient sampling. Therefore, it is important to determine the optimal number of projections that minimizes both beam exposure and undersampling artifacts for accurate reconstructions of beam-sensitive samples. Current methods for determining this optimal number of projections involve acquiring and post-processing multiple reconstructions with different numbers of projections, which can be time-consuming and requires multiple samples due to sample damage. To improve this process, we propose a protocol that combines golden ratio scanning and quasi-3D reconstruction to estimate the optimal number of projections in real-time during a single acquisition. This protocol was validated using simulated and realistic nanoparticles, and was successfully applied to reconstruct two beam-sensitive metal-organic framework complexes.

Chemical modification of proteins - challenges and trends at the start of the 2020s

Ribosomally expressed proteins perform multiple, versatile, and specialized tasks throughout Nature. In modern times, chemically modified proteins, including improved hormones, enzymes, and antibody-drug-conjugates have become available and have found advanced industrial and pharmaceutical applications. Chemical modification of proteins is used to introduce new functionalities, improve stability or drugability. Undertaking chemical reactions with proteins without compromising their native function is still a core challenge as proteins are large conformation dependent multifunctional molecules. Methods for functionalization ideally should be chemo-selective, site-selective, and undertaken under biocompatible conditions in aqueous buffer to prevent denaturation of the protein. Here the present challenges in the field are discussed and methods for modification of the 20 encoded amino acids as well as the N-/C-termini and protein backbone are presented. For each amino acid, common and traditional modification methods are presented first, followed by more recent ones.

Metal-free FRET macrocycles of perylenediimide and aza-BODIPY for multifunctional sensing

Two multichromophoric FRET macrocycles M1 [1+1] and M2 [2+2] with red emission (λ_em ∼ 721 nm) composed of perylenediimide (PDI) as the energy donor and aza-BODIPY (ABDP) as the energy acceptor were synthesized by click reaction in a metal-free fashion. M1 and M2 exhibited distinct reversible ratiometric temperature responsive emission with temperature sensitivities of 0.09-0.14% °C^-1 and owing to the redox active chromophores, they showed solution phase redox responsive reversible colour changes.

Estimating the Gibbs Hydration Energies of Actinium and Trans-Plutonium Actinides

The use of actinides for medical, scientific and technological purposes has gained momentum in the recent years. This creates a need to understand their interactions with biomolecules, both at the interface and as they become complexed. Calculation of the Gibbs binding energies of the ions to biomolecules, i. e., the Gibbs energy change associated with a transfer of an ion from the water phase to its binding site, could help to understand the actinides' toxicities and to design agents that bind them with high affinities. To this end, there is a need to obtain accurate reference values for actinide hydration, that for most actinides are not available from experiment. In this study, a set of ionic radii is developed that enables future calculations of binding energies for Pu³⁺ and five actinides with renewed scientific and technological interest: Ac³⁺ , Am³⁺ , Cm³⁺ , Bk³⁺ and Cf³⁺ . Reference hydration energies were calculated using quantum chemistry and ion solvation theory and agree well for all ions except Ac³⁺ , where ion solvation theory seems to underestimate the magnitude of the Gibbs hydration energy. The set of radii and reference energies that are presented here provide means to calculate binding energies for actinides and biomolecules.

Selectivity and stability of N-terminal targeting protein modification chemistries

Protein N-termini provide uniquely reactive motifs for single site protein modification. Though a number of reactions have been developed to target this site, the selectivity, generality, and stability of the conjugates formed has not been studied. We have therefore undertaken a comprehensive comparative study of the most promising methods for N-terminal protein modification, and find that there is no 'one size fits all' approach, necessitating reagent screening for a particular protein or application. Moreover, we observed limited stability in all cases, leading to a need for continued innovation and development in the bioconjugation field.

Polymorphs with Remarkably Distinct Physical and/or Chemical Properties

Polymorphism in crystals is known since 1822 and the credit goes to Mitscherlich who realized the existence of different crystal structures of the same compound while working with some arsenate and phosphate salts. Later on, this phenomenon was observed also in organic crystals. With the advent of different technologies, especially the easy availability of single crystal XRD instruments, polymorphism in crystals has become a common phenomenon. Almost 37 % of compounds (single component) are polymorphic to date. As the energies of the different polymorphic forms are very close to each other, small changes in crystallization conditions might lead to different polymorphic structures. As a result, sometimes it is difficult to control polymorphism. For this reason, it is considered to be a nuisance to crystal engineering. It has been realized that the property of a material depends not only on the molecular structure but also on its crystal structure. Therefore, it is not only of interest to academia but also has widespread applications in the materials science as well as pharmaceutical industries. In this review, we have discussed polymorphism which causes significant changes in materials properties in different fields of solid-state science, such as electrical, magnetic, SHG, thermal expansion, mechanical, luminescence, color, and pharmaceutical. Therefore, this review will interest researchers from supramolecular chemistry, materials science as well as medicinal chemistry.

Catalysis enabled synthesis, structures, and reactivities of fluorinated S8-corona[n]arenes (n = 8-12)

Previously inaccessible large S8-corona[n]arene macrocycles (n = 8-12) with alternating aryl and 1,4-C6F4 subunits are easily prepared on up to gram scales, without the need for chromatography (up to 45% yield, 10 different examples) through new high acceleration SNAr substitution protocols (catalytic NR4F in pyridine, R = H, Me, Bu). Macrocycle size and functionality are tunable by precursor and catalyst selection. Equivalent simple NR4F catalysis allows facile late-stage SNAr difunctionalisation of the ring C6F4 units with thiols (8 derivatives, typically 95+% yields) providing two-step access to highly functionalised fluoromacrocycle libraries. Macrocycle host binding supports fluoroaryl catalytic activation through contact ion pair binding of NR4F and solvent inclusion. In the solid-state, solvent inclusion also intimately controls macrocycle conformation and fluorine-fluorine interactions leading to spontaneous self-assembly into infinite columns with honeycomb-like lattices.

Evidence for long-term potentiation in phospholipid membranes

Biological supramolecular assemblies, such as phospholipid bilayer membranes, have been used to demonstrate signal processing via short-term synaptic plasticity (STP) in the form of paired pulse facilitation and depression, emulating the brain's efficiency and flexible cognitive capabilities. However, STP memory in lipid bilayers is volatile and cannot be stored or accessed over relevant periods of time, a key requirement for learning. Using droplet interface bilayers (DIBs) composed of lipids, water and hexadecane, and an electrical stimulation training protocol featuring repetitive sinusoidal voltage cycling, we show that DIBs displaying memcapacitive properties can also exhibit persistent synaptic plasticity in the form of long-term potentiation (LTP) associated with capacitive energy storage in the phospholipid bilayer. The time scales for the physical changes associated with the LTP range between minutes and hours, and are substantially longer than previous STP studies, where stored energy dissipated after only a few seconds. STP behavior is the result of reversible changes in bilayer area and thickness. On the other hand, LTP is the result of additional molecular and structural changes to the zwitterionic lipid headgroups and the dielectric properties of the lipid bilayer that result from the buildup of an increasingly asymmetric charge distribution at the bilayer interfaces.

Defined metal atom aggregates precisely incorporated into metal-organic frameworks

Nanosized metal aggregates (MAs), including metal nanoparticles (NPs) and nanoclusters (NCs), are often the active species in numerous applications. In order to maintain the active form of MAs in "use", they need to be anchored and stabilised, preventing agglomeration. In this context, metal-organic frameworks (MOFs), which exhibit a unique combination of properties, are of particular interest as a tunable and porous matrix to host MAs. A high degree of control in the synthesis towards atom-efficient and application-oriented MA@MOF composites is required to derive specific structure-property relationships and in turn to enable design of functions on the molecular level. Due to the versatility of MA@MOF (derived) materials, their applications are not limited to the obvious field of catalysis, but increasingly include 'out of the box' applications, for example medical diagnostics and theranostics, as well as specialised (bio-)sensoring techniques. This review focuses on recent advances in the controlled synthesis of MA@MOF materials en route to atom-precise MAs. The main synthetic strategies, namely 'ship-in-bottle', 'bottle-around-ship', and approaches to achieve novel hierarchical MA@MOF structures are highlighted and discussed while identifying their potential as well as their limitations. Hereby, an overview of standard characterisation methods that enable a systematic analysis procedure and state-of-art techniques that localise MA within MOF cavities are provided. While the perspectives of MA@MOF materials in general have been reviewed various times in the recent past, few atom-precise MAs inside MOFs have been reported so far, opening opportunities for future investigation.

An antibody scanning method for the detection of α-synuclein oligomers in the serum of Parkinson's disease patients

Misfolded α-synuclein oligomers are closely implicated in the pathology of Parkinson's disease and related synucleinopathies. The elusive nature of these aberrant assemblies makes it challenging to develop quantitative methods to detect them and modify their behavior. Existing detection methods use antibodies to bind α-synuclein aggregates in biofluids, although it remains challenging to raise antibodies against α-synuclein oligomers. To address this problem, we used an antibody scanning approach in which we designed a panel of 9 single-domain epitope-specific antibodies against α-synuclein. We screened these antibodies for their ability to inhibit the aggregation process of α-synuclein, finding that they affected the generation of α-synuclein oligomers to different extents. We then used these antibodies to investigate the size distribution and morphology of soluble α-synuclein aggregates in serum and cerebrospinal fluid samples from Parkinson's disease patients. Our results indicate that the approach that we present offers a promising route for the development of antibodies to characterize soluble α-synuclein aggregates in biofluids.

End-to-end differentiable construction of molecular mechanics force fields

Molecular mechanics (MM) potentials have long been a workhorse of computational chemistry. Leveraging accuracy and speed, these functional forms find use in a wide variety of applications in biomolecular modeling and drug discovery, from rapid virtual screening to detailed free energy calculations. Traditionally, MM potentials have relied on human-curated, inflexible, and poorly extensible discrete chemical perception rules (atom types) for applying parameters to small molecules or biopolymers, making it difficult to optimize both types and parameters to fit quantum chemical or physical property data. Here, we propose an alternative approach that uses graph neural networks to perceive chemical environments, producing continuous atom embeddings from which valence and nonbonded parameters can be predicted using invariance-preserving layers. Since all stages are built from smooth neural functions, the entire process-spanning chemical perception to parameter assignment-is modular and end-to-end differentiable with respect to model parameters, allowing new force fields to be easily constructed, extended, and applied to arbitrary molecules. We show that this approach is not only sufficiently expressive to reproduce legacy atom types, but that it can learn to accurately reproduce and extend existing molecular mechanics force fields. Trained with arbitrary loss functions, it can construct entirely new force fields self-consistently applicable to both biopolymers and small molecules directly from quantum chemical calculations, with superior fidelity than traditional atom or parameter typing schemes. When adapted to simultaneously fit partial charge models, espaloma delivers high-quality partial atomic charges orders of magnitude faster than current best-practices with low inaccuracy. When trained on the same quantum chemical small molecule dataset used to parameterize the Open Force Field ("Parsley") openff-1.2.0 small molecule force field augmented with a peptide dataset, the resulting espaloma model shows superior accuracy vis-á-vis experiments in computing relative alchemical free energy calculations for a popular benchmark. This approach is implemented in the free and open source package espaloma, available at https://github.com/choderalab/espaloma.

Precise size-control and functionalization of gold nanoparticles synthesized by plasma-liquid interactions: using carboxylic, amino, and thiol ligands

Using gold nanoparticles (GNPs) in high-standard applications requires GNPs to be fabricated with high-quality size and surface properties. Plasma-liquid interactions (PLIs) have the unique ability to synthesize GNPs without using any reducing agents, and the GNP surface is free of stabilizing agents. It is an extreme advantage that ensures success for the subsequent functionalization processes for GNPs. However, fabricating GNPs via PLIs at the desired size has still been a challenge. Here, we present a simple approach to achieving the precise size-control of GNPs synthesized by PLIs. By adding suitable ligands to the precursor solution, the ligands wrap GNPs which interrupts and slows down the rapid growth of GNPs under PLIs. This way, the size of the GNPs can be precisely controlled by adjusting the ligand concentration. Our results showed that the size of the GNPs in the range of 10-60 nm can be fitted to reciprocal functions of the ligand concentration. The potency of the size-control depends on the type of ligands in the order of thiol > amine > carboxylate. The size-control has been well investigated with four common ligands: l-cysteine, glucosamine, salicylic acid, and terephthalic acid. XPS, FTIR, and zeta potential techniques confirmed the presence of these ligands on GNPs. The results indicated that functionalized ligands could be utilized to control the size and functionalize the GNP surface. Hence our approach could simultaneously achieve two goals: precise size-control and functionalization of GNPs without the ligand-exchange step.

The kinetic energy of PAH dication and trication dissociation determined by recoil-frame covariance map imaging

We investigated the dissociation of dications and trications of three polycyclic aromatic hydrocarbons (PAHs), fluorene, phenanthrene, and pyrene. PAHs are a family of molecules ubiquitous in space and involved in much of the chemistry of the interstellar medium. In our experiments, ions are formed by interaction with 30.3 nm extreme ultraviolet (XUV) photons, and their velocity map images are recorded using a PImMS2 multi-mass imaging sensor. Application of recoil-frame covariance analysis allows the total kinetic energy release (TKER) associated with multiple fragmentation channels to be determined to high precision, ranging 1.94-2.60 eV and 2.95-5.29 eV for the dications and trications, respectively. Experimental measurements are supported by Born-Oppenheimer molecular dynamics (BOMD) simulations.

Disentangling sequential and concerted fragmentations of molecular polycations with covariant native frame analysis

We present results from an experimental ion imaging study into the fragmentation dynamics of 1-iodopropane and 2-iodopropane following interaction with extreme ultraviolet intense femtosecond laser pulses with a photon energy of 95 eV. Using covariance imaging analysis, a range of observed fragmentation pathways of the resulting polycations can be isolated and interrogated in detail at relatively high ion count rates (∼12 ions shot^-1). By incorporating the recently developed native frames analysis approach into the three-dimensional covariance imaging procedure, contributions from three-body concerted and sequential fragmentation mechanisms can be isolated. The angular distribution of the fragment ions is much more complex than in previously reported studies for triatomic polycations, and differs substantially between the two isomeric species. With support of simple simulations of the dissociation channels of interest, detailed physical insights into the fragmentation dynamics are obtained, including how the initial dissociation step in a sequential mechanism influences rovibrational dynamics in the metastable intermediate ion and how signatures of this nuclear motion manifest in the measured signals.

BIAN-Aluminium-Catalysed Imine Hydrogenation

Hydrogenations have been dominated by transition metal catalysis, while the use of more abundant and inexpensive main group metal catalysts has remained a great challenge. Here, a bimetallic Li/Al dihydride was successfully applied to catalytic hydrogenations of imines. The catalyst [(DippBIAN)Al(μ-H)2Li(OEt2)2] was easily prepared from the 2e-reduced BIAN derivative and LiAlH4.

Exploration and validation of force field design protocols through QM-to-MM mapping

The scale of the parameter optimisation problem in traditional molecular mechanics force field construction means that design of a new force field is a long process, and sub-optimal choices made in the early stages can persist for many generations. We hypothesise that careful use of quantum mechanics to inform molecular mechanics parameter derivation (QM-to-MM mapping) should be used to significantly reduce the number of parameters that require fitting to experiment and increase the pace of force field development. Here, we design and train a collection of 15 new protocols for small, organic molecule force field derivation, and test their accuracy against experimental liquid properties. Our best performing model has only seven fitting parameters, yet achieves mean unsigned errors of just 0.031 g cm^-3 and 0.69 kcal mol^-1 in liquid densities and heats of vaporisation, compared to experiment. The software required to derive the designed force fields is freely available at https://github.com/qubekit/QUBEKit.

Selective carbon-phosphorus bond cleavage: expanding the toolbox for accessing bulky divalent lanthanoid sandwich complexes

The synthesis of two new tetra- and penta-phenycyclopentadienyldiphenylphosphine pro-ligands which readily undergo selective C-P bond cleavage has allowed for the facile synthesis of bulky divalent octa- and deca-phenylmetallocenes of europium, ytterbium and samarium.

Recent advances in the aqueous applications of PEDOT

Water is ubiquitous in life - from making up the majority of the Earth's surface (by area) to over half of the human body (by weight). It stands to reason that materials are likely to contact water at some point during their lifetime. In the specific case of sensors however, there is a need to consider materials that display stable function while immersed in aqueous applications. This mini-review will discuss the most recent advances (2018 to 2021) in the application of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) in aqueous environments. At its heart, the use of PEDOT in aqueous applications relies on nanoscale understanding and/or nanoengineered structures and properties. This enables their use in water-based settings such as within the human body or buried in agricultural soils.

X-ray absorption spectra of f-element complexes: insight from relativistic multiconfigurational wavefunction theory

X-ray absorption near edge structure (XANES) spectroscopy, coupled with ab initio calculations, has emerged as the state-of-the-art tool for elucidating the metal-ligand bonding in f-element complexes. This highlight presents recent efforts in calculating XANES spectra of lanthanide and actinide compounds with relativistic multiconfiguration wavefunction approaches that account for differences in donation bonding in the ground state (GS) versus a core-excited state (ES), multiplet effects, and spin-orbit-coupling. With the GS and ES wavefunctions available, including spin-orbit effects, an arsenal of chemical bonding tools that are popular among chemists can be applied to rationalize the observed intensities in terms of covalent bonding.

Redox-active BIAN-based Diimine Ligands in Metal-Catalyzed Small Molecule Syntheses

α-Diimine ligands have significantly shaped the coordination chemistry of most transition metal complexes. Among them, bis(imino)acenaphthene ligands (BIANs) have recently been matured to great versatility and applicability to catalytic reactions. Besides variations of the ligand periphery, the great versatility of BIAN ligands resides within their ability to undergo facile electronic manipulations. This review highlights key aspects of BIAN ligands in metal complexes and summarizes recent contributions of metal-BIAN catalysts to syntheses of small and functionalized organic molecules.

An overview of chemo- and site-selectivity aspects in the chemical conjugation of proteins

The bioconjugation of proteins-that is, the creation of a covalent link between a protein and any other molecule-has been studied for decades, partly because of the numerous applications of protein conjugates, but also due to the technical challenge it represents. Indeed, proteins possess inner physico-chemical properties-they are sensitive and polynucleophilic macromolecules-that make them complex substrates in conjugation reactions. This complexity arises from the mild conditions imposed by their sensitivity but also from selectivity issues, viz the precise control of the conjugation site on the protein. After decades of research, strategies and reagents have been developed to address two aspects of this selectivity: chemoselectivity-harnessing the reacting chemical functionality-and site-selectivity-controlling the reacting amino acid residue-most notably thanks to the participation of synthetic chemistry in this effort. This review offers an overview of these chemical bioconjugation strategies, insisting on those employing native proteins as substrates, and shows that the field is active and exciting, especially for synthetic chemists seeking new challenges.

Site-selective and inducible acylation of thrombin using aptamer-catalyst conjugates

Two acyl-transfer catalysts were conjugated to thrombin-binding DNA aptamers to acylate thrombin. Modification occurred site-selectively on Lys (≫Ser) residues proximal to the respective aptamer-thrombin interface, was selective for thrombin in the presence of other proteins, and the activity of both DNA-catalysts could be controlled by an external trigger.

Amphiphilic Fullerene-BODIPY Photosensitizers for Targeted Photodynamic Therapy

Nanotheranostic tailor-made carriers are potent platforms for the treatment of cancer that propound a number of advantages over conventional agents for photodynamic therapy (PDT). Herein, four new heavy atom free amphiphilic glucose-BODIPY-fullerene dyads (14-17) endowed with carbohydrate units in the styryl units, which can also form nanomicelles (14-17NM) with Tween 80 for PDT are reported. Glucose-BODIPY-fullerene systems (14-17) and related nanomicelles (14-17NM) have been prepared to emcee efficient singlet oxygen generation upon light irradiation. In vitro anti-tumor effects of the compounds 14-17 and 14-17NM in the presence of light and in darkness have been investigated with K562 human chronic myelogenous leukemia suspension cells. Anti-tumor toxicity upon light irradiation was due to the formation of singlet oxygen and reactive oxygen species (ROS). This study may provide an accomplished example of efficient PDT applications based on nanovehicles fabricated with universal spin converter, fullerene, light harvesting unit, BODIPY dyes conjugated with targeting units to fight against cancer.